J E Kim

C Bouchard

J F Omhover

A Aoussat

Towards a model of how designers mentally categorise design information

Keywords:

This study aims to explore how designers mentally categorise design information during the early sketching performed in the generative phase. An action research approach is particularly appropriate for identifying the various sorts of design information and the cognitive operations involved in this phase. Thus, we conducted a protocol study with eight product designers based on a descriptive model derived from cognitive psychological memory theories. Subsequent protocol analysis yielded a cognitive model depicting the mental categorisation of design information processing performed by designers. This cognitive model included a structure for design information (high, middle, and low levels) and linked cognitive operations (association and transformation). Finally, this paper concludes by discussing directions for future research on the development of new computational tools for designers.

Introduction

Developments in science and technology dating to the industrial revolution have been of great research interest; however, historical accounts have paid relatively little attention to the role of consumers/users and designers. Since the widespread introduction of the notion of ''user-centred design'' during the late 1990s, research on consumers in the service of enhancing interface design, improving usability, etc. has become common. Nowadays, during the transition from a knowledge society to a creative society, research into the cognitive activities of designers, important contributors to the generation of the creative ideas that underpin efforts to meet consumers' needs and desires, has been growing and has led to a substantial increase in the value assigned to certain domains [START_REF] Brown | Design Thinking[END_REF][START_REF] Resnick | Sowing the Seeds for a More Creative Society[END_REF][START_REF] Restrepo | Information Processing in Design[END_REF]. Indeed, the expertise and the cognitive and creative processes of designers during the early stages of design have been acknowledged as important research foci. At the same time, designers have developed digital design databases, which have become increasingly important parts of their work as a result of the dissemination of information technology (IT) [START_REF] Bouchard | TRENDS: A Content-based Information Retrieval System for Designers[END_REF][START_REF] Bu ¨sher | Designs on Objects: Imaginative Practice, Aesthetic Categorization and the Design of Multimedia Archiving Support[END_REF][START_REF] Pasman | Designing With Precedents[END_REF][START_REF] Restrepo | Information Processing in Design[END_REF].However, the development of computational tools for designers has been limited to prototyping technology such as Computer Aided Design (CAD), Computer-aided Manufacturing (CAM), or Computer-aided Styling (CAS), because the activities of designers are relatively implicit and subjective and involve rich mental representations during the early stages of the design process [START_REF] Ullman | A Model of the Mechanical Design Process Based on Empirical Data[END_REF].

In this context, our study was designed to develop new models and tools to be used to digitise this early design process according to the three progressive steps: [START_REF] Akin | How Do Architects Design? Artificial Intelligence and Pattern Recognition in Computer Aided Design[END_REF] to identify the design knowledge, rules, and skills that underpin designers' cognitive processes [START_REF] Rasmussen | Skills, Rules and Knowledge: Signals, Signs and Symbols, and Other Distinction in Human Performance Models[END_REF]; [START_REF] Atkinson | The Control of Short-term Memory[END_REF] to translate the design rules into design algorithms; and (3) to develop computational tools for use by designers themselves and by other professionals involved in the early collaborative design process [START_REF] Bouchard | TRENDS: A Content-based Information Retrieval System for Designers[END_REF].

This paper focuses on the first step in particular, which involves modelling those aspects of a designer's cognitive process that are dedicated to the mental categorisation of the design information used during the generative phase. We applied an action research approach which is a form of reflexive process in encompassing both theoretical and practical concerns while contributing a scientific method or a model [START_REF] Liu | Fondements et pratiques de la recherche-action[END_REF]. This approach enabled us not only to build a model of the cognitive processes used by designers, but also to rely on both theoretical and experimental approaches to elicit the specific cognitive activities used by designers (see Fig. 1). First, we reviewed the scientific literature on the cognitive processes of designers from the perspectives of both design science and cognitive psychology in Sections 2.1 and 2.2.A descriptive model of information processing involving memory theories drawn from cognitive psychology is presented in Section 2.3. This model was refined and enriched via a protocol study with eight product designers, as discussed in Sections 3 and 4. Finally, Section 5 synthesises the results of a subsequent protocol analysis within the framework of a cognitive model depicting the mental categorisation of design information processed by designers.

Theoretical background

Understanding the cognitive dynamics and information processing of designers during the early stages of design

The early stages of the design process have been characterised in terms of information processing and idea generation (also called ''conceptualisation'') [START_REF] Bonnardel | Towards Supporting Evocation Processes in Creative Design: A Cognitive Approach, Special Issue on Computer Support for Creativity[END_REF][START_REF] Bouchard | Development of a Kansei Engineering System for Industrial Design: Identification of Input Data for Kansei Engineering Systems[END_REF][START_REF] Bu ¨sher | Designs on Objects: Imaginative Practice, Aesthetic Categorization and the Design of Multimedia Archiving Support[END_REF][START_REF] Eckert | Sources of Inspiration: A Language of Design[END_REF]. During the early stages of the design process, designers integrate various levels of information to reduce abstraction by adding constraints [START_REF] Bonnardel | Towards Supporting Evocation Processes in Creative Design: A Cognitive Approach, Special Issue on Computer Support for Creativity[END_REF][START_REF] Bouchard | Development of a Kansei Engineering System for Industrial Design: Identification of Input Data for Kansei Engineering Systems[END_REF]. Bouchard et al. [START_REF] Bouchard | Development of a Kansei Engineering System for Industrial Design: Identification of Input Data for Kansei Engineering Systems[END_REF] and references therein, interpreted the cognitive processes of designers during the early stages in terms of information processing. According to this view, designers engage in an informational cycle that includes informative, generative, and decision-making phases (evaluation-selection) to produce intermediate representations (IRs) that develop in an evolutionary way. Goldschmidt [START_REF] Goldschmidt | On Visual Design Thinking: The Vis Kids of Architecture[END_REF] defined IRs as mental or physical images used during the entirety of the design process. IRs can be implicit or explicit, appearing as design briefs, trend boards, 2D/3D sketches, styling models, digital geometrical models, mock-ups, prototypes, etc. They are used strategically according to the design context, design phase, design purpose, cultural context, etc.

Given that the early stages of design are considered to be among the most cognitively intensive in the design process [START_REF] Nakakoji | Special Issue on 'Computational Approaches for Early Stages of Design[END_REF], several studies based on interior and architectural designs have been pioneered to understand the sketching activities of designers, especially those performed during the generative phase [START_REF] Bilda | The Impact of Working Memory Limitations on the Design Process During Conceptualization[END_REF][START_REF] Goldschmidt | On Visual Design Thinking: The Vis Kids of Architecture[END_REF][START_REF] Scho ¨n | Kinds of Seeing and Their Functions in Designing[END_REF][START_REF] Suwa | What Do Architects and Students Perceive in Their Design Sketches? A Protocol Analysis[END_REF]. Since the early 1990s, a few studies dedicated to the sketching activity of designers have emerged in mechanical engineering design; these include Ulman et al. [START_REF] Ullman | The Importance of Drawing in the Mechanical Design Process[END_REF], Goel [START_REF] Goel | Sketches of Thought[END_REF], Purcell and Gero [START_REF] Purcell | Drawings and the Design Process[END_REF], and Yang [START_REF] Yang | Observations on Concept Generation and Sketching in Engineering Design[END_REF]. To date, little research has addressed issues related to the inspirational sources used by designers in the informative phase [START_REF] Bouchard | TRENDS: A Content-based Information Retrieval System for Designers[END_REF][START_REF] Eckert | Sources of Inspiration: A Language of Design[END_REF][START_REF] Keller | For Inspiration Only -Designer Interaction with Informal Collections of Visual Material[END_REF]. Moreover, the bridge between the informative and earliest generative phases has been relatively neglected, and the specific experiences of product designers have not yet come to the fore.

Definition of the ''psychological processes whereby design information is categorised''

The bridge between the informative and earliest generative phases involves the generation of new ideas and new solutions. It begins with numerous mental images, memorised design briefs, and other information derived from previous design projects [START_REF] Bouchard | Development of a Kansei Engineering System for Industrial Design: Identification of Input Data for Kansei Engineering Systems[END_REF]. This process has been recognised as an individualised experience for designers that manifests in repetitive cognitive activities [START_REF] Jin | Study of Mental Iteration in Different Design Situations[END_REF]. During the earliest generative phase, certain parts of the mental images can be externalised in sketches. These early sketches are not mature or suitable to be shared with or interpreted or used by other people. Instead, they can serve as external representations (i.e., externalised memories that act as visual tokens during later inspection) [START_REF] Crilly | Representing Artefacts as Media: Modelling the Relationship Between Designer Intent and Consumer Experience[END_REF][START_REF] Goldschmidt | On Visual Design Thinking: The Vis Kids of Architecture[END_REF][START_REF] Prats | Transforming Shape in Design: Observations from Studies of Sketching[END_REF][START_REF] Suwa | What Do Architects and Students Perceive in Their Design Sketches? A Protocol Analysis[END_REF]. External representations (e.g., early sketches) allow a reflexive conversation between the designer and the product to be created [START_REF] Crilly | Representing Artefacts as Media: Modelling the Relationship Between Designer Intent and Consumer Experience[END_REF][START_REF] Suwa | What Do Architects and Students Perceive in Their Design Sketches? A Protocol Analysis[END_REF]. Previous studies have shown that external representations allow designers to identify errors that are then used to generate new ideas [START_REF] Akin | How Do Architects Design? Artificial Intelligence and Pattern Recognition in Computer Aided Design[END_REF]. Similarly Crilly et al. [START_REF] Crilly | Representing Artefacts as Media: Modelling the Relationship Between Designer Intent and Consumer Experience[END_REF] noted that designers engaged in ''bi-directional conversations'' with representations insofar as intentions were formed and reformed during the activities of representation (see also Scho ¨n's ''Seeing-Drawing-Seeing model'' [START_REF] Scho ¨n | Kinds of Seeing and Their Functions in Designing[END_REF]). External and internal information interact with each other in an evolutionary manner and are integrated and synthesised into categories contributing to design solutions via the designer's mental processing [START_REF] Bouchard | Development of a Kansei Engineering System for Industrial Design: Identification of Input Data for Kansei Engineering Systems[END_REF]. In this respect, we define this phase as involving the psychological process whereby design information is categorised during the sketching that occurs in the earliest generative phase. More precisely, our aim is to identify the kind of cognitive operations that extract design information from memory and to determine how this design information is transformed or categorised during early sketching. Towards this goal, the following section proposes an initial descriptive model of information processing that integrates memory models derived from cognitive psychology, which describe the transfer of information through memory, including those of Atkinson and Shiffrin [START_REF] Atkinson | The Control of Short-term Memory[END_REF], Baddeley et al. [START_REF] Baddely | Memory[END_REF], and Broadbent [START_REF] Broadbent | Perception and Communication[END_REF].

Proposal of a descriptive model of information processing

Broadbent [START_REF] Broadbent | Perception and Communication[END_REF] proposed a sequence of cognitive processing stages that can be performed in bottom-up or top-down order. Bottom-up processing is considered a stimulus-driven process caused by sensory stimuli, whereas top-down processing is seen as memory-driven. In many cases, stimulus-driven processes are based on inspiration such as photos, magazines, etc., which evoke feelings or emotions. Memory-driven processes are driven by knowledge derived from past experiences. In this paper, we focus particularly on memory-driven processes, which have received relatively less attention and thus remain less understood due to their implicit nature, characterised by information stored in memory as well as cognitive operations related to such information. We adapted two theoretical models drawn from cognitive psychology to formalise our examination: the model developed by Atkinson and Shiffrin [START_REF] Atkinson | The Control of Short-term Memory[END_REF] and that developed by Baddeley et al. [START_REF] Baddely | Memory[END_REF] (see Fig. 2).We selected cognitive operations related to six phenomena to account for overall information processing: stimuli, perceptual action, questioning, association, transformation, and judgment/decision. More specifically, operations involving questioning, associating, and transforming play roles in retrieving memorised design information from long-term memory (LTM) and moving it to working/short-term memory (WM/STM). According to the Geneplore Model defined by Finke et al. [START_REF] Finke | Creative Cognition-theory, Research, and Applications[END_REF] in the work of Benami and Jin [START_REF] Benami | Creative Stimulation in Conceptual Design[END_REF], several types of cognitive operations underpin the generative phase: retrieval of information from memory, association, mental synthesis, mental transformation, analogical transfer, and categorical reduction. Several of these, including mental synthesis and reduction, are difficult to categorically identify through verbalisations or sketches, but the remaining [ ( F i g . _ 2 ) T D $ F I G ] Fig. 2. Categorisation of design information during the earliest generative phase (description of an informational cycle [START_REF] Bouchard | Development of a Kansei Engineering System for Industrial Design: Identification of Input Data for Kansei Engineering Systems[END_REF]). three (retrieval of information from memory, association, and transformation) can usually be identified. The remaining operations (those pertaining to stimuli, perceptual action, and judgment/decision) were based on the model defined by Ball and O'Callaghan [START_REF] Ball | Judging the Accuracy of Children's Recall: A Statement-level Analysis[END_REF] and Harris [START_REF] Harris | Effect of Decision Making on Ultrasonic Examination Performance[END_REF]. Consequently, these six cognitive operations have been used to develop our coding scheme, which was the foundation of our definitions of the major cognitive operations involved in the mental categorisation of design information (Table 1 and Fig. 3).

[ ( F i g . _ 1 ) T D $ F I G ]
The descriptive model helps us to clarify and define what design is from a theoretical point [START_REF] Takeda | Modeling Design Processes[END_REF]. The following section describes our protocol study to identify the actual designer's activities dedicated the mental categorisation of the design information used during the generative phase.

Design of protocol study

The aim of our protocol study was to determine the kind of cognitive operations used to extract mental information from memory and to examine how this mental information is transformed or categorised during early sketching. The present protocol is partially based on our previous work on design information [START_REF] Kim | A Study on Designer's Mental Process of Information Categorization in the Early Stages of Design[END_REF]. We recently merged the previous coding scheme for design information with the new coding scheme for cognitive operations (see Table 1). The two complementary coding schemes allow us to link the extracted design information with the cognitive operations used to perform the extractions.

Methods

A comprehensive and varied research method is required for understanding information and activities related to design [START_REF] Cross | Analysing Design Activity[END_REF].In many cases, these methods have been based on the explicit representations used or produced by designers; therefore, they have certain limitations insofar as many of the cognitive activities of designers during the early stages of the design process are implicit. One approach to this issue is provided by methods drawn from ethnography. Data collected using an ethnographic methodology often derives from observations, interviews, and questionnaires completed in real contexts rather than from results of laboratory experiments. Another approach to this issue is provided by the think-aloud method, which is based on observations and verbalisations occurring in real time.

Generally two types of think-aloud methods have been used: concurrent and retrospective. The concurrent protocol could point out detail sequences of information process reflecting the designer's working memory (WM); therefore it has been utilised to reveal the process-oriented aspects of designing [START_REF] Dorst | Comparing Paradigms for Describing Design Activity[END_REF][START_REF] Ericsson | Protocol Analysis: Verbal Reports as Data[END_REF]. The retrospective protocol has been used in experimentations which focus on the cognitive content aspect because it could retrieve the trace of the cognitive process and reveal information partially in both working memory (WM) and long-term memory (LTM) [START_REF] Dorst | Comparing Paradigms for Describing Design Activity[END_REF][START_REF] Gero | Differences Between Retrospective and Concurrent Protocols in Revealing the Process Oriented Aspects of the Design Process[END_REF]. However, some methodological limitations still remain in both protocols: concurrent protocols may influence the natural design process and cause incompleteness in revealing the design (In watching the bicycle wheel) 'I had seen the mini-sports shoes on the bicycle wheel in the show window' Perceptual action Interpretation of visual information, such as depict elements on sketches for arranging the spatial relations on sketches [START_REF] Suwa | What Do Architects and Students Perceive in Their Design Sketches? A Protocol Analysis[END_REF] In profile, the screen should be this side for little more user-oriented, then a gripe on the right side Questioning An expression of inquiry about ideas and emerging issues not associating with one another Does it feel sportive? It is a little static; I think that we want to something trendy Association Grouping ideas, finding similarity/uniformity, difference/contrast, how people interact with the design artefact and how the design artefact interacts with the environment [START_REF] Finke | Creative Cognition-theory, Research, and Applications[END_REF] If I start by an iPod which has a hard angles to differentiate into two components, fine plastic and bright/clean colour, ...

Transformation

Ideas are shifted to make interesting and useful entities such as new value and analogy [START_REF] Finke | Creative Cognition-theory, Research, and Applications[END_REF] There is an automated vacuum cleaner, like a robot, which can move by itself Judgment/decision Make a judgment or evaluation on ideas according to the design brief, related to design information, or designer's satisfaction I like/dislike this form process; retrospective protocols may also cause insufficient and reinterpreted information due to the decay of LTM [START_REF] Bilda | The Impact of Working Memory Limitations on the Design Process During Conceptualization[END_REF][START_REF] Cross | Analysing Design Activity[END_REF][START_REF] Davices | Effects of Concurrent Verbalization on Design Problem Solving[END_REF][START_REF] Ericsson | Protocol Analysis: Verbal Reports as Data[END_REF][START_REF] Lloyd | Can Concurrent Verbalization Reveal Design Cognition?[END_REF].

More recently, Gero and Tang [START_REF] Gero | Differences Between Retrospective and Concurrent Protocols in Revealing the Process Oriented Aspects of the Design Process[END_REF] showed that concurrent and retrospective verbalisation protocols have very similar outcome in case of the process-oriented aspects of designing. However, the debate on the validity of think-aloud protocols is still ongoing.

Given the difficulties related to data collection, we used an activity-based approach, which represents a combination of these methods. Indeed, concurrent protocols are considered better suited to our study in that we focus on design information and related to cognitive operations. Semi-directive interviews [START_REF] Lindlof | Qualitative Communication Research Methods[END_REF] were also conducted at the end of the experiment to compensate for the deficiencies of the concurrent methodology.

Participants

We recruited two third-year undergraduate design students and six expert product designers (one female and seven males). The six expert designers had a mean of 9 years of experience. If one designer who had worked in product design for 28 years is excluded, the mean number of years of professional experience decreases to 5.2 years.

Procedure and equipment

The experiment was conducted at the design agencies of the participants to collect data in their natural working environments. As shown in Fig. 4, we used two video cameras and one voice recorder to collect verbalisations. One video camera captured the movements of the hands of each designer and recorded close-ups of the sketches, and the second recorded the entire body of the designer.

The protocol involved three phases:

(1) Warm-up phase, in which we explained the procedure of the experiment and participants became accustomed to the practice of concurrent verbalisation ($15 min). (2) Concurrent verbalisation, in which participants were asked to work on the design brief: Designing a Nike vacuum cleaner.

During this phase, they started to generate early sketches using traditional tools and simultaneously verbalised their thoughts ($60 min). (3) Semi-directive interview about the mental images, semantic descriptors, and forms generated as well as about the relationships among those three types of data ($15 min).

Analysis: coding

Using the principles of protocol analysis recommended by Suwa and Tversky [START_REF] Suwa | What Do Architects and Students Perceive in Their Design Sketches? A Protocol Analysis[END_REF] and Gero and McNeill [START_REF] Gero | An Approach to the Analysis of Design Protocols[END_REF], the entire verbal protocols were transcribed and segmented for coding according to our dual coding scheme (Table 1). Next, written transcripts were attached to corresponding video clips. The video analysis software INTERACT [START_REF]Mangold Software and Consulting GmbH[END_REF] was used to reduce the time involved in this process and to produce reliable quantitative results. The coding process [ ( F i g . _ 3 ) T D $ F I G ] Fig. 3. Information processing model (integration of the multiple components of working memory).

[ ( F i g . _ 4 ) T D $ F I G ]

Fig. 4. Design of protocol study.

used the Delphi method [START_REF] Gero | An Approach to the Analysis of Design Protocols[END_REF] involving two coders. The reliability of the coding process was measured by calculating the percentages of inter-coder agreement. This figure was higher than 82%, which indicated that the coding process was reliable. Videotaped sketches were also used to complete and verify verbalised content. Our coding scheme, presented in Table 1, includes two categories: design information and cognitive operations. As noted above, the coding scheme for design information was based primarily on our previous work on Kansei words [START_REF] Bouchard | Kansei Information Processing in Design, IASDR Conference[END_REF]. The level of an item of information can be understood in terms of its position on an axis from abstract (high-level information) to concrete (low-level information). The scheme includes 10 categories of design information. The coding scheme for cognitive operations was based on our descriptive model presented in Section 2.3. This framework includes stimuli, perceptual action, questioning*, association*, transformation*, and judgment/decision and is based primarily on the Geneplore Model [START_REF] Finke | Creative Cognition-theory, Research, and Applications[END_REF] (the cognitive operations marked with asterisks, which are related to the process whereby information is retrieved from long-term memory and stored in short-term memory, are of particular interest). The complete coding scheme enables understanding of connections between mental representation during retrieval and external information during sketching and also yields an encompassing depiction of the cognitive processes involved in categorising design information.

Note that we coded ''silence'', which is not a cognitive operation, when designers did not verbalise their thoughts and remained silent. We did so because we believe that this code facilitates the anticipation of certain internal cognitive processes that are rarely verbalised but that may enrich our model. In addition, responses consisting of replicas of a given design brief, expressions of needs/difficulties, jokes, etc. were coded as ''other'' and set aside for further study (the percentage of the ''other'' response was negligible compared with those of other responses).

Results and discussion

In this section, based on the video and audio protocols, we intended to identify the kind of cognitive operations that extract design information from memory and to determine how this design information is transformed or categorised during early sketching. We subsequently applied our dual coding scheme including design information and cognitive operations (Table 1). Finally, both quantitative and qualitative approaches were integrated to produce a cognitive model depicting the mental categorisation of design information processing performed by designers in Section 5.

What types of design information were verbalised during early sketching?

The substance of the comments made by the designers was very dependent on the design brief: Designing a Nike vacuum cleaner. For example, representative words in value categories included 'dynamism' and 'aesthetics', and the most common semantic descriptors included sporty, dynamic, fluid, classic, technical, fun, friendly, etc. The designers also employed 12 analogical words referring to, for example, sports (using a harness or scooter, lifting weights, using flippers, cycling, dancing, etc.), biomorphism (animals: shark fin, humans: mouth, and vegetables), and shoes and luggage (backpacks, accessories, etc.). These references draw heavily on semantic and conceptual associations with the Nike brand (e.g., shoes for sports). Other sectors (e.g., industrial products, household electrical appliances used for protection and air conditioning, robots, containers, and real estate) were also mentioned. The category encompassing the function of the target product consisted of responses related to its internal mechanics, units, and uses and operations such as ''fan'', ''dust bag'', ''air cushion'', etc.

Consistent with the quantitative results of a study on design information reported by Kim et al. [START_REF] Kim | A Study on Designer's Mental Process of Information Categorization in the Early Stages of Design[END_REF], high-level information was used most frequently (47.7%), followed by middle-level (36.7%) and low-level (15.6%) information. Thus, high-and mid-level information accounted for 84.39% of the words verbalised during early sketching. Low-level information tended to be represented in sketches rather than verbalised. The detailed frequencies of each category are presented in Fig. 5. The most frequently verbalised content was related to function (27.6%); this was followed by semantic descriptors (21.2%). The remaining six categories were mentioned relatively less frequently.

Cognitive operations during the categorisation of information

Fig. 6 shows the frequencies for different cognitive operations. On average, association accounted for 44.9% of all cognitive operations, judgment/decision accounted for 18.0%, perceptual action accounted for 12.9%, transformation accounted for 12.1%, questioning accounted for 9.7%, and stimuli accounted for 2.4%. During the earliest generative phase, designers exerted relatively more effort to generate ideas by retrieving design information from memory; retrieval processes of all sorts (association/transformation/questioning) accounted for 66.7% of all cognitive operations. Thus, judgment was used less frequently than association. In addition, stimuli rarely inspired responses; because our study focussed on memory-driven processes, we tried to eliminate external stimulation and encouraged designers to rely solely on their mind/memory during the task.

Moreover, because the cognitive operations related to retrieval processes were of great interest, we intend to recode association and transformation responses in terms of the subcategories of design information (cited in Table 1). According to the three levels of information, design information can be associated in three ways: descending association (from concrete to abstract), ascending association (from abstract to concrete), or same-level association.A more detailed analysis of the results showed that a plurality of the 44.9% of the responses accounted for by association was samelevel associations (22.2%), i.e., links between functions (Mf-Mf), semantic descriptors (Hs-Hs), or sectors (Ms-Ms); this was followed by ascending associations (12.0%) and descending associations (10.7%). Fig. 7a shows the frequencies of each subcategory of association. Most ascending associations involved the middle to the high level (M ! H), referring to links between functions and semantic descriptors (Mf-Hs); or the low to high level (L ! H), referring to links between descriptions of forms and semantic descriptors (Lf-Hs). Representative descending associations included the link between functions and descriptions of forms (Mf-Lf) or the use of words to form descriptions (Hs-Lf). Using the cognitive operation of transformation, designers created new and interesting ideas or concepts by forming analogies with functions (Mf-Ha, 43.8%) or by exploiting the meanings of words (Lf-Ha, 36.3%) (see Fig. 7b). In Section 5, the links between association and transformation will be discussed in greater depth and presented as a cognitive model for the mental categorisation of information.

Changes in cognitive operations over time

To compare changes in the six cognitive operations over time, we summed the number of cognitive operations in each 10-min interval. The normalised frequencies of cognitive operations were calculated as follows: (normalised A =(A À mean)/standard deviation) [START_REF] Bilda | The Impact of Working Memory Limitations on the Design Process During Conceptualization[END_REF]. Thus, if a cognitive operation increases in frequency, the normalised will have a positive value, and if the cognitive operation decreases in frequency, the normalised frequency will have a negative value (Fig. 8).

We observed two different groups of cognitive operations that shared a similar tendency. One group consisted of association, transformation, questioning, and stimuli, and the other group consisted of perpetual action and judgment/decision. During the first 40 min, the only negative variance was observed for perceptual action during the first 10 min; this may be attributable to the tendency of designers to rely more heavily on memories for categorised mental information at the beginning of the design process. After a brief interval, the designers started to generate early sketches to represent their ideas and/or identify errors. For this reason, the operation of judgment/decision resembles that of perceptual action. During the remainder of the observation, all variances tended toward negative, indicating that the designers' [ ( F i g . _ 6 ) T D $ F I G ] cognitive operations slowed after 40 min. However the variance was higher for perceptual action than for the other cognitive operations; that is, designers continued to improve their ideas by sketching or retouching the features of forms until they were satisfied with the outcomes.

Limitations of the current methodology

One might question whether a designer's mental processes can be inferred from concurrent verbalisation and/or whether sketching may be inhibited by the pressure of thinking aloud. In our specific study, designers verbalised their thoughts during 81.9% of the session and remained silent for 18.1%. During more than half of the time (57.1%), designers simultaneously verbalised and generated sketches; designers sketched without verbalising during only 9.3% of the session. Additionally, a pilot test showed no significant differences in the production of sketches during concurrent verbalisation and during silence.

However, as Coley et al. [START_REF] Coley | An Introduction to Capturing and Understanding the Cognitive Behaviour of Design Engineers[END_REF] reported, the think-aloud method may result in interference. For example, some thoughts cannot be verbalised without causing a distortion in thinking. In addition, we assumed that inter-individual differences due to age, sex, and working experience (novice, expert) occurred. Moreover, as our participants were all French and worked in the same design agency, cultural and status differences may not have been taken into account; indeed, analysis of these variables may prove interesting with a larger panel of designers.

Cognitive model of the mental categorisation of design information processing performed by designers

In this section, we present a cognitive model of the mental categorisation of design information processing performed by designers. This model is focussed specifically on the structure of design information and two cognitive operations, association and transformation, which are representative of the cognitive operations related to long-term and working memory. These provide clues to help us identify how designers encode and store information in long-term memory.

As Fig. 9 illustrates, the solid lines represent the direction of association, and the dotted lines represent the direction of transformation. The width of the line indicates the frequency with which cognitive operations were performed on design information. The structure of design information is represented in the red boxes. The size of boxes reflects the frequencies of particular types of as percentages of all verbal responses on the protocol.

The predominant forms of design information involved functions, semantic descriptors, analogies, and descriptions of forms. Designers tended to use same-level associations among elements of design information (horizontal), especially between functions, pieces of semantic descriptors, functions and sectors, and sectors and their contexts. Some excerpts from the verbalisations are given as follows:

''I'll try a backpack type of vacuum cleaners. This model should provide enough power, but it should not be too heavy to carry on his shoulder. Also, I would guess that a potable battery-powered model will still be a problem. It is due that a wrong position of air evacuation could cause a person to heat up''; or ''I would like to start with an automatic vacuum cleaner, ah yes, like a robot, which has a technical aspect, like 'hi-tech'; and has a look more masculine, seductive, and aerodynamic''.

Remarkably, designers also tended to associate information across different levels (vertical) including between functions and descriptions of forms functions and semantic descriptors, and semantic descriptors and descriptions of forms (and vice versa).

Here are a few excerpts from the verbalisation: ''Nike vacuunm cleaner, Nike makes me imagine a form like a Capricornus'sh o r n which might be more rounded...''; or ''regarding colour ranges, sport colours in my head are very flashy, vivid, and dynamic. So I could use primary colours: red, green, blue, or yellow with a black accessory; and it could be better if I use glossy materials such as plastics, metal''.

This model also confirmed that designers tend to associate design information according to rules that span different levels of information and relate colours, textures, and shapes. In addition to transformation, high-level descriptors (values, semantic descriptors, etc.) may serve as sources of creativity in designing insofar as these descriptors reflect the designers' personal sensibilities and tendency to create designs based on divergent ideas. Thus, the bidirectional associative links between high-and low-level information constitute very interesting foci for research on the generative phase of designers' work.

Conclusions

In this paper, we explored how designers mentally categorise design information during early sketching performed in the generative phase of the creative process. Our research question was what kind of the mental information is extracted and how this can be transformed or categorised during early sketching. By employing action research approach, we initially proposed a descriptive model of information processing involving memory theories drawn from cognitive psychology. To enrich and validate this model, we then used a think-aloud method to conduct a protocol study with product designers. We subsequently applied our dual coding scheme, derived from video and audio protocols, to identify deign information and cognitive operations relevant to this specific phase. Finally, both qualitative and quantitative approaches were integrated to produce a rich cognitive model of the mental categorisation of design information (see Fig. 9).

Three types of results (qualitative, quantitative, and integrated) showed: (1) two representative cognitive operations, association and transformation, were particularly related to retrieval processes of mental information. The finding explains a cognitive mechanism about how mental information is encoded and stored in long-term memory (LTM) and moved to working/short-term memory (WM/STM) during the early sketching in the generative phase. In addition, we have confirmed a strong correlation between the perception and the judgment/decision and (2) regarding a structure for design information, functional and structural analogies as well as links among functions, semantic descriptors, and descriptions of forms have emerged as an area of great interest. Particularly, a significant use of high-level information (semantic descriptors and analogy) would be interesting to investigate because it could influence the creativity and emotional aspect of design.

Therefore, we need to introduce additional coding schemes related to the emotional aspects of perceptual and generative processes to refine and enrich our cognitive model. In addition, we plan to validate our cognitive model with a large panel of designers and compare the possible differences between the novice and expert designers in the rate of cognitive operations and a structure of design information. Furthermore, given that the notion of information level was initially derived from the field of artificial intelligence, where it is used to develop specific algorithms, the findings suggest that our model may be helpful in developing a list of specifications for the design and development of computational tools. The development of design specification is under way; it involves a construction of database (semantic descriptors, archetypes, divers analogy issues from different sectors), an association between design information, transformation of forms (morphing in terms of semantic descriptors, or analogy), a support of the memorising process of design precedent, etc.

Fig. 1 .

 1 Fig. 1. Research methodology: action research approach.

Fig. 5 .

 5 Fig. 5. Frequencies of types of design information.

Fig. 6 .Fig. 7 .

 67 Fig. 6. Frequencies of cognitive operations.

Fig. 8 .Fig. 9 .

 89 Fig. 8. Normalised frequencies of each cognitive operation every 10 min.

Table 1

 1 Protocol coding scheme (based on verbal protocol).

	Coding (code)	Description	Examples
	Design information [10,30]
	High level (H)
	Values (Hv)	These words represent final or behavioral values	Security, well-being
	Semantic descriptor (Hs)	Adjectives related to colour, form, or texture, but also impressive	Playful, romantic, aggressive
		words in the field of Kansei Engineering
	Analogy (Ha)	Objects in other sectors with features to integrate in	Rabbit ! speed
		the reference sector
	Style (Hy)	Characterisation of all levels together through a specific style	Edge design, classic
	Middle level (M)
	Sector name (Ms)	Object names describing one sector or sub sector being	Sports
		representative for expressing a particular trend
	Context (Mc)	User social context	Leisure with family
	Function (Mf)	Function, usage, component, operation	Modularity
	Low level (L)
	Colour (Lc)	Chromatic properties using qualitative or quantitative	Yellow, light blue
	Form (Lf)	Overall shape or component shape, size	Square, wavy
	Texture (Lt)	Patterns (abstract or figurative) and texture	Plastic, metallic
	Cognitive operations
	Stimuli
	Selectively concentrating on one aspect of
	outer/inner senses [42]

Acknowledgments

This study refers to GENIUS project (http://genius-anr.org), funded by the ANR (AGENCE NATIONALE DE LA RECHERCHE) and runs from 2008 to 2011. The authors wish to thank the designers from Diedre Design agency and other designers who participated in our experiment, and specially thank for Laurence Moscardini, laboratory of Cognition Humaine & ARTificielle (CHArt), University Paris 8.


Heon Song
email: heon.song@paris.ensam.fr

Carole Bouchard

Robert Duchamp

Modeling the early stages of a user-centered process in architectural design adaptation of the methodologies Product Design

Keywords: architectura/ design, user centered design, NewProduct Design

ln order to reach a degree of quality in architectural buildings thati s like/y to / ead to user safisfaction, archi tectura/ design relies on integrating user-re/ated information even before the generafion of building concepts. However, integrating such informafion may be seen as a hindrance to architectura/ creation. lt therefore seems necessary to propose a methodo/ogica/ approac h that al/o'AS integration of a user-centered point of view as v.e/I as generation of creafive architectura/ concepts. Our research proposes to app/y a co//aborafive process of New Product Design (NPD) in order to enrich the more tradifional process of architectural design. We v.ill present some experiroental oork carried out as part of an archi tectural project for the design of eroergency she/ ters, as an alternafive to rrore usua/ habitats. We v.ill then di scuss the possibi/ity of adapting NPD methodo/ogy to architectural design, and v.hat potential this offers to improv e the integration of user-related information v.ithin architectural creativity.

Introduction

Architects formulate problems and search for solutions based on data provided by a Project lnitiator [START_REF] Prost | Conception architecturale[END_REF]. Spatial organization takes shape as a response to this project , based on complex co-evolutions of problems and solutions (Dorst & Cross, 2001). ln the standard, traditional approach to architectural design, although taking the user into account is acknowledged as an essential parameter of solution-finding , this is often viewed as a constraining element , or even a hindrance to freedom in architectural creation (Pinson, 1993). Nonetheless , performance in any architectural project should be evaluated, not jus t based upon the architectural qual i ties of a formai abject, but also on the degree to which users appropriate this abject for themselves (Prost, 2002) ln order for design results to be optimal with respect to users, architectural design needs to define a methodology allowing integration of user-related information from the early stages of the process, in order to achieve true improvements in the quality of the end architecture (Quanjel et al, 2006).

2.A method for human-centered architectural design

Before presenting the stance chosen for this research, we will start by briefly investigating i l s historical context, namely how the methodology of architectural design came to evolve in past years.

2.1Pratiques architectura/es centrées uti/isate ur

ln the early 20th century, the concept of "usefulness" constituted a central tapie of architectural design. lnitially, users were considered in terms of their functional requirements. Users' expectations and their dreams were interpre ted through architectural practice. However, since architectural proposais proved ill-adapted to users, it became necessary to take users into account in a scientific and objective manner. New approaches were put forth to integrate relevant user-related information by making users participate directly to the design process. ln the 1960s, two kinds of user-centered architectural practices were prevalent . One was based on the direct participation of users to the design process , and another on the participation of human factors experts to architectural design. Following this evolution, userrelated criteria were increasingly recognized as. important design parameters [START_REF] Lawrence | Trends in architectural design methods -the liability of public participation[END_REF] . From the second part of the twentieth century onwards, consciousness of taking users into account in architectural design has been driven forward by social demand regarding the design of workspaces. Research on the ergonomie perception of such projects, as well as on the process of ergonomie intervention, was applied to architectural design. However , usercentered recommenda tions proved to be formulated either "too early" or ' 1oo late" (Bouché, 2001). If the intervention takes place when the project is already given concrete expression, relevant suggestions cannaibe integrated. Conversely, even if rigorous and accurate userrelated information are provided in the early stages of the project, these are often viewed as just another constraint limiting the architect's imagination. ln order to reduce the distance between concrete realization of the architectural abject and integration of needs and expectations expressed by users, architectural design relies on explicit and direct participation of users to the process. As Godschalk (O. Godschalk , 1970) points out , one key factor of participatory design is interaction between users, who provide information regarding their own behavior, and designers , who provide informati on regarding potential solutions. As Hill (J. Hill, 2004) also points oui, formulating the user' s point of view in a creative fashion may help increase , not diminish, the architect's competence. Interactions between architects and users are still a major tapie of research on participatory architectural design. ln verifying the creative potential brought on by participatory architectural design, Lawrence (R.J. [START_REF] Lawrence | Trends in architectural design methods -the liability of public participation[END_REF] highlights the need for a more effective methodological representation to assis!communica tion between designers and users involved in a participatory design project. Wulz (F. Wul z, 1986) poses the ques tion of how users might be more involved in the design process, and shows the need I o democratize architectural design in order to alleviate the dominance of architects' influence over the project, since architects then reject user proposais.

Prog-amming user centered architectura/ design

Since the 1960s, much research has been carried out into how one should manage and develop processes of architectural design (Baudon, 2004). One such example is the work of Alexander (Ch. Alexander , 1964) who analyzed the architect's as a problem solvi ng activity . lndeed, architectural design may be viewed as the search for a program responding to the design problem, i.e. a description and prescription that are most adequate to the context of the project . To achieve this, Alexander stresses the needI o include and involve future users.

According to him, the raie of the architect is to allow spatial design to conform to users' persona! aspirations. According I o this view, he proposed a rational method translating the unconscious process of architectural design into an conscious one (Martin, 2000 ;Baudon, 2004). But this idea, which supposes that the problem may be fully defined before elaborating the solution, led to much criticism. Alexander's proposed approach implies that the architectural abject is but the product of a hierarchical , functional logic, as might be a product design through engineering (Conan, 1990). ln the 1990s, based on the premise that architectural design had been rationalized according to the same principles as those guiding industria design, Michel Conan, a French architect, proposed a model of the main stages of architectural design. He viewed architectural design as a creative problem-solving activity, integrating research results from the social as well as technical sciences. He then proposed a method for architectural programming. The dominant idea in this method is that architectural intent is no!jus!the result of problem solving,but also involves the architect following a path allowing progressive adjus tment of use-related intentions with technical and architectural possibilities.

The current state of the user centered process of architectural design

Zwemmer defined a process of user centered architectural design. He describes this process as an interaction between the architect and a group of users. Kernohan (cited by Zwemmer) views taking users into account as a factor of increased complexi ty in the process of architectural design. ln order to contribute to improved integration of user-related information, our research proposes an analysis of the initial stages of the design process, i.e. those stages where design concepts are generated. High perrformance in this stage is essential I o the quality of end products of design (Rickaby, 1979;[START_REF] Fruchter | lnterdisciplinary communication medium for collaborative conceptual building design[END_REF][START_REF] Austin | Mapping the conceptual design activity of interdisciplinary teams[END_REF]Quanjel, 2006) .

The NPD model : collaborative user centered design

ln order to help designers integrate informa tion related to users, as well as generate creative architectural concepts in the early stages of desigrn, we put forth our main hypothesis , namely that a generic model of New Product Design (NPD) may be used in architectural design. The collaborative approach derived from NPD methodologies should make it easier to integrate user-related informati on in the early stages of architectural design. User needs analysis : based on the results of prior s!udies, participants sugges! ideas which are mas!sui!ed to project goals , using group imaginati on;

x ldea generation: the goal of this stage is to carry out a creative activi ty during which participants, who are not experts in the field of architecture but are potential "end users", get to grips with project data, i.e. its context and goal. Participants to l hese creativity sessions note thei r ideas in the form of cards describing and illustrating their principle in a synthetic fashion , as well as their main advantages and drawbacks;

x Concept generation : This stage, carrüed out by the architect and design team, involves linking, categorizing, combining, and synthesizing patchy ideas into concepts by providing ! hem with a common tille. Description of these concepts is then carried out in more depl h within a second stage. This in-depth explora tion requires expert knowledge. Criticism regarding technical and economical feasibility of these concepts may also be addressed at this time.

x Concept selecti on: ln order to evaluate basic concepts from a user-cenl ered point of vi ew, a document is handed out to project participants, generally a questionnaire followed by an evaluation grid. Usability inspection methods may be applied to these concepts in 1ater stages of detai1ed design. We have chosen to apply the NPD model to architectural design following the collaborative approach promo! ed by recent work on the design of innovaîive products. The area which we chose to explore as a field of applica tion wa s the design of an emergenc y shelter. We have chosen a NPD methodology that highlighting collaborati on between professionals from 0 various fields of design. These design actors are experts in the field of ergonomies. This process also provides means to analyze designer actions and results thereof , in the form of i ntermediate representations of an emergency shelter.

An experimental application of the

An architectura/ project : emergency shelter

The emergency shelter seemed an interesting tapie for us I o test the pol ential of adapting product design methodologies, which are collabora tive by definition,I o architectural design. lndeed, such housing serves as a replacement for existi ng habitat in the event of i ts destructi on by natural or man-made disasters. ln such projects, i li s essenti al I o account for several unavoidable constraints as well as funàamental needs, which may prove of vital i mportance in this very specific context. Designing an emergency shelter , even a small one, relies on a fund of knowledge from various fields , knowledge which must be combined and structured as part of a mel hodology aiming to assis! collaborative creativily. Il therefore seems a particularly relevant applica tion to validate a design approach wrth a strong focus on user needs , but also on the design teams ability o generate new and ingenious ideas given the various constraints included in the project. Therefore, this field of application i s particularly suited to validating a design model inspired by NPD and applied in the field of architecture.

A description of the experimental process

We carried out a collaborative project in architectural design following a modified version of the generic model described in part 3.2 (fig. 3). ln this part, we describe activities and behaviors of al1 project participants at each stage of the process.

The design project

Figure 3. Génération des i dées

Following a brief presentation of the results of user needs analysis , the design team parti cipated i n a creativily session in order to generate a number of creative i deas. Ei ghl participants were present, each wrth their own professional background (architects, engineering designers , ergonomists, and designers). As is frequently recommended in creativi ty sessions, critical reactions to the results, whether based on knowledge or persona! opinion, were forbidden. Following this strict rule , a number of techniques presenl ed below were chosen and applied to s!imulate i dea generation. Through these, collective unders tanding of the project arase based on free-minded and iterati ve communication between participants, giving much importance to the imaginati on. At the end of this session, parti cipants were asked to produce a number of idea-cards, i n which hand-drawn sketches complemented verbal descriptions of ideas, highlighting the principle, advantages and drawbacks of each. Session duration was 3 hours , during which about 30 cards were produced.

Creativity techniques used during the session were as follows:

-The purge: before anything, participants did away with all preconceived i deas regarding the product to be designed , by writing ! hem down and presenting ! hem orally. This initial exchange , based on spontaneously generated images and words, allows to star!off creative interactions in a very natural way:

-Scenarios: the problem is contex tualized, based on a series of ideal , or conversely, catastrophic situati ons, i n order I o let parti cipants' attitudes to the problem emerge spontaneously, and let !hem imagine so utions wi th a concrete backing. Scenarios may be acted out using improvisational raie-play.

• Analogical reasoning: participants suggest ideas by seeking !hem out i n fields remote from the initial problem domain. This allows them to open up a field of possibili ties and let the imagination take over ln order to circumven!the problem. ln order to search for soluti on ideas, we relied on fields that had no connecti on wih an architectural product such as the emergency shetter. Such fields i ncluded plants, animais , sport, etc.

Within this projecî for the design of an emergency shelter, designers had to account for the extreme condi ti ons of temporary housing. Participants were divided into two groups. Each of them listed and described potential difficul ties, imagining situations where lhey might occur and suggesting potenti al solutions. Scenario-based design allowed participants to projec! themselves as users in si tuations involving an emergency shel ter.

Generation and implementation of concepts

0 ldea @ Pre Concept lndepth pre concept

Figure 4. Génération des concepts

The concept definition stage starts off with the generation of preliminary concepts by small groups of 3-4 designers , each including an . architect and other design professionals (designers, engineers or ergonomists). These smaller groups were put in charge of identifying tapies responding strongly to the project in order to group the ideas produced in consistent subgroups, illustrating more global concepts that might be used to design the end product. New ideas may be generated in thi s stage in order to connecl existing i deas,I o strengl hen an existing concept, to make a set of ideas more consistent or comprehensive to turn ilinto a concept . ln order to better carry out this complex activi!y, ideas produced in the prior stage are categorized according to common wordings. They are then put togel her for examination of their mutual compatibility, to construct groups of ideas. ln order to make these groups more apparent and to enrich them, complementary ideas are generated and added to them.

Participants from these small groups thus generated preliminary concepts, i.e. consistent sets of ideas , based on about 30 initial ideas. At that time, the architect, as session pilot, asked groups I o look for product concepts in a more global and creative view , wi l h the explicit goal to make each preliminary concept more consistent. This deep conceptual exploration, carried out in a dynamic and collaborative way , allowed participants no!just to link ideas together, but also to initial e specific patterns of reasoning based on cognitive transformations. lndeed, the pilot architect stressed the importance of the need for complementarity between ideas in order I o genera te preliminary concepts.

ldeas generated in the ini tial stages tended to offer real-world solutions to l ocal or parti al problems, rather than global responses to project goals. The l ask of l rying to establish connections and giving each group of loosely-knitted ideas a specific identity within a short timeframe turned out to be very difficult. Creativity based on preliminary concepts was an approach spontaneousl y chosen by participants, 1hrough which 8 preliminar y concepts were quickly defined on the basis of ideas generated beforehand and of roughly ten new ideas. This stage relied on idea search within more specific domains, and on deeper conceptual exploration. To achieve this, we invited more specialized participants: a construction engineer, a materials engineer , an aeronautics engineer, an ergonomist , two designers and two architects. lvlore information was provided to ! hem regarding the context of the project in order to l ocus creativity on more specific points.

The first part of this session consisted in finding new ideas regarding design choices and principles that had not been defined with sufficient precision beforehand. Participants then produced idea cards. The first batch of concep ts was then presented I o the participants, allowing generation of new ideas or concepts. Thus, the 8 concepts generated in the prior stage were completed with around 20 new ideas . and 3 new concepts. The ideas focused on specific project elements were eventually integrated to the various existing groups through critical discussion confronting the points of view of the various design professionals involved. This discussion allowed crossfire of knowledge, opinions , and more importantly, types of expertise to give rise to inspiration for the generation of new concepts.

The usual view of this is that the raie of domain experts and specialists expresses itself in an analytical approach aiming to correct a real-world, physical artefact. Wha t we have shown here is that communication between experts of various fields might bring forth some degree of creativity, as long as participants are involved in a leisurely, fictitious and convivial situation, which leads participants to show a great degree of tolerance despite obvious differences in their respective points of view. When participants were asked to link their ideas to an existing idea set , they had to analyze and interpret these various sources of informa tion, all the while explicating the reasons for their choices. Data based on local and very specific knowledge turned out to be a major source of creative inspiration to the subgroups of participants.

Al though the initial stages of the design project are concerned wi l h free-minded involvement of domain novices in order to generate numerous concepts, the next stage requires examining the feasibili ty of these concepts in order to reach consensus between the points of view of the various experts involved. At this point, the design team will share concepts, ending up with merging some of them, and elaborating upon others. Concepts developed i n l his way are presented in the form of a concept card, formalized in equal detail , before these can be evaluated. Concept cards are based on sketches which allow the subs tance of a solution to be clarified i n wriling.

Representations of concepts must include a simple, clear and global explanal ion before going into any detail. lndeed, if the description is tao refined from the star!, this may prevent evaluators from interpreting the concept and analyzing il clearly. An easy-10-grasp presentati on of concepts ranging from global to detailed levels, presenting each concept at various resolutions, will help designers gain a better understanding of each one. To combine results of the intermediate evaluation of concepts with project developments, the questi onnaire seems an appropriate tool I o allow decision making i n design as we ll as providing a more concrete response I o project demands.

Concepts were presented i n the form of concept cards and submitted them to the judgemen t of members from the design team (10 persans in total), using a ques tionnaire and an evaluation grid as methodological tools for evaluattion. Based on this, participants were asked to l hink spontaneously about the concep t they preferred overall, as well as I o classify evaluation criteria and complete the lislwith specific criteria. The goal of the evalual i on grid was I o allow designers to reflect in more depth about the various parameters involved, grading each concept according to the criteria described i n the scope statement . Grading was then weighed based on the criteria participants viewed as most fundamental. This process allowed us to assign an average grade to each concept, ! hereby helping wi h concept selection. Two evaluation stages were carried out i n a democrati c fashion, allowing us I o select those products that had received top grades in each criterion.

Discussion

One major stake of our research has been to .analyze how I o assis!the generation and developmen!of architectural concepts, integrating user-related data in the ini tial stages of the design process. ln order to propose an application scheme for the generic collaborative methodology of NPD in the early stages of architectural design, we will discuss i n this part the behaviour of the members of the design team, as well as the results obtained in the course of this architectural projecl.

Collaborative creativity in architectural design

ln traditional architectural design, the archi l ect initial es and shapes his project by priori l izing constraints and elements defined from the time of the initial project order. From this diagnosis , formulated ! rom a persona! point of view, he searches for and elaborates architectural concepts. ln developing sketches to help ease simulation of future use and coordination of design choices , he verifies and contrais his architectural reasoning. Our methodology, however, proposes an alternati ve based on collective work involving several disciplines.

From a creativity-based point of view, and compared with the architect's more traditional individual working practices, we can see a number of advantages. ln the needs analysis and idea general ion stages , crossing various the contributions of participants allows rapid genera tion of large quantities of ideas. The next stage of in-depth concept elaboration !hen allows enriching concepts with further ideas, based on the specific , expert knowledge of participants involved.

Al though we have shown it is possible I o gather a design team wi thin a collective, creative activity in architectural design, the question rema ins as I o how synthe!ic the ideas produced should be I o be project-relevant . ln order to enrich concepts generated through connecting existing ideas, expert participants sugges ted new ideas. Besides the architect , few project members seem interested in a synthetic view of things. They each proposed novel ideas , but these generally didn't complement each o! her.

lntegrating user-related information in the initial stages of architectura/ design

Amongs t the techniques used in our tirs!creativity session, the "scenario" tool allowed us to construct a common understanding of the project by playing the part of users. Participants thus highlighted a large number of problems and generated large numbers of solutions spontaneousl y and in a collective way.

During the second creativity session , which involved experts, the ergonomis t expressed his point of view regarding the user. This was a major contribution to enriching idea contents during concept elaboration. However, according to him, it was difficult to contri bute relevant and concrete ideas at this relatively abstract stage of the process. Despi! e this, we posit that his involvement in the early and abstract stage of concept generation may be seen as a potential opportunityI o integra! e user related infor mation in the design process.

Cofletive intermediate eva/uation

Whereas architects generally make persona! decisions when selecting a concept worth developing based on his professional experience , collective evaluation relies on the spontaneous opinions and perceptions of experts from various professions. This stage appears essential, no!just for choosing a concept ,but alsoI o interpret results of an evaluation. lndeed,such evaluations rely on information concerning needs and expectations put forward by potential future users. This type of i nformation should be integrated as early as possible in the design process in order to be applied to an architectural solution. Varying, or even opposite opinions between evaluators should be viewed as viable resources for user centered architectural design.

Conclusion

Contrary to the traditional view of architectural design, in which the architect carries out a persona! inquiry, our research has attempted to insl il a collaborative activity in the process, characterized by creative communication between the architect and the remainder of the design team, including engineers, ergonomists and future users. We have elaborated and put forth a preliminary model of the collective process of architectural design, integrating the user's point of view, which is likely to bring relevant resources to the creative activities involved in the early stages of design.

Through simulation, we applied an alternative model of architectural design in order to validate il. We believe that both the tacit knowledge of users (Spinuui, 2005) and collective intelligence in the design team (Fischer et al, 2005) may influence the quality of results in architectural design.

3. 1 AFi gure 1 .

 11 mode/ of architectural design based on mode/s of NPD Initial stage of the NPD process nouveaux For the pas! decade , research into the design of innovative products has focused on the concepts of novelty and utility . Scientists in the field have set the goal of elaborating and developing methodological tools to assist the onset of creati ve solutions in the process of concept generation. According to Quarante and Ulrich (fig.1), the initial stage of the NPD process is made up of four sub-s tages, ail focused on end-users: 1/ user needs analysis, 2/ concept genera tion, 3/ concept selection and 41 concept validation. Designers are provided wi th a scope statement, which defines produc!specifications. Followi ng this, a collecti ve search for ideas is carried out to generate a list of items li able to give rise to product concepts. Concepts are drafted, elaborated upon, and selected through a series o• f cycl es of divergence and convergence. At the end of this iterative process, a single concep t is selected and then developed.According I o NPD models , the design process starting with idea generati on up to concept selection may be structured as follows (fig.2The initial stage of architectural design based on a NPD approach x

  Figure 3. A model of the initial stages of user-centered architectural design

Figure 5 .

 5 Figure 5. Evaluation des concepts