Rébecca Deneckère
email: denecker@univ-paris1.fr

Adrian Iacovelli
email: adrian.iacovelli@univ-paris1.fr

Elena Kornyshova
email: kornyshova@univ-paris1.fr

Carine Souveyet
email: souveyet@univ-paris1.fr

From Method Fragments to Method Services

Keywords: Method Engineering, Method Fragment, Method Service

In Method Engineering (ME) science, the key issue is the consideration of information system development methods as fragments. Numerous ME approaches have produced several definitions of method parts. Different in nature, these fragments have nevertheless some common disadvantages: lack of implementation tools, insufficient standardization effort, and so on. On the whole, the observed drawbacks are related to the shortage of usage orientation. We have proceeded to an in-depth analysis of existing method fragments within a comparison framework in order to identify their drawbacks. We suggest overcoming them by an improvement of the "method service" concept. In this paper, the method service is defined through the service paradigm applied to a specific method fragment -chunk. A discussion on the possibility to develop a unique representation of method fragment completes our contribution.

Introduction

Method engineering (ME) science deals with information systems (IS) development methods. One of the ME fundamentals for optimizing, reusing, and ensuring flexibility and adaptability of these methods is their decomposition into modular parts [START_REF] Rolland | L'ingénierie des méthodes : une visite guidée[END_REF].

There are various representations of building blocks. This purpose is discussed in the literature [START_REF] Agerfalk | Modularization Constructs in Method Engineering: Towards Common Ground?[END_REF][START_REF] Henderson-Sellers | Situational Method Engineering: Fragments or Chunks?[END_REF][START_REF] Aharoni | Representation of method Fragments, a comparative study[END_REF] and gives an overview of five different building blocks: fragments [START_REF] Brinkkemper | Method Engineering: engineering of information systems development method and tools[END_REF], chunks [START_REF] Rolland | Specifying the reuse context of scenario method chunks[END_REF], components [START_REF] Wistrand | Method components: Rationale revealed[END_REF], OPF fragments [START_REF] Henderson-Sellers | Process meta-modelling and process construction: examples using the OPF[END_REF], and method services [START_REF] Guzélian | SO2M : Towards a Service-Oriented Approach for Method Engineering[END_REF]. We will use the term "Fragment" in this work as a generic term for all kinds of building blocks. Historically, the term fragment was the first one to appear, long before component, chunk, and so on. Brinkkemper defines a method fragment as "a coherent piece of an IS development method" [START_REF] Brinkkemper | Method Engineering: engineering of information systems development method and tools[END_REF]. Therefore, we consider this definition as the simpler one and that all others are essentially its extensions, which is the reason why we have chosen this term. The description of fragments is strongly linked to the approaches that suggest them. For this reason, we consider the fragment definitions as joint notions of ME approaches.

Despite their diversity, different method fragments have some common drawbacks. To identify them, we elaborate a comparison framework. From the application of our comparison framework on the five selected fragments, we deduce that a sufficient tool support is not provided for them and for their use (interactivity with users). Moreover, the interoperability of the proposed proprietary solutions is not handled. In addition, the complexity of data exchanged is not completely addressed.

In order to overcome these drawbacks, we suggest improving Rolland's proposal [START_REF] Rolland | Method Engineering : Achievements,Trends & Challenges[END_REF] about applying the service-based approach to ME needs. This concerns the adaptation of Service Oriented Architecture (SOA) [START_REF]W3C: Web Services Architecture (WSA)[END_REF] to method fragment by developing a Method Oriented Architecture (MOA). In this manner, we improve the concept of "method service".

Our method service contains two parts: descriptor and implementation parts. The descriptor part combines a semantic descriptor (based on the fragment definition of the method chunks approach) and an operational descriptor describing the implementation part that operates the process of the fragment. Technical issues of method services are addressed with the application of widely used standards of service-based approaches.

Thus, this study joins the ME field with the proposal of a framework used for comparing different representations of method building blocks, for identifying their drawbacks, and suggesting a solution to solve them.

This paper is organised as follows. Our comparison framework is described in the next section and it is applied on three selected method fragments in the third section. Following the concluding remarks of this comparison, the concept of the method service is developed in section 4. A discussion about a unique concept of method fragments is addressed in section 5 and section 6 concludes this work with our contribution and research perspectives.

Comparison Framework

We have elaborated a framework to compare different method fragments. The idea to consider a central concept (here the method fragment) on four different points of view is largely inspired from [START_REF] Rolland | A Proposal for a Scenario Classification Framework[END_REF], a work dealing with evolution scenarios. To elaborate our comparison framework, we have proceeded to an analysis of issues that are crucial for a "good" IS development method and, at the same time, not-solved by existing method Fragments. As a result, our framework contains 15 attributes organized into 4 views (cf. Fig. 1) developed in the following subsections.

Objective View

This view captures why we should use a specific method fragment and what are the benefits retrieved from its practical application.

A point to consider is the fragment interoperability with other fragments. The interoperability has been discussed since the beginning of ME science [START_REF] Brinkkemper | Method Engineering: engineering of information systems development method and tools[END_REF]. However, the majority of fragments are conceived to be interoperable only with the fragments stored in the same method base ("internal" interoperability). In the real world project, the situation is widespread when the interoperability is required with other elements (external to method base) on the same or on different development platforms (external interoperability within or not the same environment).

Staying within the fragments' environment, benefits are retrieved from the degree of interactions with the method engineer. This interactivity is decomposed into three possible levels. ME approaches should either provide a fully automated or assisted (semi-automated) process for construction, reuse and composition of fragments. At least, the ME approach application can be manual.

Usage View

This view deals with different aspects that describe the fragment usage.

Seligmann gives a definition of a method as "a way of thinking, a way of modelling, a way of working and a way of supporting" [START_REF] Seligmann | Analysing the structure of IS methodologies, an alternative approach[END_REF]. However, even if a lot of fragments are considered as complete method, often they are not adapted to satisfy all these requirements. We investigate this question through the covered way.

The methods fragments application needs to be supported by a tool. [START_REF] Brinkkemper | Method Engineering: engineering of information systems development method and tools[END_REF] defines a tool as "possibly automated means to support a parts of development process". We distinguish different ways of fragment implementation: first, the implementation of process and product parts of the method fragment and, second, the implementation of fragments' storage, retrieval, and construction. Even if all ME approaches investigate storing methods fragments in the "method base" or "method repository" [START_REF] Brinkkemper | Method Engineering: engineering of information systems development method and tools[END_REF][START_REF] Rolland | Specifying the reuse context of scenario method chunks[END_REF][START_REF] Gonzales-Perez | Supporting Situational Method Engineering with ISO/IEC 24744 and the Work Product Tool Approach[END_REF], this information is relevant as all the other implementation parts are founded on this one. Hence, our tool/implementation attribute takes the following values: product storage and manipulation, process operating, retrieval, and construction.

Subject View

This view answers the « What » question. This means that we will develop facets concerning the internal structure and formalisation of the fragment.

An observation of the literature guided us to define three possible levels in which we may consider fragments: intentional, structural, operational levels. The intentional level allows defining the context of use and/or reuse of fragments. The structural level determines the fragment structure and the kind of structural links between the fragment elements: specialization, composition and references. The operational level deals with operating part of fragment (allowing its implementation during development project).

The method fragment could be also characterized with relation to its main elements. Depending on the dominant element, [START_REF] Henderson-Sellers | SPI -A role for Method Engineering[END_REF] identifies three key perspectives for fragments description: process focussed, product focussed, and producer focussed.

Another important aspect of the fragment is the recursion. The concept of granularity is used in several approaches to allows the possibility to compose a fragment with others fragments. For instance, a fragment may be an entire method that can be decomposed in other less complex fragments (which, in turn, may also be decomposed in other more simple fragments).

A fragment may also be defined at different abstraction levels. We consider the following levels: meta-meta-model, meta-model, model [16]. [START_REF] Brinkkemper | A method engineering Language for the description of systems development methods[END_REF] explores the notion of the fragment formalism that can be either conceptual when fragments are expressed with descriptions and specifications of methodology parts, or technical when there is an implementation of operational parts with tools.

Process View

The process view considers different ways of method fragments conception and usage. The attributes of this view aim at describing the main ME activities dealing with fragments (method decomposition, fragment selection, new method construction, and so on).

First, the methods are decomposed into methods fragments which are stored in method base (or repository). Thus, we define the facet "decomposition principle" which deals with different ways to decompose methods into fragments. This principle predefines the fragments description used for their identification during project fulfilment.

Once the methods are decomposed and stored in the base, they could be used in the projects. On the first step, the engineer must find in the method base the fragments that better match the project specificities. On this basis, we identify two facets: retrieval/selection principle and matching with situation. The retrieval/selection principle defines steps to carry out for identifying an appropriate fragment. In ME, all approaches are situational, which means they take into account the specific project situation by different manners. This aspect is considered within the matching with situation attribute.

The next step is to build a new method from the selected fragments. Based on [START_REF] Nehan | Component-based Situational Methods: A framework for understanding SME[END_REF], we distinguish the following main manners to use fragments for constructing a new method according to project specificities: assembly, extension, and reduction. By assembly, separate fragments are grouped with regard to the studied specific project to form a unique method [START_REF] Ralyté | Towards a Generic Model for Situational Method Engineering[END_REF]. By applying extension, a basic method is transformed into a new one by addition of new fragments [START_REF] Ralyté | Towards a Generic Model for Situational Method Engineering[END_REF]. By reduction, some fragments are removed from the basic method in order to transform it to match the engineer's needs [START_REF] Wistrand | Method components: Rationale revealed[END_REF]. In the real world projects, with time and resource constraints, where is a need for constructing methods dynamically depending on the project specificity and adapting it during its realization if project characteristics change. This property implies the agility of methods. Recently, the agility was discussed with regards to methods of IS development [START_REF] Abrahamsson | Agile Software Development Methods: Review and Analysis[END_REF]. However, agility in ME approaches is not widely spread and is only suggested in recent works. To consider this kind of construction, we introduce the fourth value for the given attribute "agile construction" having a Boolean value.

Framework Application

Several types of fragments have emerged in the literature. The most known of these different kind of representation are method fragments, method chunks, component, OPF fragment, and method services [START_REF] Agerfalk | Modularization Constructs in Method Engineering: Towards Common Ground?[END_REF]. Before applying our comparison framework to these fragments (sub-section 3.2), we give their brief overview in the following sub-section.

Overview of Existing Method Fragments

In order to succeed in creating good methodologies that best suit given situations, fragments representation and cataloguing are very important activities. In particular, they have to be represented in a uniform way that includes all the necessary information that may influence their retrieval, integration or assembling. The five above-mentioned method fragments are presented in the Figure 2. and quickly described below.

Method fragments (cf. Figure 2.A) [START_REF] Brinkkemper | Method Engineering: engineering of information systems development method and tools[END_REF][START_REF] Harmsen | Situational Method Engineering for information Systems Project Approaches Int[END_REF] are standardised building blocks based on a coherent part of method. A fragment is either a Product or a Process fragment and is stored on a method base from which they can be retrieved to construct a new method following assembly rules [START_REF] Brinkkemper | A method engineering Language for the description of systems development methods[END_REF].

The latest description of a method chunk [START_REF] Agerfalk | Modularization Constructs in Method Engineering: Towards Common Ground?[END_REF] describes it as a way to capture more of the situational aspects in ME and to appropriately support the retrieval process. A chunk [START_REF] Rolland | Specifying the reuse context of scenario method chunks[END_REF] based method aims at associating the reusable components to their description in order to facilitate component research and extraction according to the user's needs (cf. Figure 2

.B).

For [START_REF] Agerfalk | Modularization Constructs in Method Engineering: Towards Common Ground?[END_REF], method components developed in [START_REF] Wistrand | Method components: Rationale revealed[END_REF][START_REF] Agerfalk | Information systems actability: Understanding Information Techology as a Tool for Business Action and Communication[END_REF][START_REF] Karlsson | Method Configuration: Method and Computerized Tool Support[END_REF] allow to view methods as constituted by exchangeable and reusable components. Each component consists of descriptions for process (rules and recommendations), notations (semantic, syntactic and symbolic rules for documentation), and concepts (cf. Figure 2.C). [START_REF] Karlsson | Method Configuration: Method and Computerized Tool Support[END_REF] introduces the notion of method rationale which is the systematic treatment of the arguments and reasons behind a particular method [START_REF] Agerfalk | Information systems actability: Understanding Information Techology as a Tool for Business Action and Communication[END_REF].

In the OPEN Process Framework (OPF) [START_REF] Henderson-Sellers | Process meta-modelling and process construction: examples using the OPF[END_REF], the fragment is generated from an element in a prescribed underpinning meta-model [START_REF] Agerfalk | Modularization Constructs in Method Engineering: Towards Common Ground?[END_REF]. This meta-model (cf. Figure 2.D) has been upgraded with the availability of the international standard ISO/IEC 24744 [START_REF]Metamodel for development Methodologies[END_REF]. SO2M (Service Oriented Meta-Method) [START_REF] Guzélian | SO2M : Towards a Service-Oriented Approach for Method Engineering[END_REF] develops a new kind of fragment called offers a repository with a large variety of method fragments, called method services together with, and a service composition process. During composition, the process guides developer's choices; it selects method services and delivers a method fragment that achieves a developer's requirement. The SO2M meta-model is based on three main principles: service orientation, task ontology for reuse of knowledge on development problems and dynamic construction of method services for generating tailored methods (cf.

Comparative Analysis within Framework

The table (cf. Appendix) presents a comparative analysis of the five selected fragments. This table is explained in this sub-section, attribute by attribute. Interoperability. All fragments provide an internal interoperability, i.e. with fragments in the same method base. OPF fragments [START_REF] Gonzales-Perez | Supporting Situational Method Engineering with ISO/IEC 24744 and the Work Product Tool Approach[END_REF] can deal with an external interoperability in the same environment by using the object serialisation. Due to this serialisation, it can not be applied on different platforms. Method services [START_REF] Guzélian | SO2M : Towards a Service-Oriented Approach for Method Engineering[END_REF] grant a fully external interoperability with a decentralised interoperable service oriented approach.

Interactivity with user. In most ME approaches, the creation, retrieval, composition, and application of fragments is done manually. Some efforts have been done with method fragments and method services to provide tools to assist the different users. However, most of their aspects are still done manually.

Covered way. All fragments help to construct methods that partly cover Seligmann definition of a method [START_REF] Seligmann | Analysing the structure of IS methodologies, an alternative approach[END_REF]. Indeed, each constructed method answers to a particular paradigm ('way of thinking') and has two different parts, namely the "product" ('way of modelling') and the "process" ('way of working'). However, not a single one of them is able to meet all the tool requirements ('way of supporting').

Tools/implementation. All considered ME approaches provide a tool for storing method fragments in a database. Method chunks also allow a more efficient retrieval of stored knowledge with the Method Chunk Repository [START_REF] Jeusfeld | Classifying Interoperability Problems for a Method Chunk Repository[END_REF]. Two other approaches go further in tool supporting. In addition to the fragments selection and retrieving, the first one (method fragments with a tool called Decamerone) contains the product part elements [START_REF] Brinkkemper | Method Engineering: engineering of information systems development method and tools[END_REF] and the second one (method services of SO2M approach) uses resource descriptions and execution graphs for implementing resource part [START_REF] Guzélian | SO2M : Towards a Service-Oriented Approach for Method Engineering[END_REF]. However, the method service is viewed as a "black box" without any explanation on how it is developed. The OPF fragment authors develop an implemented product part within an "Eclipse" tool [START_REF] Firesmith | Method Engineering Using OPFRO[END_REF].

Level. The intentional level is present in all fragments excepted the method fragment one. The chunk's intentional level contains an interface (situational and intentional aspects) and a descriptor (set of criteria to locate the best engineering situation) [START_REF] Mirbel | Situational method engineering : combining assembly-based and roadmap-driven approaches[END_REF]. For method component, the intentional level includes goal's identification. The OPF fragment is selected by its goal. The method service's identification part defines the purpose of the service: the finality (the problem that the method service solves) and the argument (advantages and drawbacks of using the method service). All fragments have a structural level. The operational part at the level of meta-model is included only in method service.

Perspective. The method fragments are defined as either process part or product part [START_REF] Brinkkemper | Method Engineering: engineering of information systems development method and tools[END_REF][START_REF] Brinkkemper | A method engineering Language for the description of systems development methods[END_REF], whereas all the other fragments include both the interrelated parts in their definition. The third perspective (producer) is addressed in only two blocks: component and OPF fragment [START_REF] Agerfalk | Modularization Constructs in Method Engineering: Towards Common Ground?[END_REF]. In [START_REF] Brinkkemper | Method Engineering: engineering of information systems development method and tools[END_REF], roles of people are included as a property of the method fragment.

Recursion. Even if nearly all ME approaches insist on the different layers of fragment granularity (a fragment may be either a method part or a complete method [START_REF] Brinkkemper | Method Engineering: engineering of information systems development method and tools[END_REF][START_REF] Brinkkemper | A method engineering Language for the description of systems development methods[END_REF]), only the method chunks can be described as completely recursive. A chunk is based on the decomposition of the method process model into reusable guidelines [START_REF] Ralyte | An Approach for Method Reengineering[END_REF], which means that all chunks may be formally decomposed in other complete chunks. The other types of fragments are not formally defined to deal with process decomposition.

Abstraction level. All fragments are defined at the level of meta-models (cf. Figure 1.). The method service includes a meta meta model level because this approach suggests a ontology used for describing product model [START_REF] Guzélian | SO2M : Towards a Service-Oriented Approach for Method Engineering[END_REF]. The OPF fragment contains also an endeavour, which is an instance of model and corresponds to a schema of development method [START_REF] Gonzales-Perez | Supporting Situational Method Engineering with ISO/IEC 24744 and the Work Product Tool Approach[END_REF].

Formalism. Chunks and components use conceptual formalisms, when the OPF fragments and method services support technical presentation. The method fragment contains both conceptual and technical representations [START_REF] Brinkkemper | A method engineering Language for the description of systems development methods[END_REF].

Decomposition Principle. The decomposition principle is quite different following the fragment type. Method fragment uses a tree decomposition to link all coherent method parts. Chunks are obtained by intentional decomposition of methods [START_REF] Ralyté | Towards a Generic Model for Situational Method Engineering[END_REF]. The OPF fragment is a "clabject", which is a result of both instantiation and inheritance [START_REF] Gonzales-Perez | Supporting Situational Method Engineering with ISO/IEC 24744 and the Work Product Tool Approach[END_REF]. Components are decomposed by goals [START_REF] Wistrand | Method components: Rationale revealed[END_REF]. The method service approach does not specify this attribute value.

Retrieval/Selection Principle. The retrieval and selection of a method fragment are made by different types of queries. Chunks are selected with the application of similarity measures of their descriptors and interfaces. This helps to evaluate the degree of matching between them and the requirements [START_REF] Ralyté | Towards a Generic Model for Situational Method Engineering[END_REF]. On the same way, the method service selection is made by a comparison of the requirements (expressed by intentions) with the service intentional descriptors by ontologies, which allow comparing the semantic similarity [START_REF] Guzélian | SO2M : Towards a Service-Oriented Approach for Method Engineering[END_REF]. Differently, OPF fragments, stored on a 'work product tool', are selected with queries on their endeavour [START_REF] Gonzales-Perez | Supporting Situational Method Engineering with ISO/IEC 24744 and the Work Product Tool Approach[END_REF]. Method fragments are selected by application of request on the goal [START_REF] Harmsen | Situational Method Engineering for information Systems Project Approaches Int[END_REF].

Matching with situation. Approaches don't match the situation with the same techniques. The method fragment definition consists in encouraging a global analysis of the project while basing itself on contingency criteria. Projects and situations are characterized by means of factors associated with the methods. The chunk approach includes projects requirements expressed as a requirements map [START_REF] Ralyté | Towards a Generic Model for Situational Method Engineering[END_REF], which is used to test the similarity between requirements and existing fragments. In component containing its "rational", the matching is performed by goal analysis [START_REF] Wistrand | Method components: Rationale revealed[END_REF]. The Method service approach uses an identification part that defines the purpose of the service. The matching is thus done by using goal, actor, process, and product ontologies [START_REF] Guzélian | SO2M : Towards a Service-Oriented Approach for Method Engineering[END_REF].

Construction technique. The method fragments are assembled for creating a new method. The chunk approach uses assembly (allowing overlapping between different chunks) and extension. In addition to the assembling and extending, the component approach suggests method reduction. The method service construction is based on a composition process that supports the aggregation of services in sequence or in parallel [START_REF] Guzélian | SO2M : Towards a Service-Oriented Approach for Method Engineering[END_REF]. In the OPF approach, a new method is constructed by dynamic instantiation of fragments during the project. Hence, the OPF approach suggests an agile construction of methods.

Drawbacks of Existing Method Fragments

The framework analysis allows identifying the following main drawbacks of existing method fragments. (i) The way of supporting method fragments is not sufficiently managed by ME approaches to produce new method with tool support. (ii) The ME approaches themselves are not enough automated. They limit their tool support to a description language, a method fragment repository, and retrieval facilities. (iii) Moreover, the handle of abstraction levels in fragments is not complete in all ME approaches. Fragments work at different abstraction level and the whole complexity of exchanged data is not addressed and causes a restriction of exchanges between them. (iv) Despite standardisation efforts of the ME community, there is no unified description language of a method fragment and interoperability issues between the various fragments method databases are not handled.

Our proposal to solve these problems is to carry on the approach proposed by C. Rolland in [START_REF] Rolland | Method Engineering : Achievements,Trends & Challenges[END_REF], i.e. to consider the method fragment as a service.

Proposed Solution

To develop the concept of method service, we use the Service Oriented Architecture (SOA) [START_REF]W3C: Web Services Architecture (WSA)[END_REF] and the method chunk definition.

Indeed, the SOA applied to ME needs may solve the limitation of existing ME approaches. The adaptation of the SOA to the ME -the Method Oriented Architecture (MOA) -defines a method services registry where a list of available method services is organised. This provides access to decentralised method service providers for ME engineers and developers and interoperable method services.

Moreover, according to the MOA, each method service has to be considered as a standalone component, which should be retrieved and selected dynamically. Each granularity of method service can be then viewed and executed as a method. To be compliant to this requirement, we based our method services on the method chunk for two reasons : (i) the intentionality (decomposition and retrieving). We decompose the methods into method services according to an intentional principle. We use the descriptor and interface of the method chunk in order to describe our method services intentional part. This part will be used for retrieving and selecting method services from the registry (ii) the recursion. Chunks use an intentional decomposition, which means that they are using the composition principle with a description of their intention (objective the engineer will reach if he uses it). To decompose a main intention into simpler ones allows a decomposition of a method into chunks logically related to each other and always described on the same way. This recursive description of the chunks will allow us to implement our services according to the MOA principles of process composition.

Satisfying the MOA requirements, our implementation of method services has to deal with the identified drawbacks by applying our comparison framework. To overcome them, a method service has to deal with four keys technical issues [START_REF] Souveyet | Method as a Service (MaaS)[END_REF]: complexity, interoperability, composition, and interactivity. These issues can be addressed by the application of standards used in service-oriented approaches. Table 1. shows, for each issue, the suggested standards and their usage objectives.

The usage orientation is emphasised by this solution in several directions:  Adoption of an open and distributed architecture to design, to distribute, and to execute method chunks.

 Enrichment of the semantic descriptor of method chunks with their corresponding software module, called method service.

 Adoption of standards widely used coming from web services technologies to implement method services.

Issue

Standard Objective exchanged data complexity XMI -XML Metadata Interchange [START_REF]Object Management Group (OMG): XML Metadata Interchange (XMI) v2.1[END_REF] external data exchange on all levels MOF -Meta Object Facility [16] modeling levels handling interoperability SOAP -Simple Object Access Protocol [START_REF] Gudgin | SOAP V.1.2[END_REF] method services communication WSDL -Web Services Description Language [START_REF] Christensen | Web Services Description Language (WSDL) 1.1[END_REF] method services descriptions UDDI -Universal Description Discovery and Integration [33] service registry XMI standardisation of exchanged products MOF standardisation of exchanged products composition BPEL -Business Process Execution Language [START_REF]OASIS: Web Services Business Process Execution Language Version 2[END_REF] method services operational parts composition interactive web services WSRP -Web Services for Remote Portlets [START_REF]OASIS: Web Services for Remote Portlets Specification 1[END_REF] method services user interface handling

Method Service Structure

The method service structure combines a descriptor part with its implementation part as shown on Figure 3. The descriptor part aims at documenting, retrieving, composing, and invoking the related implementation part. The tool support is realised by the implementation part of a method service. Each granularity level of method service is executable and may be a composition of method services. The semantic descriptor describes the chunk implemented by the method service. The main purpose of this descriptor is to document method services through four subparts: Intention, Paradigm, Process and Product. In the method chunk approach, the retrieval and composition of fragments are done by intentions. We propose to carry on this principle to base the retrieving and the composition of method services on the four sub-parts of the semantic descriptor.

The intention defines the intentions of the method service use and the context in which it can be reused. The paradigm describes the fragment's way of thinking. The process is the description of activities executed on input products. The product is the meta-model description of input and output product models of the method service.

The operationalisation of method services is performed by an operational descriptor and an implementation part. It implements the process described in the semantic part by a web service or a composition of web services (BPEL process) exposed by a WSDL descriptor. The implemented web service is a tool providing the way of supporting method services. The product dimension is implemented by metamodels compliant to Meta Object Facility (MOF) standard and XMI schema standard.

The WSDL is the operational descriptor of a method service. It contains the definitions of each performed operation including their inputs, and outputs messages (XMI product message).

Method Oriented Architecture

As indicated above, the MOA (proposed in [START_REF] Rolland | Method Engineering : Achievements,Trends & Challenges[END_REF]) is an adaptation of the SOA to ME. Figure 4 shows the three actors and their interactions in the MOA: the method provider, the method registry, and the method client. The method provider creates method services and publishes their descriptors on the method registry. The method client retrieves method services from the registry, using retrieval facilities built upon semantic descriptors. Operational descriptors (WDSL) are used by method clients to invoke the implementation part of method services from their provider. This implementation of the fragment process is either an atomic web service or a composition of web services realised by a BPEL process.

The MOA usage can be sketched according to two use cases:  developers using CASE tools to invoke remote method services.  method engineers using CAME tools to define new methods with method services composition facilities.

This MOA provides an open and decentralised access to method services for method client tools built on a Software as a Service (SaaS) architecture [START_REF] Papazoglou | Service-Oriented Computing: Concepts, Characteristics and Directions[END_REF].

Method Service Characterization according to the Framework

A method service reuses the method chunks characteristics. Indeed, its semantic descriptor is inspired by method chunk descriptor. However, it includes also the way of supporting by its operational descriptor and its implementation part. We have defined our method service based on the comparison framework:

Objective view {Interoperability = "external in different environments"; Interactivity with user = "automated"} Usage view {Covered ways = "thinking, modeling, working, supporting"; Tools / implementation = "storage, manipulation, operating, retrieval, construction"} Subject view {Level = "intentional, structural, operational"; Perspective = "Process focussed, Product focussed"; Recursion = yes; Abstraction level = "meta-meta-model, meta-model, model, schema"; Formalism = "conceptual, technical"} Process view {Decomposition principle = "by intentions"; Retrieval/selection principle = "request by paradigms, intentions, processes, products"; Matching with situation = "not specified"; Construction technique = "agile"}

We may observe with this definition that we have tried to overcome the drawbacks identified in the section 3.3. First of all, this fragment is a "real" method fragment as it covers the four parts of Seligmann definition [START_REF] Seligmann | Analysing the structure of IS methodologies, an alternative approach[END_REF] by developing the full support of the method service. The interoperability issue is ensured by the adoption of widely used standards, coming from the web service and from the meta data exchange technologies. Creation, retrieval, composition, and application of method fragments are automated in our MOA based approach. The intentional decomposition principle gives a recursive view and the fragment is viewed as a service. Finally, our suggestion allows an agile construction of situational methods.

Basic Application of the Method Service approach

The following figures illustrate our approach with the description and application of a method service called Objectify (Fig 5 and Fig. 6). This service implements the process of making out an object out of a relationship (known as objectification, reification, or nesting) [START_REF] Halpin | Objectification[END_REF].

Fig. 5 shows the semantic descriptor of this method service. The product part shows the input and the output class diagram parts whereas the process part shows the operations which has to be executed on the input product to reach the method service intention and obtain the output product. Fig. 6 shows a part of the method service implementation. We focus on the invocation of the web service implementation. There is other processes that have to be taken into account to implement this approach, as the search and retrieval of the descriptor (WSDL), but we thought that this one will be enough here to give a relevant example to illustrate this work. As mentioned above, in table 1, we choose to use XMI standard for data exchange. Consequently, the input class diagram needs to be represented using XMI to produce a XMIDocument (step 1) which will be understandable by a method service. This one is the implementation of a method service process part and has to be applied on the XMIDocument. At this point, several implementation solutions are possible. For instance, the method service directly modify the XML code of the XMIDocument, either by an algorithm application, a modification of the DOM (Document Object Model) tree [START_REF]W3C: Document Object Model[END_REF] or by an XSLT transformation [START_REF]W3C: XSL Transformations[END_REF], or it may be instantiated to manipulate objects. In our illustration, we choose this last solution because it induces a more easy transformation (step 2) and instantiate the XMIDocument according to the UML Meta Model (MOF compliant) [40]. Then, we manipulate the created objects by a simple algorithm in order to perform the chunk process part (step 3). Once modified, the instance of the input XMIDocument is used to generate the output XMIDocument (step 4) which represents the transformed class diagram (step 5).

Discussion: Toward a Unique Concept of Fragment

Different method fragments and their correlations represent a main purpose of ME science. An attempt to find a unique concept was made during the panel of the ME conference [START_REF] Agerfalk | Modularization Constructs in Method Engineering: Towards Common Ground?[END_REF]. In this section, we present our point of on this problem and discuss the possibility to lead to a unique vision of fragment with regard to the suggested definition of method service. The creation of a unique concept will be confronted to several challenges to solve. The definition of a method by [START_REF] Seligmann | Analysing the structure of IS methodologies, an alternative approach[END_REF] decomposes a method in four ways, which have to be addressed by the unique concept of fragment. Furthermore, in a general way this unique fragment will have to cover all the concepts contained in actual fragments. Afterwards, in a practical view, the four technical issues enounced in section 4.1 (complexity, interoperability, composition, and interactive web services) have to be considered. Some advantages could be retrieved from a unique concept like the standardisation of method fragments providing an interoperability of solutions, encouraging the share and use of fragments.

Nevertheless, covering all aspects of method fragments in a unique fragment is a difficult task. Therefore, we propose to define some essential aspects required for a unique fragment representation. For the fragment purpose, five aspects have to be considered: intentionality, reusability, interoperability, interactivity, and implementation.

Our proposal of the method service improvement addresses most challenges of a unique fragment concept. The four ways of a method and technical issues are considered, but the covering all existing method fragments aspects is not provided. Therefore, intentionality and reusability objectives are not yet completely implemented. The implementation of our semantic descriptor and its associate platform will solve these two problems.

Conclusion

In this paper, our contribution is double: we define a comparison framework in order to identify the drawbacks of existing method fragments and propose an improvement of the method service concept to solve them.

The suggested framework allows a comparison structured in four views and the following purposes: (i) to have an overview of existing method fragments, (ii) to define drawbacks of existing method fragments, and (iii) to analyse the possibility to converge on a unique fragment concept.

Based on this framework analysis, we propose to improve the method service concept in order to:

 overcome the following drawbacks of existing method fragments with the application of service-oriented approaches standards: insufficient consideration of complexity, lacks of interoperability, and lacks of interactivity;

 encourage the usage of fragments with: the application of widely used standards, the providing of a tool support, and the adoption of a MOA providing an open and distributed architecture.

The current implementation of our approach allows method engineers to create method services. For now, we do not integrate the corresponding user interface with method services (back office services). These services may be used to modify existing methods or create new ones with BPEL processes. A limitation of our work is the implementation of the composition principle as we can only implement assembly composition without overlapping. This principle is a very big technical issue on which we are currently working.

Our future works include implementing the semantic part of method services and defining a way for characterising the specific project situation. Our aim is to build both the CASE tool based on SaaS for supporting new methods (created by the application of ME approaches) and the CAME tool for method engineers for composing method services using the semantic descriptors.

Fig. 1 .

 1 Fig. 1. Method fragments' comparison framework.

Figure 2 Fig. 2 .

 22 Fig. 2. Meta models parts of the reviewed fragment types.

Fig. 3 .

 3 Fig. 3. Meta model of a method service fragment.

Fig. 4 .

 4 Fig. 4. Method Oriented Architecture.

Fig. 5 .

 5 Fig. 5. Objectify Method Service Semantic Descriptor.

•Fig. 6 .

 6 Fig. 6. Objectify Method Service Application Example.

Table . 1

 . . Standards used for resolving the technical issues.


Pierre Courrieu
email: pierre.courrieu@univ-provence.fr

Michel Lequeux

ANAGRAM EFFECTS IN VISUAL WORD RECOGNITION

Keywords: Visual Word Recognition, Orthographic Similarity, Anagram, Letter Codes, Translation Invariance

Four experiments using a lexical decision task showed systematic effects of the anagram relationship between lexical units as well as between prime and target stimuli, even though the letter strings had no common letters in the same position. An "anagram frequency effect", similar to the well known "neighborhood frequency effect", was observed in Experiment 1. An anagram priming effect was observed in Experiment 4. An anagram prime x lexical anagram interaction effect was observed in Experiments 2 and 3. We concluded that the mental lexicon is activated by position-free letter codes, together with other units that separately encode the order information.

What exactly is the "orthographic similarity" of words, or letter strings, for human readers? The answer to this question is essential for modeling word recognition processes, as well as for methodological purpose. The hypothesis that some kind of holistic process contributes to word recognition received some supporting evidence [START_REF] Allen | Holism revisited: evidence for parallel independent word-level and letter-level processors during word recognition[END_REF][START_REF] Lété | Word-shape and word-lexical-frequency effects in lexical-decision and naming tasks[END_REF], however, there is also a large amount of empirical evidence that analytical processes play an essential role [START_REF] Mcclelland | Preliminary letter recognition in the perception of words and non-words[END_REF]. As a consequence, most current models of word recognition postulate that the access to the mental lexicon is mediated by the recognition of component orthographic units such as letters. Given that a word is an ordered sequence of letters, and that human readers can discriminate anagrams, one must of course assume that some perceptual mechanism takes into account letter order information. There are a priori various possible ways of doing this, leading to very different word recognition models. The Interactive Activation Model [START_REF] Mcclelland | An interactive activation model of context effects in letter perception: Part 1, an account of basic findings[END_REF], as well as the Activation-Verification Model [START_REF] Paap | An activation-verification model for letter and word recognition: the Word-Superiority-Effect[END_REF], assumes that the letters are extracted from the visual stimulus by independent and position specific processing channels working in parallel. As a result, the letter codes are also position specific, with the consequence that the word MEAN = {(M, 1), (E, 2), (A, 3), (N, 4)} and its anagram NAME = {(N, 1), (A, 2), (M, 3), (E, 4)}, for example, have no common elements. A major difficulty with this type of approach is that it requires that a visual pre-processing be able to segment the stimulus into portions of image corresponding to the component letters to be recognized, before assigning each portion to the appropriate processing channel. This is possible only if there are topological or geometrical criteria that allow for suitable segmentation of the stimulus. This is the case if one considers only printed words where letters are not connected. However, human readers can also read strings of connected P. Courrieu & M. Lequeux / Anagram Effects 4 / 40 characters (cursive handwriting,Arabic writing,etc.), and in this case, one can hardly hope to find a suitable segmentation pre-process (see Manso De Zuniga, [START_REF] De Zuniga | Additive and interactive effects of repetition, degradation, and word frequency in the reading of handwriting[END_REF][START_REF] Srihari | A multi-level perception approach to reading cursive script[END_REF]. It seems that the problem of connected characters can be effectively solved using another family of neuron-like models, namely the so-called "Neocognitrons" [START_REF] Fukushima | Character recognition with neural networks[END_REF][START_REF] Fukushima | Recognition and segmentation of connected characters with selective attention[END_REF][START_REF] Fukushima | Neocognitron: a neural network model for mechanism of visual pattern recognition[END_REF]. In recent versions of this model, a moving attentional window is involved in the successive extraction of different letters from the stimulus image. The letter codes thus made available are position-free, and the position of each extracted letter can only be known by taking into account the visual location of the attentional window at the time where the letter was extracted. Hence, the identity and the position of letters are clearly dissociated in this type of model.

The Neocognitrons exhibited some qualitatively interesting performance in the perceptual analysis of printed as well as handwritten materials. However, the serial recognition of letters leads to unrealistic predictions in terms of processing time, although there are some empirical supporting arguments for the hypothesis of a serial component in the perceptual analysis of words [START_REF] Courrieu | Serial analysis in the perceptual discrimination of words[END_REF][START_REF] Courrieu | Perceptual analysis of words in Arabic[END_REF]. Another possibility is that the letters are extracted together with their local context, in the form of a set of small overlapping multiletter units such as bigrams or trigrams [START_REF] Seidenberg | A distributed, developmental model of word recognition and naming[END_REF]. For example, MEAN = {(_ME), (MEA), (EAN), (AN_)}, where '_' stands for the space character, is a possible representation using trigrams. However, one must take care that the size of an alphabet of trigrams is in the order of 27 3 = 19683, and even if one removes impossible trigrams, this is not an economical code. The size of an alphabet of bigrams is in the order of 27 2 = 729, which seems more reasonable and compatible with the number of input connections of biological neurons. One can also imagine that only certain particularly relevant trigrams are encoded together with bigrams. It is obvious that one can develop many variants of the above models in order to improve their performance or to account for particular empirical results (Jacobs & Grainger, 1992;[START_REF] Mcclelland | The programmable blackboard model of reading[END_REF]Segui & Grainger, 1990). Note, however, that each basic hypothesis concerning the nature of orthographic codes induces a particular topology for the space of letter strings, and thus, the orthographic similarity can be defined in very different ways depending on the specific basic model. For example, if one considers position-specific letter codes as in the Interactive Activation Model, then two distinct letter strings are maximally similar if they are made of the same letters at the same positions except one (e.g. DEADLINE-HEADLINE), which corresponds to "orthographic neighbors" in the sense of [START_REF] Coltheart | Access to the internal lexicon[END_REF]. In this framework, anagrams cannot be orthographic neighbors, since they differ by at least two orthographic units. However, if one considers position-free letter codes, as in Neocognitrons, two anagrams are in fact made of the same orthographic units, and thus are in some way similar, while the order information must be coded separately.

A variety of studies have addressed the issue of position-specific letter codes (for a review, see [START_REF] Courrieu | L'influence du voisinage orthographique lors de la reconnaissance des mots écrits[END_REF]. One of the most famous observed effects is the so-called "neighborhood frequency effect" [START_REF] Grainger | On the role of competing word units in visual word recognition: the neighborhood frequency effect[END_REF][START_REF] Fukushima | Character recognition with neural networks[END_REF]Grainger & Segui, 1990;Jacobs & Grainger, 1992). For example, in a lexical decision task, it was observed that the response time to a word with at least one orthographic neighbor (in the sense of [START_REF] Coltheart | Access to the internal lexicon[END_REF] of higher frequency of use than itself is longer than the response time to a word with the same frequency of use but lacking a more frequent orthographic neighbor. In an Interactive-Activation framework, neighborhood frequency effects can be interpreted in terms of inhibiting connections between lexical nodes representing orthographic neighbors, with the nodes of the most frequent

P. Courrieu & M. Lequeux / Anagram Effects 6 / 40
words being activated more quickly by the input and thereby producing temporary inhibition of the less frequent neighbors. In an Activation-Verification framework, neighborhood frequency effects can be interpreted in terms of the joint activation, by the input, of several orthographic neighbor candidates, which would be checked one by one in decreasing order of frequency of use until the correct candidate is identified.

However, the idea of absolute position-dependent letter codes is incompatible with certain results obtained in perceptual identification and lexical decision experiments with masked orthographic priming [START_REF] Humphreys | Orthographic processing in visual word identification[END_REF][START_REF] Peressotti | The role of letter identity and letter position in orthographic priming[END_REF]. For example, it was observed that the prime BLCN facilitated the recognition of the target French word BALCON as well as the prime B-LC-N, while the prime NLCB did not produce facilitation.

Hence, the letter positions must be encoded in a relative way instead of an absolute one. In this case, the orthographic neighborhood, in the sense used above, is only a particular case of orthographic similarity, and one can find more suitable measures of the orthographic similarity such as, for example, the socalled "edition distance" based on a Dynamic Programming approach [START_REF] Wagner | The string to string correction problem[END_REF]. Recent models of relative letter position coding use "openbigrams" as coding units [START_REF] Grainger | Modeling letter position coding in printed word perception[END_REF][START_REF] Schoonbaert | Letter position coding in printed word perception: effects of repeated and transposed letters[END_REF][START_REF] Whitney | How the brain encodes the order of letters in a printed word: The SERIOL model and selective literature review[END_REF]. Open-bigrams are ordered pairs of adjacent or non-adjacent letters of the string. As an example, in the string CART, the set of open-bigrams is {CA, CR, CT, AR, AT, RT}. These models are based on the principle of "spatial coding" [START_REF] Grossberg | A theory of human memory: Self-organization and P. Courrieu & M. Lequeux / Anagram Effects 35 / 40 performance of sensory-motor codes, maps, and plans[END_REF], where the activation level of a detected letter depends on its position, and this activation level decreases from the left-most positions to the right-most positions, or, more generally, following the writing direction of the considered language, as suggested by recent data [START_REF] Kwantes | Letter encoding in visual word identification: more evidence for a word-integration explanation for parafoveal effects in reading[END_REF]. Then the models transform the relative activation of letters into an activation of open-bigrams [START_REF] Whitney | How the brain encodes the order of letters in a printed word: The SERIOL model and selective literature review[END_REF]. Note that relative position coding models are compatible with the idea of position-free letter codes, but these ones are not assumed to be directly used for lexical access.

There are also some empirical evidences concerned with the idea that position-free letter codes could be used for lexical access. [START_REF] Chambers | Letter and order information in lexical access[END_REF] observed interference effects between close anagrams (e.g. BALE-ABLE), and these effects were confirmed in lexical decision and naming tasks by [START_REF] Andrews | Lexical retrieval and selection processes: Effects of transposed-letter confusability[END_REF], who proposed an interpretation in terms of approximate coding of letters' position, as also predicted by [START_REF] Ratcliff | A theory of order relations in perceptual matching[END_REF]'s theory. The similarity of close anagrams can be suitably measured using an extended version of the edition distance [START_REF] Lowrance | An extension of the string-to-string correction problem[END_REF]. [START_REF] Courrieu | Des lettres sans position dans la perception des mots [Unpositioned letter codes in the perception of words[END_REF], using a lexical decision task with masked orthographic priming and a masked target (40 ms SOA), found that the probability of identifying a target word (that had no lexical anagrams) was modified whenever the prime was a non-word anagram of the target, although the prime and the target never had their common letters at the same position and were not close anagrams. Anagram priming effects depended on the structure of the anagram in a way that suggests a particular role of bigrams in the encoding of order information, while the distance of transposed letters per se did not appear relevant. Taking into account a few bigrams is commonly sufficient for solving an anagram. For example, the presence of the bigram 'EA' in the string MEAN excludes its anagrams NAME, MANE, and AMEN. In fact, one knows that certain small multi-letter units (functional spelling units) may play an important role in the phonological encoding of letter strings [START_REF] Pring | Phonological codes and functional spelling units: reality and implications[END_REF]. On the other hand, certain observations of (voluntary) anagram solving processes strongly suggested that the integration of letter strings is linked to their phonological encoding [START_REF] Fink | The use of phonemic information to solve anagrams[END_REF], and it seems that phonological encoding can occur quite rapidly (but later than orthographic encoding) in visual word recognition [START_REF] Ziegler | Visual and phonological codes in letter and word recognition: Evidence from incremental priming[END_REF]. [START_REF] Perea | Can CANISO activate CASINO? Transposedletter similarity effects with nonadjacent letter positions[END_REF] found anagram priming effects, in a lexical decision task, with nonadjacent transposed letters. However these effects were detectable for target words only when the transposed letters were consonants, while transposed vowels did not provide priming for words, and provided only weak priming effects for non-words. Given that the distinction between consonants and vowels is of phonological nature, this suggests a possible role of a phonological coding in the processing of letter order, however other explanations are possible in terms of a modified openbigram theory.

While most studies focused on the question of how letter order is encoded, there is little data concerning the consequences of a possible use of positionfree letter codes (as in Neocognitrons) for lexical access, despite the suggestive fact that 91% of the words do not have lexical anagrams, in French and in English as well [START_REF] Deloche | Order information redundancy of verbal codes in French and English: neurolinguistic implications[END_REF], and thus only 9% of the words theoretically require the order information to be taken into account (see also [START_REF] Shillcock | Eye-fixation behavior, lexical storage, and visual word recognition in a split processing model[END_REF]. The present study provides some new data concerning the hypothesis that position-free letter codes are used in lexical access. Note that the hypothesis is not that the order information is not taken into account, but that the letter position, as additional information, is not directly available in letter codes, which are assumed to be translation invariant (and also invariant through some other geometrical transformations, according to Neocognitron models). In this framework, it is clear that the anagram relationship, within the lexicon or between stimuli, constitutes a form of orthographic similarity whose effects on reading performance should be detectable. However, Neocognitrons are pure visual analyzers, they do not use any orthographic constraint, and to date, no lexical stage has been P. Courrieu & M. Lequeux / Anagram Effects 9 / 40 implemented in these models. Hence, specific predictions concerning lexical access can only be derived from the properties of their output neurons, which correspond to translation invariant letter codes. A possible strategy consists of reproducing some well-known orthographic similarity effects, such as the neighborhood frequency effect, while using the anagram relationship as the orthographic similarity factor. One can also attempt to interpret the observed effects in the framework of well-known word recognition models, replacing their position-specific letter codes by position-free letter codes. This is addressed in the following four experiments.

EXPERIMENT 1

The purpose of this experiment was to provide evidence of an "anagram frequency effect" analogous to the well known "neighborhood frequency effect" in a lexical decision task. The potential interpretations of these effects differ only by the position-free nature of the underlying letter codes.

Method

Participants

Twenty-four university students (12 women and 12 men) volunteered to participate in the experiment. Their native language was French, and they all had normal or corrected-to-normal vision.

Material

The stimuli were twenty-eight 5-letter words and twenty-eight, regular 5-letter pseudo-words written in lowercase letters with the necessary French diacritical marks. An additional 12 words and 12 pseudo-words were used for training the participants to the task. The frequency of use of each test word was controlled using the logarithm of the absolute frequency given in the Trésor de la Langue Française ( T.L.F.) (1971). On this scale, the log-frequencies range from 0, for words which occurred only once in the corpus of 70,317,234 occurrences of the T.L.F., to 12.9 for the most frequent words (e.g. the French preposition "de" (of)). The lexical anagrams of the test words were controlled in reference to the Larousse du Scrabble (1978). The number of orthographic neighbors (N-count) of the stimuli was also controlled. The 28 test words were divided into 4 categories of 7 words each. This gave us (1) 7 frequent words, each of which was the most frequent of a set of 3 lexical anagrams, (2) 7 infrequent words each of which was the least frequent of a set of 3 lexical anagrams (the anagrams in these sets were never the same as those in the frequent test word sets), (3) 7 frequent words with no lexical anagrams (other than themselves), and (4) 7 infrequent words with no lexical anagrams (other than themselves).

The last two categories were matched in frequency to the first two. The logfrequency and N-count statistics of the material are given in Table 1. An analysis of variance on the N-counts showed no significant differences across conditions (all F's < 1).

Procedure

The stimuli were displayed in the center of a computer screen (50 Hz synchronized, rapid phosphorus cathodic screen). The letters in the stimuli were defined in a fixed 7x7 pixel matrix, and were presented in a light color on a dark background. The stimuli always subtended a visual angle of less than 2

P. Courrieu & M. Lequeux / Anagram Effects 11 / 40
degrees. A trial began with the display of a fixation point. Then a tone rang, and 500 ms later, the stimulus was displayed with the third letter placed at the fixation point. The participant was supposed to decide as quickly and as accurately as possible whether the stimulus was a word in the French language.

The lexical decision was entered by pressing a key marked "oui" (yes) or a key marked "non" (no). The participant's responses and response times (in ms) were recorded by the computer. The stimulus disappeared when the answer was given, and the next trial started 3 seconds later. The testing began with 24 practice trials of words and pseudo-words presented in a fixed, random order. These were followed by 56 trials of stimuli presented in random order, randomly varied across participants. non-anagram). The F-ratios for the participant population (F1) and the item population (F2) were computed. In addition, we computed Quasi-F ratios (F' formula), which provide a severe test of effects with respect to the participant and item populations simultaneously. Quasi-F ratio tests are suitable to experimental designs using sampled materials that cannot be counterbalanced [START_REF] Wickens | On the choice of design and of test statistic in the analysis of experiments with sampled materials[END_REF]Winer, 1971, pp. 357-378). In addition, the use of such a severe test, together with a preserved full random variance, prevents any abusive positive conclusion, particularly in the case of a relatively low experimental power (only 7 items per condition, due to selection constraints).

Results

The mean response times and percentages of correct responses are presented in 24)=5.60, p<.03) and marginally significant for the Quasi-F ratio (F'(1, 47)=3.13, p<.08). The observed significant interaction can thus be explained essentially by this last simple effect, so the obtained result is exactly the expected one, that is, one obtained an anagram frequency effect equivalent to the well known neighborhood frequency effect. The pattern of errors was similar to the pattern of response times, so no speed-accuracy tradeoff must be suspected, and there would be no justification to exclude error response times.

Discussion

These results indicate an anagram frequency effect analogous to the wellknown neighborhood frequency effect. This suggests that the anagram relationship can constitute another form of orthographic similarity, and thus that the orthographic codes used during lexical access cannot be reduced to position-specific letter codes. However, one could object that there is a possible bias connected to the fact that there is a non-negligible correlation between the number of lexical anagrams and the log-frequency of the individual letters in the words. Consequently, we checked the log-frequency of the letters in our experimental material (Table 3). The suspected correlation was confirmed: the As it is difficult in practice to separate the number of lexical anagrams from the frequency of letters, we did an a posteriori analysis of the partial correlations between the different explanatory variables and the response time. Remember that partial, three-variable correlations can be used to estimate two-variable correlations, the effect of the third variable being eliminated. The analyses were done separately for the two frequency levels, so that each correlation was computed on a set of 14 words. The variables studied were the response time (T), the number of lexical anagrams (A), which was 1 or 3 in our material, the number of orthographic neighbors (N), and the log-frequency of the individual letters (L). Let r(ij) denote the ordinary correlation between the variables i and j, and let r(ij/k) denote the partial correlation between the variables i and j when the variable k is kept constant. Table 4 presents the results of this analysis. As one can see in Table 4, there was a strong correlation between A and L for both the frequent (r=0.68, df=12, p<.01) and the infrequent words (r=0.76, df=12, p<.01), which simply corresponds to the bias reported above. For infrequent words, one observed a significant positive partial correlation between A and T a prime that is its anagram? In principle, all the lexical anagrams of the prime will be pre-activated, but if we agree with the general hypothesis of the Interactive Activation model, the more frequent candidates will inhibit the less frequent ones. This leads us to predict that an anagram prime will facilitate its more frequent lexical anagrams, whereas it will either facilitate to a lesser degree or inhibit the less frequent lexical anagrams. However, in cases where the prime has only one lexical anagram, it can only be facilitated because it has no inhibiting competitor. Before testing these predictions, we must consider the time course of processes in order to choose suitable SOAs. The overall processing of a letter string, or of a word, typically requires several hundreds milliseconds. So it is not clear that with very short SOAs, a prime will be processed before the target. It seems plausible that, in this case, the processing of the prime and the target will largely overlap, and thus the priming effects depend on the compatibility of the two processes, while our experimental reasoning is in terms of residual pre-activation and pre-inhibition. Thus it is clear that we must choose SOAs that are not too short in order to test the above predictions.

Method

Participants

Twenty-four university students (12 women and 12 men) volunteered to participate in the experiment. Their native language was French, and they all had normal or corrected-to-normal vision.

Procedure

The general characteristics of the experimental device were identical to those in Experiment 1. An experimental trial began with the display of a fixation point in the center of the screen. Then a tone rang, and 500 ms later, a string of 5 letters was displayed with the third letter placed at the fixation point. This stimulus (prime) remained on the screen for 200 ms, and was then masked by a string of 5 asterisks (which also remained on the screen for 200 ms) designed to prevent direct visual "correlations" across stimuli. Finally, the asterisks were replaced by a 5-letter stimulus that was either a word or a regular pseudo-word (target), and remained on the screen until the participant made a lexical decision (on the latter stimulus only) by pressing the yes or no key. The participant's responses and response times (in ms) were recorded. The test stimulus was erased as soon as the response was given, and the next trial began 3 seconds later. The testing began with 24 practice trials in a constant, random order. These were followed by 96 trials in a random order which varied randomly across participants.

Material

Three sets of sixteen, 5-letter test words (lowercase letters, with diacritical marks) were selected to be used as the second stimulus (target). Each set contained 8 frequent words and 8 infrequent words (see the log-frequencies in Table 5). Each word in sets 1 and 2 had between 1 and 3 anagrams (other than itself) in the French lexicon, and the two sets were balanced for the number of anagrams. The words in set 3 had no lexical anagrams. To each test word, one associated an anagram such that the common letters of the two strings never were at the same position. For the set 1, the associated anagram was always a

French word, while for sets 2 and 3 its was always a non-word. Each group of 8 words in each set was divided into two sub-groups of four words. In one of two

Results

The mean response times and correct response percentages are presented in Table 6. Given the counterbalanced experimental design, the data were input into two separate analysis of variance, one for participants and one for items.

The independent variables were the target frequency of use (frequent vs. infrequent), the type of prime (anagram vs. control), and the set (1, 2, 3).

Concerning the set factor, the opposition of the first set to the other two refers to the lexicality of the prime (word prime vs. non-word prime), whereas the opposition between the first two sets and the last one refers to the number of lexical anagrams of the target (lexical anagrams vs. no anagrams).

For response times, there was a significant effect of the test word's frequency of use (F1(1, 22)=33.81, p<.001; F2(1, 42)=14.98, p<.001), and a significant threeway interaction between the frequency of use, the type of prime, and the set (F1(2, 44)=5.26, p<.01; F2(2, 42)=3.97, p<.03). To analyze this interaction, the data for frequent and infrequent target words were separated. For the frequent words, there was no significant effect of the type of prime or the set. In contrast, for infrequent words, there was a significant interaction between the type of prime and the set (F1(2, 44)=4.18, p<.02; F2(2,21=3.69, p<.04). A significant partial interaction between the type of prime and the number of lexical anagrams of the target (i.e. (anagram vs. control) x ((set 1, set 2) vs. set 3))

was extracted (F1(1, 44)=7.85, p<.01; F2(1, 21)=6.93, p<.02), and the residual effect was non-significant (all F's < 1), i.e. the lexicality of the prime was not a relevant factor. Breaking down the significant partial interaction, one observed a non-significant facilitating effect (59 ms) of the anagram prime when the target word had lexical anagrams (F1(1, 22)=2.16; F2( 1, 14)=1.88), while there was a significant inhibiting effect (122 ms) of the anagram prime when the target word did not have lexical anagrams (F1(1, 22)=12.68, p<.002; F2(1, 7)=7.31, p<.03).

In addition, an analysis concerning only infrequent words with a control prime showed that infrequent words which had no lexical anagrams (sets 3) were recognized faster (125 ms) than those which had lexical anagrams (sets 1 and

2). This effect, which replicated the one observed in Experiment 1, was significant with respect to the participant population

Discussion

No significant effect of the anagram factors was observed for frequent target words. In contrast, these factors interacted for infrequent words in such a way that an anagram prime of the test word produced an inhibiting effect when the test word did not have lexical anagrams, while producing a non-significant facilitating effect when the test word did have lexical anagrams. This effect will be referred to as the "anagram-prime x lexical-anagram interaction effect". As in Experiment 1, the results are meaningless if one does not assume that positionfree letter codes are used in lexical access. The fact that frequent words appeared insensitive to the anagram factors could suggest that these words parallely benefit by another type of processing, however their impact on the processing of their infrequent lexical anagrams suggests that frequent words are not disconnected from the position-free letter processing system. It remains that the observed anagram-prime x lexical-anagram interaction effect was exactly the opposite of the one predicted by the Interactive-Activation hypothesis. Perhaps we would have better luck with the Activation-Verification hypothesis. On several occasions, effects have been observed suggesting that whenever an entry in the mental lexicon has triggered a false detection, diagnosed by a checking process, the lexical entry in question is temporarily inhibited (see for example [START_REF] Davelaar | Phonological recoding in lexical access[END_REF]. If this is true, then in cases where we present an anagram prime before a test word with no lexical anagrams, the unique lexical anagram of the prime (i.e. the test word) is activated, checking ensues, the error is diagnosed, and the lexical entry is inhibited, in such a way that when the corresponding word is actually presented an instant later, its recognition is slower due to residual inhibition.

However, if the test word has lexical anagrams which are more frequent than itself, these candidates would also be activated by the prime, and checked first, in such a way that if the SOA is not too long, the entry corresponding to the test word may not get checked before the test word appears. In this case it would be facilitated by anagram preactivation but would not be subject to the inhibition resulting from the checking process. The Activation-Verification hypothesis thus appears to account for the observed results, but if so, the SOA between the prime and the test word must be a critical factor.

EXPERIMENT 3

According to the Activation-Verification hypothesis formulated above, if we take situations similar to the ones used in Experiment 2 and modify the SOA between the prime and the test word, we can make the following predictions. A reduction in SOA should cause a reduction in the probability that candidates activated by the anagram prime will be checked. In this case, the inhibiting effects should disappear, and facilitating effects should appear. In contrast, an increase in SOA should increase the probability that inhibiting checking will take place before the presentation of the test word.

Method Participants

Thirty-two university students (16 women and 16 men) volunteered to participate in the experiment. Their native language was French, and they all had normal or corrected-to-normal vision.

Procedure

The procedure was the same as in Experiment 2, except that two SOAs were used, one shorter and one longer than in Experiment 2. With the short SOA, both the prime and the mask were displayed for 100 ms each. With the long SOA, both were displayed for 400 ms each. Each participant was tested under both SOA conditions, in succession, with the order of conditions reversed for half of the participants. Twenty-four practice trials preceded each condition.

Material

Two lists of sixteen, infrequent 5-letter words were selected, with the frequencies of use balanced across lists. The words in the first list all had lexical anagrams more frequent than themselves, while the words in the second list did not have lexical anagrams. For each word, a non-lexical anagram with no common letters at the same position was generated. This served as the anagram prime for the test word in one condition, and as the control prime for another word in another condition. The prime-target pairing was counterbalanced in the same manner as in Experiment 2. In all cases, the prime and the test word had no common letters in the same position. The assignment of the stimuli to the SOA conditions was also counterbalanced. The set of stimuli was completed with an equal number of distractors, which were regular, 5-letter pseudo-words equiprobably paired with an anagram or non-anagram prime.

Results

The mean response times and percentages of correct lexical decisions are given in Table 7. A significant overall interaction was found between the type of prime and the number of lexical anagrams of the test word (F1(1, 24)=6.49, p<.03; F2(1, 30)=5.42, p<.03).This interaction is a replication of the anagramprime x lexical anagram interaction effect found in Experiment 2 for infrequent words, and it did not depend significantly on the SOA. For the words with lexical anagrams, there was a non-significant interaction between the type of prime and the SOA (F1(1, 24)=3.99, p<.06; F2(1, 15)=1.55). The anagram prime had no detectable effect at the short SOA, and produced a non-significant facilitation effect (69 ms) with the long SOA. Note that these possible effects are in fact opposite to the expected ones. For words with no lexical anagrams, the effect of the anagram prime did not depend significantly on the SOA. There was an

P. Courrieu & M. Lequeux / Anagram Effects 24 / 40
overall inhibition effect (74 ms), significant for the participant analysis (F1(1, 24)=7.03, p<.02), and marginally significant for the item analysis (F2(1, 15)=3.27, p<.09).

Discussion

The SOA effects predicted by the Activation-Verification hypothesis were not obtained, while the anagram-prime x lexical anagram interaction effect observed in Experiment 2 was replicated in Experiment 3, and it appeared to be independent of the SOA. We are thus dealing with quite robust anagram effects, consistent with the use of position-free letter codes in lexical access.

Neither the Activation-Verification model nor the Interactive Activation model is able to predict the observed results, even when the assumed nature of the letter codes is modified.

EXPERIMENT 4

In Experiments 2 and 3, we observed non-significant tendencies for an anagram prime to facilitate the recognition of infrequent words possessing lexical anagrams. These tendencies were observed only at the longest SOAs.

However, we suspected that this was not linked to the SOA per se, since facilitating anagram priming effects have previously been observed with a masked priming technique at a SOA of only 40 ms (Courrieu, 1985, Exp. 2). On the other hand, in the present Experiments 2 and 3, a number of participants said that the prime was a hindrance and that they attempted to ignore it. In Experiment 4 we ask: what happens whenever an anagram prime is fully processed? This can be obtained if the participants must provide a response on the prime as well as on the target.

Method Participants

Thirty-two university students (16 women and 16 men) volunteered to participate in the experiment. Their native language was French, and they all had normal or corrected-to-normal vision.

Material

The stimuli were all 5 characters long and written in lowercase letters with the necessary diacritical marks. We selected 10 pairs of words that were anagrams of each other but had no common letters in the same position. In each pair, one of the two words was always much more frequent than the other. The logfrequency means (and standard deviations) were 8.59 (1.35) and 5.15 (1.16), respectively. In half of the anagram pairs, the more frequent word occurred first, and in the other half, the less frequent word came first. The ordering of the pairs was reversed for half of the participants, in such a way that for the experiment as a whole, each item occurred the same number of times in first or second position. This material was completed with 15 anagram pairs, from which 5 pairs pseudo-word+word, 5 pairs word+pseudo-word, 5 pairs pseudo-word+pseudo-word. The pseudo-words were regular, and the words were sampled over a large range of frequencies. In addition, 24 non-anagram practice pairs were included.

Procedure

A self-presentation procedure was used in this experiment. An experimental trial started with the display of a string of 5 asterisks in the center of the computer screen. Then a tone rang to announce that the trial could begin. The participant was supposed to display the first stimulus by pressing the yes key. This caused the first stimulus to replace the asterisks, then the participant was supposed to quickly strike the yes or no key to state whether or not the stimulus was a word in the French language. As soon as this lexical decision was entered, the stimulus was replaced by a new string of 5 asterisks, and the participant displayed the second stimulus by pressing the yes key. Then a new lexical decision was entered as quickly as possible, the stimulus disappeared, and the next trial began 3 seconds later. The participant's responses and response times (in ms) were recorded. The 24 practice trial pairs were presented in a constant, random order, followed by 25 pairs in a random order that varied randomly across participants.

Results

Since the experimental design was counterbalanced, separate analysis of variance for participants and items were performed. These analysis concerned the word+word anagram pairs. The independent variables were the relative frequency of use of the word (more frequent, less frequent) and its rank in the display sequence (first, second). The first rank was the control, and the second rank was the "primed" rank.

The mean response times and percentages of correct lexical decisions are given in Table 8. For the response times, the main effect of the frequency of use was significant (F1(1, 30)=48.66, p<.001; F2(1, 18)= 18.59, p<.001), the main effect of the rank was non-significant, and there was a marginally significant interaction between the frequency of use and the rank (F1(1, 30)=3.11, p<.09; F2(1, 18)=3.88, p<.07). Analysis of simple effects showed that the prior presentation of the less frequent anagram had no significant effect on the recognition time of the more frequent anagram (all F's < 1), whereas the prior presentation of the more frequent anagram had a significant, facilitating effect (65 ms) on the recognition of the less frequent anagram (F1(1, 90)=6.35, p<.02; F2(1, 9)=6.62, p<.03).

Discussion

P. Courrieu & M. Lequeux / Anagram Effects

This final result showed that the presentation of a frequent word had a facilitatory effect on the subsequent recognition of its less frequent lexical anagram, even though the two words had no common letters in the same position. Note that this positive effect, which occurred when the frequent anagram was in fact presented, is the opposite of the negative effect observed in Experiment 1, where the more frequent anagram was not presented. We note also that the prior presentation of the less frequent anagram had no detectable effect on the subsequent recognition of the more frequent one. Given that the prime was fully processed in this experiment, one could suspect that some kind of anagram relationship based predicting strategy was used by the participants.

However, given that frequent words are a priori more predictable than infrequent words, a predicting strategy should have produced facilitatory effects on frequent anagrams at least as well as on infrequent anagrams, which does not match the observed pattern of results. Thus, a plausible interpretation is that frequent anagrams provide activation to their less frequent anagrams (anagram priming effect), while the opposite is not true. As we shall see below, this hypothesis also allows for understanding the anagram prime x lexical anagram interaction effect observed in Experiments 2 and 3, as well as (paradoxically) the anagram frequency effect observed in Experiment 1.

General Discussion

We found, in Experiment 1, an "anagram frequency effect" equivalent to the well known "neighborhood frequency effect" [START_REF] Grainger | On the role of competing word units in visual word recognition: the neighborhood frequency effect[END_REF][START_REF] Fukushima | Character recognition with neural networks[END_REF]Grainger & Segui, 1990;Jacobs & Grainger, 1992), that is, an infrequent word that has at least one frequent anagram was longer to recognize than a word of the same frequency of use that has no lexical anagram. This indicates that the anagram relationship is a kind of orthographic similarity, and thus, the concept of position-free letter codes is relevant in the context of the word recognition. We found, in Experiment 2, an "anagram prime x lexical anagram interaction effect" on infrequent target words, while frequent words appeared insensitive to the anagram priming. The structure of the observed interaction was inconsistent with the Interactive-Activation hypothesis, while the Activation-Verification hypothesis provided a possible interpretative framework, and predicted an interaction with the SOA. This prediction was tested in Experiment 3, where the anagram prime x lexical anagram interaction observed in Experiment 2 was replicated and appeared independent of the SOA. Hence the Activation-Verification hypothesis failed to explain the results. The structure of the anagram prime x lexical anagram interaction observed in Experiments 2 and 3 was such that an infrequent word that had no lexical anagram was strongly inhibited by an anagram prime, while an infrequent word that had at least one more frequent anagram in the lexicon was not inhibited by an anagram prime, and we even observed a non-significant facilitatory effect of the anagram prime at the longest SOAs. In Experiment 4, we used a procedure that implies full processing of the prime, and we observed that the prior presentation of a frequent anagram word significantly facilitated the subsequent recognition of one of its less frequent lexical anagrams, while the prior presentation of an infrequent anagram did not influenced the subsequent recognition of its more frequent anagram. To provide a coherent interpretative framework to all these results, we consider first the inhibitory effect of an anagram prime on words that have no lexical anagrams (Exp. 2 and 3). This effect shows two things. Firstly, of course, two anagram strings are not perceptually independent, even though they have no common letters at the same position. Secondly, order information, whenever it is different in the prime and the target, has a strong inhibitory effect.

These conclusions are similar to those drawn from previous results [START_REF] Courrieu | Des lettres sans position dans la perception des mots [Unpositioned letter codes in the perception of words[END_REF]. However, why does the inhibitory effect of the anagram prime vanish whenever the target word has a frequent lexical anagram? We sketch here the outline of a possible model.

Assume that each time that a new word is learned, within the mental lexicon, the following occurs. If the new word does not look like any other known word, then the new word receives a complete description, that is, its node receives all appropriate connections from lower level processing units. If the new word looks like some previously learned words (say its "big brothers"), then the nodes corresponding to these words are partially activated by the new stimulus.

Hence, instead of receiving a full description, the new processing unit receives activating input connections from its big brothers' nodes, and only a few additional input from lower level processes, in order to encode its difference from its big brothers. This is an economical way of connecting a network since it allows for reusing previously learned information, while encoding only the new information (and thus the total number of connections tends to be minimal). In addition, we must make some minimal assumptions concerning the input of lexical nodes. In account of the well-known word frequency effect, we assume that the activating input connections of frequent words are more strongly weighted than those of infrequent words. We assume that lexical nodes can receive connections from simple units such as position-free letter nodes, as well as from more complex units, such as open-bigrams or phonological codes, or any other units that encode the order information. According to the hierarchical complexity organization principle of Neocognitron type models, we assume that small units such as position-free letters are available sooner, in the perceptual analysis of a stimulus, than more complex units (bigrams, phonological codes).

We note, however, that the hypothesis of multi-letter units can as well be replaced by another way of encoding the order information, provided that the letter codes themselves remain position-free, and available sooner than order information. Now, how can we understand the observed effects in such a theoretical framework? Given that frequent words have many chances to be learned before infrequent words, the big brothers are in general the most frequent words. If an infrequent word has at least one big brother, then it receives a large part of its activation from the stimulus by the intermediate of the big brother nodes, while if it does not have big brothers then it is directly activated by the perceptual analysis of the stimulus. The delay introduced by the big brother node mediation can explain the "anagram frequency effect" (Exp. 1), as well as the well known "neighborhood frequency effect". Now assume that a prime that is anagram of two words is presented. The most frequent anagram word is activated by position-free letter nodes, and then it provides activation to the less frequent anagram, while the order information directly provides a reduced amount of inhibition to the less frequent anagram node given that this one is poorly connected to the perceptual analyzers.

Depending on the relative amount of activation and inhibition it received, the less frequent anagram node can be in various states when the corresponding word is actually presented. The situation is different for an infrequent word that does not have big brothers because its node is richly connected to the perceptual analyzers. Thus when the anagram prime is presented, the node receives some activation from position-free letter nodes, and then it receives a full inhibition from order information processing units (such as open-bigram nodes, phonological nodes, etc.). This could explain the anagram prime x lexical anagram interaction effect observed in Experiments 2 and 3. The fact that frequent words are not sensitive to anagram priming (Exp. 2) could simply mean that their activating input approximately counterbalances their inhibitory input, while infrequent words without a big brother are more sensitive to inhibitory information since, as a result of their low frequency of use, their activating connections are weakly weighted. Finally, when a big brother is fully activated, it provides a large amount of activation to its less frequent anagrams, which explains the anagram priming effect observed in Experiment 4. As one can see, the proposed framework allows for a coherent interpretation of the results, which of course does not mean that this is necessarily the truth.

However, it seems that a firm conclusion can be drawn concerning the role of position-free letter codes, since robust effects were observed that do not make sense without this hypothesis.

Conclusion

The anagram relationship was shown to be a strong orthographic similarity factor for human readers, and this similarity produced robust effects on word recognition performance, even though the anagrams did not have any of their common letters at the same position. This implies that position-free letter codes are used for accessing the mental lexicon, while the letter order information is also taken into account, but in a separate way. These findings have theoretical as well as methodological implications. In particular, it seems desirable to build a suitable orthographic similarity measure in order to reliably control the confusability of experimental materials.

Table 1 .

 1 Mean log-frequency of use and number of orthographic neighbors (with standard deviation) of the test words used in Experiment 1.

		Anagrams	Non Anagrams
	Frequent words
	log-frequency of use	9.04 (0.60)	9.02 (0.63)
	N-count	2.29 (1.60)	3.00 (2.77)
	Infrequent words
	log-frequency of use	4.96 (0.52)	4.90 (0.69)
	N-count	3.00 (0.82)	2.57 (1.81)
	Statistical Analysis

Table 2 .

 2 The response times were significantly shorter for the frequent words

	than for the infrequent ones (F1(1, 23)=18.25, p<.001; F2(1, 24)=44.04, p<.001;
	F'(1, 28)=15.38, p<.001). No significant main effect of the number of lexical
	anagrams was observed, but there was a significant interaction between the
	number of lexical anagrams and the frequency of use (F1(1, 23)=6.52, p<.02;
	F2(1, 24)=5.61, p<.03; F'(1, 23)=4.28, p<.05). Analysis of the simple effects
	showed that the number of anagrams did not have a significant effect on the
	response time to frequent words (all F's < 1), but the infrequent anagrams took

more time to recognize than infrequent non-anagrams. This effect was significant for participants and items alike (F1(1, 69)=4.17, p<.05; F2(1, P.

Courrieu & M. Lequeux / Anagram Effects 13 / 40

Table 2 .

 2 Mean response time (ms) and percentage of correct lexical decisions in Experiment 1.

		Anagrams	Non Anagrams
	Frequent	575 (100%)	598 (99%)	587 (99%)
	Infrequent	721 (93%)	667 (96%)	694 (95%)
		648 (97%)	632 (98%)

  Finally, the errors varied in the same way as the response times.

	P. Courrieu & M. Lequeux / Anagram Effects	20 / 40
	p<.08). The residual comparison (set 1 vs. set 2) was not significant (all F's <
	1). Table 6. Mean response time (ms) and percentage of correct lexical decisions
	in Experiment 2.
		Set 1	Set 2		Set 3
		Anagrams	Anagrams	Non Anagrams
		Word prime	Nonword prime	Nonword prime
	Frequent word
	Anagram prime	667 (95%)	649 (99%)		629 (95%)
	Control prime	680 (97%)	616 (96%)		639 (100%)
	Infrequent word
	Anagram prime	732 (93%)	738 (86%)		792 (82%)
	Control prime	765 (93%)	824 (83%)		670 (94%)

(F1(1, 44)=5.73, p<.02), and marginally significant with respect to the item population (F2(1, 21)=3.38,

Table 7 .

 7 Mean response time (ms) and percentage of correct lexical decisions in Experiment 3.

		Anagram word	Non anagram word
	Short SOA
	Anagram prime	809 (94%)	857 (94%)
	Control prime	807 (94%)	794 (95%)
	Long SOA
	Anagram prime	756 (96%)	860 (94%)
	Control prime	825 (94%)	776 (96%)

Table 8 .

 8 Mean response time (ms) and percentage of correct lexical decisions

	in Experiment 4.
		Most frequent anagram Less frequent anagram
	First	763 (99%)	918 (94%)
	Second	773 (99%)

 for L constant (r=0.55, df=11, p<.05), which shows that the anagram frequency effect was independent of the letter frequency effect. Moreover, the partial correlation between L and T for A constant was negative (r= -0.35, n.s.), that is, A and L tended in fact to have opposite effects on the response time. No significant effect of N on T was detected, however this results from the fact that the material of this experiment was not selected in order to allow the detection of neighborhood effects. Table 4. Correlations between the log-frequency of letters (L), the number of lexical anagrams (A), the number of orthographic neighbors (N), and partial correlations of these variables with the response time (T) in Experiment 1. Note that r(xT/y) denotes the partial correlation between x and T for y constant. Frequent anagrams: poser, sacré, lampe, santé, perdu, cause, voile.

Infrequent anagrams: opter, rouet, rebut, piler, urine, store, piton.

Frequent non anagrams: juger, digne, choix, nuage, moral, forme, jouir.

Infrequent non anagrams: miner, canif, cible, cuver, magot, bocal, purge.

Experiment 2.

The pairs (prime-test word) are presented in anagram pairing.

Set 1, frequent test: acier-craie, sceau-cause, sueur-usure, aimer-maire, crédo-décor, trois-sorti, repos-prose, merci-crime.

Set 1, infrequent test: P. Courrieu & M. Lequeux / Anagram Effects éclat-lacté, ouest-soute, porte-opter, sueur-usure, brute-rebut, repos-prose, tiers-strie, jeune-enjeu, perdu-duper, acier-carie.