Joël Vogt
email: joel.vogt@unifr.ch

Kris Luyten
email: kris.luyten@uhasselt.be

Jan Van Den Bergh
email: jan.vandenbergh@uhasselt.be

Karin Coninx
email: karin.coninx@uhasselt.be

Andreas Meier
email: andreas.meier@unifr.ch

Putting Dementia Into Context A Selective Literature Review of Assistive Applications for Users with Dementia and their Caregivers

Keywords: Dementia, Independent living, context-awareness, assistive applications

People with dementia face a decline of their cognitive functions, including memory impairment and difficulty to orient in time and space. Assistive applications can ease the effects of dementia by assuming and supporting impaired functions. Context-awareness is an accepted paradigm for assistive applications. It enables interactive systems to react appropriately to situations that occur during daily routines of people with dementia. However, there currently is no recommended framework to view symptoms of dementia in terms of context and context-awareness. The aim of this paper is to inform designers in the early design stages of assistive applications how requirements and needs of people with dementia can be represented in a context-aware application. Based on a systematic literature review, we elicit which context types are linked to the needs of people with dementia and their caregivers and how they are used in existing assistive applications in dementia care. Our focus is on applications evaluated and assessed with people with dementia. We also classify these assistive applications by the offered context-aware services. We observe that these should not be limited within the realm of the local residence; context types that are valuable in-house can, to a certain extent, also be leveraged outside a local residence. We believe the proposed framework is a tool for application builders and interface designers to accomplish an informed design of systems for people with dementia.

Introduction

Dementia affects about 4% of people over the age of 65 and 40% of people over 90. In Europe, at least half of the elderly population affected by dementia, have a mild form of dementia [START_REF] Mulvenna | Supporting people with dementia using pervasive healthcare technologies[END_REF]. The organization Alzheimer's Disease International estimates that the worldwide cost of dementia amounts to 1% of the global gross domestic product, or USD 604 billion [50].

Literature shows that the dementia syndrome itself does not thwart the use of digital assistive application, at least at its early stages [START_REF] Lauriks | Review of ICT-based services for identified unmet needs in people with dementia[END_REF][START_REF] Mileo | Support for context-aware monitoring in home healthcare[END_REF][START_REF] Robinson | Keeping In Touch Everyday (KITE) project: developing assistive technologies with people with dementia and their carers to promote independence[END_REF]. To what extent People with Dementia (PwDs) can benefit from assistive applications greatly depends on the ability to accommodate the user's cognitive impairments and other needs [START_REF] Lauriks | Review of ICT-based services for identified unmet needs in people with dementia[END_REF][START_REF] Monk | Simple, social, ethical and beautiful: requirements for uis in the home[END_REF][START_REF] Orpwood | Designing technology to support quality of life of people with dementia[END_REF][START_REF] Robinson | Keeping In Touch Everyday (KITE) project: developing assistive technologies with people with dementia and their carers to promote independence[END_REF]. This limits the use of standardized ICT applications [START_REF] Peterson | The phenomenological experience of dementia and user interface development[END_REF][START_REF] Lauriks | Review of ICT-based services for identified unmet needs in people with dementia[END_REF]. Moreover, assistive applications should be appealing to their users and not be perceived as stigmatizing [START_REF] Monk | Simple, social, ethical and beautiful: requirements for uis in the home[END_REF][START_REF] Robinson | Keeping In Touch Everyday (KITE) project: developing assistive technologies with people with dementia and their carers to promote independence[END_REF]. Hughes et al. [21] emphasize the importance to respect the dignity of PwDs. Context-aware computing allows the development of interactive systems that are aware of their users and behave accordingly [START_REF] Dey | Towards a better understanding of context and contextawareness[END_REF][START_REF] Dey | Designing mediation for context-aware applications[END_REF][START_REF] Gajos | Automatically generating personalized user interfaces with supple[END_REF][START_REF] Wobbrock | Ability-based design[END_REF]. The context-aware paradigm considers the users and the operating environment in the application design and behavior. Given the number of people with dementia and their desire for solutions to cope with dementia, building interactive systems tailored for this user group is extremely important.

Aims of the Paper

The aim of this paper is to provide a reference framework that assists the preliminary phase in the design and development of assistive applications for PwDs. Given the difficulties to evaluate this type of applications with the target audience, it is vital to maximize an informed design approach [START_REF] Astell | Involving older people with dementia and their carers in designing computer based support systems: some methodological considerations[END_REF][START_REF] Orpwood | Designing technology to support quality of life of people with dementia[END_REF]. We approached this by analyzing services of context-aware assistive applications in dementia care and how they exploit context. We also study the type of context that these applications use to address their users' needs.

Approach

We conducted a systematic literature review of projects that developed assistive applications for PwDs. The design and development of assistive applications for PwDs is a complex and error-prone task. While traditional user-centered techniques are suitable for abled-body people, Newell et al. [START_REF] Newell | User-sensitive inclusive design[END_REF] point out that they provide little guidance as to how to work with users with special needs. Traditional user-centered design encourages members of the design team to make their design choices from the user's perspective. However people with severe cognitive impairment are too diverse and their situation cannot be reflected as an average user. In addition a user group of people with disabilities has a greater variety of characteristics of functionality which may also be conflicting [START_REF] Newell | User-sensitive inclusive design[END_REF]. We therefore focused on projects which evaluated their running applications with PwDs. We further limited the scope to applications that react to context during runtime (in contrast to design time adaption to contexts of use). Additionally, we considered only literature we could access from our university network or library.

In a first step, we searched the bibliographical databases of ACM, IEEE, Sci-enceDirect and PubMed. The search query specified the following criteria for the abstract or title of literature: (dementia OR alzheimer) AND (context OR location OR activity OR ambient OR situation) AND (person OR people OR individual OR adult). ACM gave 10 results, IEEE 34, ScienceDirect 5, PubMed 1. In a second iteration, we removed candidates that did not evaluate and assess their technical solutions with PwDs. This clearly showed that very few of the research projects actually included user trials: ACM was left with 1 result [START_REF] Chang | A context aware handheld wayfinding system for individuals with cognitive impairments[END_REF], IEEE 0, ScienceDirect 1 [START_REF] Riley | An interactive tool to promote musical creativity in people with dementia[END_REF], PubMed 1 [START_REF] Robinson | Keeping In Touch Everyday (KITE) project: developing assistive technologies with people with dementia and their carers to promote independence[END_REF]. The number of publications on dementia and context that also performed evaluations with end-users are very low and does not provide sufficient material to define a design space for creating assistive applications. However, we used these papers as a starting point and elaborated on the respective projects they originated from. In a third iteration, we therefore searched references for projects that focused on assistive applications in dementia care. This led to 3 additional Research and development projects [START_REF] Donnelly | A mobile multimedia technology to aid those with alzheimer's disease[END_REF][START_REF] Lee | Lifelogging memory appliance for people with episodic memory impairment[END_REF][START_REF] Mulvenna | Designing & evaluating a cognitive prosthetic for people with mild dementia[END_REF].

The Person with Dementia as the User

This section puts a human face on dementia. It discusses the impact of dementia, in particular Alzheimer's disease (AD), on People with Dementia (PwDs) and their social context society in literature, to gain a sense of the complexity of this disease.

The Dementia Syndrome

Dementia is a syndrome of serious decline of cognitive abilities that exceed agerelated decline. Common symptoms are memory problems, difficulties to perform familiar tasks, impaired judgement, language deterioration, and mood changes. Dementia is a syndrome with different etiologies, of which AD is the most common type [START_REF] Association | 2012 alzheimer's disease facts and figures[END_REF][START_REF] Mandell | Alzheimer's Disease[END_REF]. Forgetfulness is generally seen as the primary symptom of dementia; however, this is not necessarily the case for every pathology. Usually, cognitive abilities irreversibly deteriorate over time and the underlying disease is incurable. There is not a single definition of dementia. However, they all do require a functional disability threshold that has to be crossed. Individuals can therefore exhibit a decline of cognitive functionalities that do meet the criteria for dementia [START_REF] Mandell | Alzheimer's Disease[END_REF]. Mandell and Green [START_REF] Mandell | Alzheimer's Disease[END_REF] describe dementia as "a syndrome of acquired persistent intellectual impairments characterized by deterioration in at least three of the following domains: memory, language, visuospatial skills, personality or behavior, and manipulation of acquired knowledge (including executive function)".

Alzheimer's disease

AD is a neurodegenerative disease and the most common form of dementia [START_REF] Association | 2012 alzheimer's disease facts and figures[END_REF]. Currently AD can neither be slowed down nor cured [START_REF] Association | 2012 alzheimer's disease facts and figures[END_REF]. Due to the complexity of AD, some even doubt whether a cure can ever be found [START_REF] Orpwood | Designing technology to support quality of life of people with dementia[END_REF]. AD is commonly diagnosed after the age of 65, although brain damage resulting from AD can start 10 to 20 years before first symptoms appear. The cause of AD is unknown. Memory problems that exceed age-related decline are early indicators. when the damage spreads to hippocampus. As AD advances, other impairments in other cognitive domains become apparent that curtails abilities to perform everyday tasks, language difficulties, difficulties to understand visual images and spatial relationships, confusion over time and space, misplacing and losing items, mood changes and social isolation [START_REF] Mandell | Alzheimer's Disease[END_REF].

Hodges [START_REF] Hodges | Alzheimer's centennial legacy: origins, landmarks and the current status of knowledge concerning cognitive aspects[END_REF] characterize the clinical process of AD as stages of patterns of impairment of the cognitive abilities memory, attention and executive abilities, language, visuospatial and perceptual and praxis . The first stage, mild cognitive impairment, is prior to the dementia onset. The worsening of cognitive abilities is characterized by the stages mild dementia, moderate dementia and severe dementia. While early on in the clinical process deterioration of abilities vary from individual to individual, the later developments follow similar patterns. However the duration of each stage differs from person to person.

Needs of People with Dementia

Dementia is often associated with forgetfulness and confusion. Temporal and memory impairment mean that PwDs need to be reminded of future and past activities and events [START_REF] Dröes | Dementia-related and other factors to be taken into account when developing ict support for people with dementia-lessons from field trials[END_REF][START_REF] Hawkey | Requirements gathering with alzheimer's patients and caregivers[END_REF]. Memory impairment also manifests itself as an increasing need for information about everyday issues. Hawkey et al. [START_REF] Hawkey | Requirements gathering with alzheimer's patients and caregivers[END_REF] cite an interviewee who wanted to know the role of the participating person (in this example a physician), the location of this person and the route, departure time, and what to wear. The authors also found that some participants had difficulties to relate with time or recognize people they know.

A cause for frustration was the increasing difficulty of some participants to use familiar devices and initiating or completing even simple tasks [START_REF] Dröes | Dementia-related and other factors to be taken into account when developing ict support for people with dementia-lessons from field trials[END_REF][START_REF] Hawkey | Requirements gathering with alzheimer's patients and caregivers[END_REF][START_REF] Wherton | Problems people with dementia have with kitchen tasks: The challenge for pervasive computing[END_REF]. Wherton and Monk [START_REF] Wherton | Problems people with dementia have with kitchen tasks: The challenge for pervasive computing[END_REF] analyzed the difficulties PwDs are faced with when performing Activities of Daily Living (ADL) and how they can be assisted. They found that the difficulties were resulting from sequencing problems, problems finding things, problems operating appliances and incoherence. Sequencing problems occur when incorrect objects or actions for a given step are used. This was seen as a result of being unable to control stimulation from objects or affordances that are not relevant for that task. The second cause for this problem is the degeneration of semantic memory. The impairment makes it harder for the Person with Dementia (PwD) to distinguish similar objects types. Episodic memory problems led to forgetting steps that were already taken; hence, repeating them. Omissions of sub-goals were also reported, when the sub-goal was too similar to the overall goal. The problem finding items was seen for one as a result of episodic memory loss. The PwD would not remember which places were already searched and repeat the search. The disability to identify visible items was also attributed to either not being able to subdue task-irrelevant stimulation or semantic memory impairment. The problem with using items was seen attributable to the inability to comprehend the use of an appliance. The participants did not know when to use an appliance or found it too difficult to understand its functionality. This is seen as a result of not being able to select between action schemas or the inability to remember the actions that need to be performed. Incoherence is seen as the problem when PwD engaged in activities that are not related to the overall goal.

Dementia aid is primarily situated within the residence of the PwDs, not on activities outdoors. Even though PwDs, at least at the early stages of their illness, appreciate outdoor activities [START_REF] Brittain | Ageing in place and technologies of place: the lived experience of people with dementia in changing social, physical and technological environments[END_REF]. However caregivers (CGs) fear for their love one's safety and are therefore reluctant to let their PwD leave their safe environment alone. PwDs may also be anxious about getting lost because they are uncertain about their location and finding their way home [START_REF] Brittain | Ageing in place and technologies of place: the lived experience of people with dementia in changing social, physical and technological environments[END_REF][START_REF] Dröes | Dementia-related and other factors to be taken into account when developing ict support for people with dementia-lessons from field trials[END_REF]. PwDs feel more conformable in familiar places. Brittain et al. [START_REF] Brittain | Ageing in place and technologies of place: the lived experience of people with dementia in changing social, physical and technological environments[END_REF] found that PwDs can use landmarks or ask other people to find their bearings. One interviewee would use photographs of older buildings to link the past memory with the current landscape. To reduce uncertainty about the PwD location, Wherton and Monk [START_REF] Wherton | Technological opportunities for supporting people with dementia who are living at home[END_REF] suggest to reinsure both parties by mutually sharing contextual information. Through mutual awareness, "the function of the technology becomes communication instead of monitoring" [START_REF] Wherton | Technological opportunities for supporting people with dementia who are living at home[END_REF].

Social interaction is vital for PwDs, e.g. [START_REF] Brittain | Ageing in place and technologies of place: the lived experience of people with dementia in changing social, physical and technological environments[END_REF][START_REF] Dröes | Dementia-related and other factors to be taken into account when developing ict support for people with dementia-lessons from field trials[END_REF][START_REF] Monk | Simple, social, ethical and beautiful: requirements for uis in the home[END_REF][START_REF] Wherton | Technological opportunities for supporting people with dementia who are living at home[END_REF]. However, the increased difficulty to manipulate items and problems impairment rises the bar for the PwD to interact with their social environment. Being more and more confined to their residence also affects social activities [START_REF] Brittain | Ageing in place and technologies of place: the lived experience of people with dementia in changing social, physical and technological environments[END_REF].

Challenges When Developing for Users with Dementia

Involving PwDs and their CGs in the design process requires empathy for the users and awareness of their abilities, needs and to their environment [START_REF] Aggarwal | People with dementia and their relatives: personal experiences of alzheimer's and of the provision of care[END_REF][START_REF] Monk | Simple, social, ethical and beautiful: requirements for uis in the home[END_REF][START_REF] Orpwood | Designing technology to support quality of life of people with dementia[END_REF]. CGs hold considerable sway over the PwD and need to be convinced of the project's merits [START_REF] Astell | Involving older people with dementia and their carers in designing computer based support systems: some methodological considerations[END_REF]. PwDs are in most cases older people who are affected by age related degeneration of physical abilities such as vision, hearing or tremor [START_REF] Hawkey | Requirements gathering with alzheimer's patients and caregivers[END_REF]. PwDs may be more or less aware of their conditions [START_REF] Hawkey | Requirements gathering with alzheimer's patients and caregivers[END_REF]. PwDs are also prone to emotional changes. They are easily irritated and may be insecure about their contribution or even be frustrated or anxious [START_REF] Mckeown | Actively involving people with dementia in qualitative research[END_REF][START_REF] Orpwood | Designing technology to support quality of life of people with dementia[END_REF].

It is therefore difficult for designers who have no previous contact with PwD to grasp the complexity of such users. Yet involving PwDs is imperative to gain an understanding of their very unique needs and requirements [START_REF] Davies | Prototyping cognitive prosthetics for people with dementia[END_REF][START_REF] Orpwood | Designing technology to support quality of life of people with dementia[END_REF][START_REF] Stalker | Eliciting user perspectives on what works[END_REF]. As Stalker et al. [START_REF] Stalker | Eliciting user perspectives on what works[END_REF] point out, if the PwD is the user, then "Reliance on carers for this information is foolhardy".

Novelty is often seen as problem for PwDs. Orpwood et al. [START_REF] Orpwood | Designing technology to support quality of life of people with dementia[END_REF] argue that "People with dementia will not be able to learn to use new devices in their home". Wherton et al. [START_REF] Wherton | Choosing the right knob[END_REF] offer a more nuanced perspective, suggesting that novelty itself is not the problem but rather "learning new arbitrary mappings and procedures". They found that direct implicit clues worked well to guide the PwD.

Context and Context-Awareness

Newell et al. [START_REF] Newell | Information technology for cognitive support[END_REF] suggest that user interface design for people with cognitive impairment should mitigate memory impairment, avoid cognitive overload and take into account individual characteristics. While to a certain degree these requirements are desired by all users, the reduced cognitive abilities of People with Dementia (PwDs) and the emotionally very demanding situation makes these rules imperative. Context-awareness is an accepted paradigm to adapt assistive applications to known contexts of use during design time and can adapt to a dynamic environment during runtime [START_REF] Gajos | Automatically generating personalized user interfaces with supple[END_REF][START_REF] Wobbrock | Ability-based design[END_REF].

This section presents the categories of context variables and context-aware behaviors for dementia care that were identified in literature. We use the definition of context and context-awareness as provided by Dey and Abowd [START_REF] Dey | Towards a better understanding of context and contextawareness[END_REF]. Their definition is as follows: "Context is any information that can be used to characterize the situation of an entity. An entity is a person, place, or object that is considered relevant to the interaction between a user and an application, including the user and applications themselves. [. . . ] A system is context-aware if it uses context to provide relevant information and/or services to the user, where relevancy depends on the users task.". This implies that context is a fairly broad concept. Their definition does however provide helpful cues to determine if a piece of information is context or not: It puts contextual information within the scope of the interaction between the user and the system and it does not limit context-aware behavior strictly to context that is obtained during runtime.

Dey and Abowd propose four primary context dimensions to describe the situation of a subject:

1. activity: the intrinsic properties that determine the state of an entity. E.g. feelings, tasks or status. 2. identity: the extrinsic properties that describe an entity independent of time and location. For example the name of a person, the phone number or personal relationships. 3. location: the location of an entity in a physical space. 4. time: the location of an entity in temporal space. Section 3.1 extends Dey and Abowd's categorization of context for assistive applications in dementia care. We studied the research and development projects identified in Sect. 1.2 and literature on the needs and requirements of discussed in Sect. 2.3 to elicit the second level context types that are relevant to provide services and information to PwDs and their caregivers (CGs). Literature on needs and requirements drew our interest to identify context types that have not yet been used in current applications. We also studied the runtime behavior of assistive applications for PwDs in literature that use context to provide relevant services and information to the user. Section 3.2 summarizes our findings as context-aware services.

Context Types for Dementia Care

This section discusses the context types that our literature review found represent dementia related deficits for assistive applications.

Activity. The activity context type describes the intrinsic properties of an entity [START_REF] Dey | Towards a better understanding of context and contextawareness[END_REF]. Dementia affects the ability of PwDs to perform activities and influences their emotions. Their abilities and emotional state influence the dialog between a Person with Dementia (PwD) and the assistive application. Activity also describes the capabilities and state of devices. The following context types were found:

-Emotion: Dementia influences a person's emotions and their ability to control emotions [START_REF] Brittain | Ageing in place and technologies of place: the lived experience of people with dementia in changing social, physical and technological environments[END_REF] and anxiety [START_REF] Hawkey | Requirements gathering with alzheimer's patients and caregivers[END_REF][START_REF] Brittain | Ageing in place and technologies of place: the lived experience of people with dementia in changing social, physical and technological environments[END_REF]. Rebentisch et al. [START_REF] Rebenitsch | An exploration of real-time environmental interventions for care of dementia patients in assistive living[END_REF] reckon that frustration/fear, confusion and anger were influential emotions that indicate the onset inappropriate behavior. Hoey et al. [START_REF] Hoey | Assisting persons with dementia during handwashing using a partially observable markov decision process[END_REF] consider the variables dementia level, awareness and responsiveness for their activity assistant. -Capabilities: Capabilities describe services or functionality of an entity.

PwDs expressed the desire to know more about whom they are interacting with [START_REF] Hawkey | Requirements gathering with alzheimer's patients and caregivers[END_REF], distinguish between similar items [START_REF] Wherton | Problems people with dementia have with kitchen tasks: The challenge for pervasive computing[END_REF] or how to use a device [START_REF] Hawkey | Requirements gathering with alzheimer's patients and caregivers[END_REF][START_REF] Wherton | Problems people with dementia have with kitchen tasks: The challenge for pervasive computing[END_REF]. This value helps to define semantics of entities, including competencies of people, types of places, and device functionalities. -Action: The action describes the goal oriented process an entity is performing [START_REF] Davies | Prototyping cognitive prosthetics for people with dementia[END_REF][START_REF] Hoey | Automated handwashing assistance for persons with dementia using video and a partially observable markov decision process[END_REF][START_REF] Phua | 2-layer erroneous-plan recognition for dementia patients in smart homes[END_REF]]. -Status: The status describes the current state of an entity. For people, this context type can describe their availability [START_REF] Mahmud | Dazed and confused considered normal: An approach to create interactive systems for people with dementia[END_REF]. For household appliances, the status can describe whether they are on or off [START_REF] Davies | Prototyping cognitive prosthetics for people with dementia[END_REF]. -Preferences: Assistive applications should consider the users' personal preferences [START_REF] Hawkey | Requirements gathering with alzheimer's patients and caregivers[END_REF]. This context type specifies stable personal preferences, meaning they are not subject to frequent change. Examples include language settings, date formats, or color settings; e.g. [START_REF] Davies | Prototyping cognitive prosthetics for people with dementia[END_REF].

Identity. Identity is needed to identify participants and their relationships. The name of an entity and Social relationship is of particular importance in dementia care. The social relationship context type links two or more persons. PwDs are increasingly dependent on their social context for care and social activities, e.g. [START_REF] Brittain | Ageing in place and technologies of place: the lived experience of people with dementia in changing social, physical and technological environments[END_REF][START_REF] Dröes | Dementia-related and other factors to be taken into account when developing ict support for people with dementia-lessons from field trials[END_REF][START_REF] Hawkey | Requirements gathering with alzheimer's patients and caregivers[END_REF][START_REF] Wherton | Technological opportunities for supporting people with dementia who are living at home[END_REF]. Furthermore, PwDs may experience difficulty to recognize how they are related to some people in their social context [START_REF] Hawkey | Requirements gathering with alzheimer's patients and caregivers[END_REF][START_REF] Wherton | Technological opportunities for supporting people with dementia who are living at home[END_REF].

Location. PwDs experience difficulty to orient themselves physical space, even in once familiar places [START_REF] Brittain | Ageing in place and technologies of place: the lived experience of people with dementia in changing social, physical and technological environments[END_REF][START_REF] Hawkey | Requirements gathering with alzheimer's patients and caregivers[END_REF]. They may not recognize their current location or remember how to reach a certain destination, for example their home. We identified the subtypes: orientation, position, relative location and semantic location. Orientation shows the direction in which to move from one place to another. The position determines the current location, for example for navigation assistance or monitoring. A semantic location denotes the meaning of a place. For example a "bakery" is a place that has a bread service. Hence, if the PwD's semantic location is "bakery", this person is in that place.

Time. Dementia affects episodic memory and temporal orientation [START_REF] Hawkey | Requirements gathering with alzheimer's patients and caregivers[END_REF][START_REF] Wherton | Technological opportunities for supporting people with dementia who are living at home[END_REF]. PwDs find it increasingly difficult to recall recent events, plan activities and how to relate to time. Precise time, time span and semantic time were identified. Precise time and time span are used to set reminders, either precise or within a certain threshold. Semantic time refers to an event entity in the user's context, for example lunch time or the time to watch the evening news.

Categories of Context-Aware Services

The following services were identified in our literature review:

Reminder. A reminder system is a memory assistant to plan and structure future events and activities. The system triggers reminders when certain conditions are met (e.g. time or location is reached). A notable example of context-aware reminders is the CybreMinder [START_REF] Dey | Cybreminder: A context-aware system for supporting reminders[END_REF]. In dementia care, HYCARE [START_REF] Du | Hycare: A hybrid context-aware reminding framework for elders with mild dementia[END_REF] supports setting reminders with several context types.

Activity Assistant. While reminder systems remind their users when activities are due, activity assistance tells users how to perform Activities of Daily Living (ADL). Activity assistants vary in activities they support, and the type of support they provide. The COGKNOW DayNavigator [START_REF] Davies | Prototyping cognitive prosthetics for people with dementia[END_REF] displays video sequences that show how to perform a task. The user interacts with a touch screen to play a sequence. Automatic activity assistants delve in the realm of artificial intelligence. The user's context is monitored to intervene when the user is deviating from the plan to complete the task (e.g. [START_REF] Hoey | Automated handwashing assistance for persons with dementia using video and a partially observable markov decision process[END_REF][START_REF] Phua | 2-layer erroneous-plan recognition for dementia patients in smart homes[END_REF][START_REF] Riley | An interactive tool to promote musical creativity in people with dementia[END_REF]). The development of intelligent activity assistants still faces many challenges [START_REF] Hoey | Rapid specification and automated generation of prompting systems to assist people with dementia[END_REF]. The COACH system is seen as the most sophisticated ADL assistant [START_REF] Hoey | Rapid specification and automated generation of prompting systems to assist people with dementia[END_REF]. It guides a PwD through the hand washing process [START_REF] Hoey | Automated handwashing assistance for persons with dementia using video and a partially observable markov decision process[END_REF].

Information Provider. Information providers use context to present relevant functions or information objects to the user. The COGKNOW DayNavigator is an example for the former. It offers simplified access to in-house devices and other services. The functions available change when the PwD is outdoor. An example for the latter are 'information appliances' [START_REF] Hawkey | Requirements gathering with alzheimer's patients and caregivers[END_REF]. These applications provide PwDs detailed information about previous, ongoing, and future activities. The MemoryLane project is exploring this area in dementia care [START_REF] Kikhia | Context-aware life-logging for persons with mild dementia[END_REF].

Communication and awareness. Communication and awareness systems extend social relationships and awareness beyond time and location. Communication is either asynchronous or synchronous. For example, the COGKNOW DayNavigator has a picture-based interface to a stationary and mobile phone. The awareness function makes one entity's context visible to others. An application of awareness is dementia care is monitoring. For example the KITE system [START_REF] Robinson | Keeping In Touch Everyday (KITE) project: developing assistive technologies with people with dementia and their carers to promote independence[END_REF] shows the location of the PwD to the CG. A context-aware system for PwDs was proposed by [START_REF] Mahmud | Dazed and confused considered normal: An approach to create interactive systems for people with dementia[END_REF]. The PwD uses a mobile phone to communicate with his social network. The system stores the type of social relationship for each contact and their availability. The personal CG can monitor the PwD's current location and schedule.

Navigation. A navigation system guides a user through physical space to a desired destination. Both the COGKNOW [START_REF] Mulvenna | Designing & evaluating a cognitive prosthetic for people with mild dementia[END_REF] and KITE [START_REF] Robinson | Keeping In Touch Everyday (KITE) project: developing assistive technologies with people with dementia and their carers to promote independence[END_REF] projects have a guidance function to help the PwD find their way home. A navigation system that considers location and time was proposed by [START_REF] Mahmud | Dazed and confused considered normal: An approach to create interactive systems for people with dementia[END_REF]. Todo items are placed in the PwD's time, location and social context. The navigation system helps the PwD to find the location of a given todo list item in a timely manner.

Life-Logging. Life-Logging complements a person's memory function. It records a constant stream of information during the day as images, sounds, location and time. The information is later processed to reconstruct the user's experiences [START_REF] Lee | Lifelogging memory appliance for people with episodic memory impairment[END_REF][START_REF] Kikhia | Context-aware life-logging for persons with mild dementia[END_REF].

Research Projects

× × × × × × COACH × × × × × × × × × COGKNOW × × × × × × × × × × × Context-Aware Wayfinder × × × × × CPVS × × × × × × ExPress Play × × MemExerciser × × ×
This paper considers the context-aware properties as an inherent part of most assistive applications for People with Dementia (PwDs) and their caregivers (CGs) to accommodate the users' needs and requirements in a dynamic environment. The motivation for this paper is to provide designers and developers with a tool to make an informed decision on the use of context and contextawareness. We approach by presenting the assistive applications identified in Sect. 1.2 and discussed in more detail in Sect. 4.1 from a context and contextaware perspective. Table 1 shows who the users were, the types of context-aware services they used (see Sect. 3.2) and where the applications were deployed (i.e. indoors or outdoors). Table 2 shows which context types (see Sect. 3.1) assistive applications relied on to provide those services to their users.

Context-aware Assistive Applications

The following projects were identified in Sect. 1.2 for our literature review: KITE. The Keeping In Touch Everyday (KITE) [START_REF] Robinson | Keeping In Touch Everyday (KITE) project: developing assistive technologies with people with dementia and their carers to promote independence[END_REF] project developed an outdoor navigation and communication system for PwDs. The Person with Dementia (PwD) carries a mobile device. It has a call button to contact the CG and a navigation function. The navigation function presents the PwD with instructions to find their way home. Additionally, the mobile device tracks the PwD's position as well as the device and alert state. These contextual information is presented to the CG via a web interface. [START_REF] Hoey | Assisting persons with dementia during handwashing using a partially observable markov decision process[END_REF][START_REF] Hoey | Automated handwashing assistance for persons with dementia using video and a partially observable markov decision process[END_REF][START_REF] Mihailidis | The coach prompting system to assist older adults with dementia through handwashing: An efficacy study[END_REF] is an activity assistant for the hand washing process. The system visually tracks the user's hand movement and process relevant items. The system bases its decisions on current observations and the user's level of dementia and emotions. Emotions are referred to as attitude (dementia level, awareness and responsiveness [START_REF] Hoey | Assisting persons with dementia during handwashing using a partially observable markov decision process[END_REF]). Only when the PwD experiences difficulties with the task, COACH presents the user with either visual or audio prompts. If prompts are ineffective and the PwD resume the task, the CG is called. The user's comportment influences the attitude and dementia variables over time.

COACH. COACH

COGKNOW. COGKNOW [START_REF] Davies | Prototyping cognitive prosthetics for people with dementia[END_REF][START_REF] Davies | A user driven approach to develop a cognitive prosthetic to address the unmet needs of people with mild dementia[END_REF][START_REF] Du | Hycare: A hybrid context-aware reminding framework for elders with mild dementia[END_REF][START_REF] Mulvenna | Designing & evaluating a cognitive prosthetic for people with mild dementia[END_REF] is a EU funded project to develop a comprehensive support system for people with mild dementia. COGKNOW extends the the realm of the PwD's residence. The PwD accesses services either through a stationary touchscreen interface or a mobile device. Activities are supported with a context-aware reminder system, video recorded instructions for a set of activities and simplified access to services. The reminder system triggers time-based and event-based reminders. Reminders are set by a CG [START_REF] Du | Hycare: A hybrid context-aware reminding framework for elders with mild dementia[END_REF]. Simplified access to music, radio and communication service are presented by both stationary and mobile device. Outdoors, the PwD has access to reminders and communication on the mobile device. An additional navigation function to get home is presented. Social communication is provided with a simplified interface to the phone. The PwD is presented with pictures of each CG to call. A help button is provided to directly call the main CG.

Context-Aware Wayfinder. [5] developed a navigation system for people with cognitive impairments, including dementia. The system guides their users to a destination by presenting images of the next waypoint and overlaying directions for the user's route. User and CG can call if needed. The system records the route progress and compliance. It presents this monitoring information to an authorized person.

ExPress Play. ExPress Play is an application for PwDs to engage in a creative activity through music. The system provides a touch screen and an easy to use interface. Users can select their emotion (happiness, sadness and anger) which influences the music being played and the visualization of the sound. The users interact with the application by dragging a finger across the screen. The system draws shapes depending on the speed of movement and plays different sounds [START_REF] Riley | An interactive tool to promote musical creativity in people with dementia[END_REF].

CPVS. The Cell Phone Video Streaming (CVPS) system [START_REF] Donnelly | A mobile multimedia technology to aid those with alzheimer's disease[END_REF] is a mobile reminder for people with mild dementia. The system consists of a smart phone for the PwD and a workstation with video camera for the CG. Reminders are video clips that are presented to the PwD. The PwD's CG records and schedules the reminders for the user. The smart phone downloads videos and notifies the PwD at the given time. The PwD needs to confirm the reminder by pressing a button. Reminders' confirmation state is accessible to the CG via a web-based interface.

MemExerciser. MemExerciser [START_REF] Lee | Lifelogging memory appliance for people with episodic memory impairment[END_REF] alleviates episodic memory impairment by recording and later replaying a PwD's passed experiences. The system consists of three parts: mobile sensors for life-logging, the CueChooser application to create a narrative of the PwD's experiences and MemExerciser to replay the narrative. A PwD carries a mobile camera with tree-axis accelerometer (Microsoft SenseCam), an audio recorder and a GPS. The camera and GPS record data in predefined time interval, the audio device records constantly. The recorded information is later preselected by the CueChooser application based on the context meta data. The CG further refines and tags the data to select good memory cues for the PwD. The PwD can partly compensate the memory impairment by "recalling" past experiences with the MemExerciser application.

Discussion

There is an increased focus on early detection and diagnosis of Alzheimer's disease [START_REF] Dekosky | Revision of the criteria for alzheimer's disease: A symposium[END_REF][START_REF] Prince | World alzheimer report 2011: The benefits of early diagnosis and intervention[END_REF]. A recent study commissioned by Alzheimer's Disease International [START_REF] Prince | World alzheimer report 2011: The benefits of early diagnosis and intervention[END_REF] found that early diagnosis and intervention were beneficial to Person with Dementias (PwDs). The motivation for our research is to facilitate the design of assistive applications for people at the early stage of dementia. In this section, we reflect on what we learned about the potential of assistive applications in dementia care to prolong independent living and how People with Dementia (PwDs) and their caregivers (CGs) can be involved in the design process.

Assistive Applications to Prolong independent Living

The purpose of our work is to help designers to map the needs and requirements of PwDs to the context dimensions activity, identity, location and time [START_REF] Dey | Towards a better understanding of context and contextawareness[END_REF]. Our literature study shows, that this field is drawing a lot of interest from the research community, which is reflected by several large scale research projects. However, only few applications were tested with the actual target group. This is not surprising, given the following two reasons. First, developing and testing for PwDs is a cumbersome process. The specific disease does not allow a traditional user-centered approach that designs for average users. Designers who collaborate with PwDs face a number of challenges in their effort to understand the requirements and needs of their users [START_REF] Lindsay | Empathy, participatory design and people with dementia[END_REF]37,[START_REF] Hawkey | Requirements gathering with alzheimer's patients and caregivers[END_REF]. They must develop systems that are tailored to individual users' context to reduce cognitive load, without putting users under pressure, who often provide only vague and sometimes conflicting information [START_REF] Lindsay | Empathy, participatory design and people with dementia[END_REF]37]. Second, there is no "user with dementia" archetype a designer can aim for. While PwDs share many characteristics, the advancement of the dementia syndrome is different for each person. Also the PwDs and their CGs's coping strategies will differ from case to case [START_REF] Perry | Preserving personhood: (re)membering the spouse with dementia*[END_REF]. Designers must therefore not only consider the PwD's cognitive abilities, but also personal and social aspects. This was the main reason our survey focused on projects in which PwDs participated as users. A challenge during our survey was to determine whether a piece of data is context, as defined by Dey and Abowd [START_REF] Dey | Towards a better understanding of context and contextawareness[END_REF] or not. During the study of assistive software for PwDs, the perspective of context and context-awareness provided us with a first impression of the role of context in the design process.

Design Recommendations

We summarize these findings as a set of basic design recommendations here. The recommendations are distilled from the practices presented by the projects and papers we studied for this survey. We listed good practices that occurred in one or more sources, and labeled them with a fitting title. With these design recommendations we want to provide a set of general guidelines and rules that lead to informed design for assistive applications for PwD. Since performing user evaluations with this specific user group is complex and often undesirable, having these guidelines can be of great help to create accessible assistive applications tailored according to the target group.

Represent time explicitly. PwD rely on a concrete notion of time and progress in time to alleviate the impacts of episodic memory impairment. Time is therefore an important non-functional requirement, which is present in all the services we studied. Time is often combined with other context information. E.g. a reminder for medication may also consider the location to present reminders when the PwD is in the right room. Or an activity assistant may adapt the triggering of prompts depending on the PwD's mood. An appropriate interactive system should schedule events in the interface and display reminders and other information as well as recording time stamps in live logging for later retrieval.

-This recommendation is based on [START_REF] Dröes | Dementia-related and other factors to be taken into account when developing ict support for people with dementia-lessons from field trials[END_REF][START_REF] Hawkey | Requirements gathering with alzheimer's patients and caregivers[END_REF][START_REF] Wherton | Technological opportunities for supporting people with dementia who are living at home[END_REF] -This recommendation has been applied by [START_REF] Chang | A context aware handheld wayfinding system for individuals with cognitive impairments[END_REF][START_REF] Davies | Prototyping cognitive prosthetics for people with dementia[END_REF][START_REF] Hoey | Automated handwashing assistance for persons with dementia using video and a partially observable markov decision process[END_REF][START_REF] Lee | Lifelogging memory appliance for people with episodic memory impairment[END_REF][START_REF] Riley | An interactive tool to promote musical creativity in people with dementia[END_REF][START_REF] Robinson | Keeping In Touch Everyday (KITE) project: developing assistive technologies with people with dementia and their carers to promote independence[END_REF] Label temporal events. Temporal impairment can be alleviated by giving a meaning to temporal events. PwDs find it increasingly difficult to make sense of time. This is referred to as semantic time in Table 2. Semantic time is inherently linked to other context dimensions. For example "lunch" is the time when a person eats at home, normally around 12:00h.

-This recommendation is based on [START_REF] Dröes | Dementia-related and other factors to be taken into account when developing ict support for people with dementia-lessons from field trials[END_REF][START_REF] Hawkey | Requirements gathering with alzheimer's patients and caregivers[END_REF][START_REF] Wherton | Technological opportunities for supporting people with dementia who are living at home[END_REF] -This recommendation has been applied by [START_REF] Davies | Prototyping cognitive prosthetics for people with dementia[END_REF][START_REF] Donnelly | A mobile multimedia technology to aid those with alzheimer's disease[END_REF] Make location data accessible at all times. Use location in the dialog with PwDs to mitigate topological and geographical disorientation. A typical service for the PwD is a navigation system that guides the person from its current location to a destination. Location also provides tracking capabilities to locate the PwD and trigger alerts. Semantic location is a location in combination with other context information. For example a shop or a rendezvous point, i.e. a place where two or more people are to meet at a given time. Location also manifests itself in the interface as choices of information of functionalities that are presented to the user. For example a controller removes access to the radio once the PwD leaves the house.

-This recommendation is based on [START_REF] Brittain | Ageing in place and technologies of place: the lived experience of people with dementia in changing social, physical and technological environments[END_REF][START_REF] Dröes | Dementia-related and other factors to be taken into account when developing ict support for people with dementia-lessons from field trials[END_REF][START_REF] Hawkey | Requirements gathering with alzheimer's patients and caregivers[END_REF] -This recommendation has been applied by [START_REF] Chang | A context aware handheld wayfinding system for individuals with cognitive impairments[END_REF][START_REF] Davies | Prototyping cognitive prosthetics for people with dementia[END_REF][START_REF] Donnelly | A mobile multimedia technology to aid those with alzheimer's disease[END_REF][START_REF] Robinson | Keeping In Touch Everyday (KITE) project: developing assistive technologies with people with dementia and their carers to promote independence[END_REF] Explicitly and uniquely identify all people, concepts and objects in the user interface. To avoid confusion, label all concepts, people and objects that might be accessed through the user interface. This needs to be done in an unambiguous way to avoid confusing the PwD. E.g. when to contact someone using a contact list, people with similar names could cause confusion. In this situation extra information needs to be added to increase the discrepancy between similar items. PwD tend to misplace objects or be unsure which object to use. Activity assistants and reminders need to know which objects the PwD needs for their tasks. Identity can also be combined with subtypes of activity, such as the status of kitchen appliances.

-This recommendation is based on [START_REF] Dröes | Dementia-related and other factors to be taken into account when developing ict support for people with dementia-lessons from field trials[END_REF][START_REF] Hawkey | Requirements gathering with alzheimer's patients and caregivers[END_REF][START_REF] Wherton | Technological opportunities for supporting people with dementia who are living at home[END_REF] -This recommendation has been applied by [START_REF] Chang | A context aware handheld wayfinding system for individuals with cognitive impairments[END_REF][START_REF] Davies | Prototyping cognitive prosthetics for people with dementia[END_REF][START_REF] Hoey | Automated handwashing assistance for persons with dementia using video and a partially observable markov decision process[END_REF][START_REF] Robinson | Keeping In Touch Everyday (KITE) project: developing assistive technologies with people with dementia and their carers to promote independence[END_REF] Put the social network central. The first line of help comes from other people: CG, other relatives, medical professionals and friends. The interface can reassure PwD that there are people they know reachable for help by including a contact list. For example: one presentation of social relationships is an address book that lets a PwD call a contact. An alerting service uses social relationship to send notifications and escalate alerts to multiple contacts is an example for a background service. Additional information about the contacts, such as competencies or availability, can help to route notifications to contacts that are the most likely to help.

-This recommendation is based on [START_REF] Brittain | Ageing in place and technologies of place: the lived experience of people with dementia in changing social, physical and technological environments[END_REF][START_REF] Dröes | Dementia-related and other factors to be taken into account when developing ict support for people with dementia-lessons from field trials[END_REF][START_REF] Monk | Simple, social, ethical and beautiful: requirements for uis in the home[END_REF][START_REF] Wherton | Technological opportunities for supporting people with dementia who are living at home[END_REF] -This recommendation has been applied by [START_REF] Chang | A context aware handheld wayfinding system for individuals with cognitive impairments[END_REF][START_REF] Davies | Prototyping cognitive prosthetics for people with dementia[END_REF][START_REF] Donnelly | A mobile multimedia technology to aid those with alzheimer's disease[END_REF][START_REF] Hoey | Automated handwashing assistance for persons with dementia using video and a partially observable markov decision process[END_REF][START_REF] Robinson | Keeping In Touch Everyday (KITE) project: developing assistive technologies with people with dementia and their carers to promote independence[END_REF] Show the current activity at all time. The assistive application should show what the currently planned activity is at all times. This relies on an agenda that is available with the PwD daily activities. We found "user activity" is, together with time, the most important but also the most demanding to incorporate into the system design. Preferably, the previous activity and next planned activity are included in the user interface design.

-This recommendation is based on [START_REF] Brittain | Ageing in place and technologies of place: the lived experience of people with dementia in changing social, physical and technological environments[END_REF][START_REF] Hawkey | Requirements gathering with alzheimer's patients and caregivers[END_REF][START_REF] Wherton | Technological opportunities for supporting people with dementia who are living at home[END_REF][START_REF] Wherton | Problems people with dementia have with kitchen tasks: The challenge for pervasive computing[END_REF] -This recommendation has been applied by [START_REF] Davies | Prototyping cognitive prosthetics for people with dementia[END_REF][START_REF] Donnelly | A mobile multimedia technology to aid those with alzheimer's disease[END_REF][START_REF] Hoey | Automated handwashing assistance for persons with dementia using video and a partially observable markov decision process[END_REF][START_REF] Robinson | Keeping In Touch Everyday (KITE) project: developing assistive technologies with people with dementia and their carers to promote independence[END_REF] Foster Personal Identity. PwDs and their CGs are very sensitive about how they are perceived by others. Maintaining their personal identity, respect and dignity is vital for PwDs and their CGs. Assistive applications should be appealing to their users and not be perceived as stigmatizing. In addition to functional requirements, the design must therefore consider the individuals' preferences and blend into their environment.

-This recommendation is based on [START_REF] Brittain | Ageing in place and technologies of place: the lived experience of people with dementia in changing social, physical and technological environments[END_REF][START_REF] Dröes | Dementia-related and other factors to be taken into account when developing ict support for people with dementia-lessons from field trials[END_REF][START_REF] Hawkey | Requirements gathering with alzheimer's patients and caregivers[END_REF]21,[START_REF] Monk | Simple, social, ethical and beautiful: requirements for uis in the home[END_REF][START_REF] Newell | User-sensitive inclusive design[END_REF] -This recommendation has been applied by [START_REF] Davies | Prototyping cognitive prosthetics for people with dementia[END_REF][START_REF] Donnelly | A mobile multimedia technology to aid those with alzheimer's disease[END_REF][START_REF] Riley | An interactive tool to promote musical creativity in people with dementia[END_REF][START_REF] Robinson | Keeping In Touch Everyday (KITE) project: developing assistive technologies with people with dementia and their carers to promote independence[END_REF]

Conclusion

The context and context-awareness classification and our design recommendations presented are by no means a substitute for consulting medical professional and people affected by dementia. Our aim is to provide a tool to assist a preparatory investigation for the design and development of context-aware applications for Person with Dementia (PwD). The framework informs developers and designers about possible use of context for their applications. Validation with the target group remains the best approach, but given the condition of the test users it is extremely difficult to do actual user trials. Our framework upon previous research and development in this domain and makes the previous experiences in building such system more accessible for developers and designers creating a new system. When use cases are defined for a project, our reference framework helps to identify the (1) dimensions of context that need to be taken into account, (2) provide a set of examples of concrete implementations for these dimensions by referring to relevant research projects and (3) helps to uncover important context dimensions that might otherwise easily missed while designing an assistive application for People with Dementia (PwDs).

Table 1 .

 1 Categories of context-aware applications in dementia care

			Project						Category
	Name	Reference	Users	Settings	Activity Assis-	tant	Reminder	Life-Logger	Information	Provider	Communication	Navigation
	KITE	[45]	People with mild to mod-	outdoor							×	×
			erate dementia, caregivers
	COACH	[18, 20,	People with moderate-to-	indoor	×					×
		29]	severe dementia
	COGKNOW	[6, 32] People with mild demen-	indoor,	× ×		×		×	×
			tia, caregivers		outdoor
	Context-	[5]	Mental	retardation,	indoor,							×	×
	Aware		epilepsy, organic depres-	outdoor
	Wayfinder		sion, Parkinsonś Disease,
			dementia, schizophrenia,
			organic brain syndrome
	CPVS	[12]	People without cognitive	indoor,			×				×
			impairment, people with	outdoor
			mild dementia, caregivers
	ExPress Play	[44]	People with mild to mod-	indoor	×
			erate dementia
	MemExerciser	[24]	People with mild cog-	indoor,				×
			nitive impairment, mild	outdoor
			Alzheimer,moderate
			Alzheimer, caregivers.

Table 2 .

 2 Context Types in dementia care

	Context Type

Acknowledgments

Part of the research described in this article was performed in the context of the IBBT project AToM. This project is cofunded by the IBBT (Interdisciplinary institute for Technology), a research institute founded by the Flemish Government. Companies and organizations involved in the project are Televic Healthcare NV, GS1 Belgium & Luxembourg vzw, Woon-en Zorgcentrum Sint-Jozef vzw, Katholieke Hogeschool Limburg, Ter Linden vzw, Pyxima NV, Bedrijfstechnische Eenheid Broeders Alexianen, with project support of IWT.


Yuan Jia
email: jiayuan@umail.iu.edu

Marta Kristin Larusdottir

Åsa Cajander
email: asa.cajander@it.uu.se

The Usage of Usability Techniques in Scrum Projects

Keywords: Usability techniques, User centred design, user involvement, usability, agile software development, Scrum

Over the past decades, usability techniques have been introduced into software development practices. At the same time many software development teams have started to use the agile development process -Scrum -to plan and organize their software projects. The focus of this study is to explore how usability techniques are integrated during software development in Scrum projects. The most commonly used usability technique in Scrum projects is workshops, followed by lo-fi prototyping, interviews and meetings with users, all used by more than half of the participants. The technique that is most frequently used is lo-fi prototyping used by more than half of the participants two to four times a month. All these usability techniques are informal, meaning that these techniques can be used quickly without much preparation. Formal usability evaluation with users is a highly ranked technique by the participants but not commonly used by them.

Introduction

Scrum, as one of the agile software development processes, has been gaining popularity in software development over the last few years to plan and organize software development projects [START_REF] Larusdottir | User involvement in Icelandic software industry[END_REF]. In Scrum the projects are split up in two to four weeks long periods called sprints, each ending up with a potential shippable product that the end users should be able to use right after delivery. In Scrum self organizing and well compounded software development teams are heavily emphasized, typically with six to eight interdisciplinary team members [START_REF] Schwaber | Scrum development process[END_REF]. The main characteristics of the process are simplicity and speed [START_REF] Abrahamsson | New Directions on Agile Methods: a Comparative Analysis[END_REF] which possibly is one of the reasons for its popularity in industry. One of the benefits of using agile development processes was claimed to be that customers' needs are taken more into account than when developing software using more traditional processes [START_REF] Schwaber | Scrum development process[END_REF]. Traditional Scrum has been criticized for not involving real users in their software process and for not adequately addressing their usability needs [START_REF] Singh | U-SCRUM: An Agile Methodology for Promoting Usability[END_REF]. One of the main conclusions in an extensive literature study on the integration of the usability needs into agile processes is that the end user needs have not yet been sufficiently included in the agile development processes [START_REF] Sohaib | Integrating usability engineering and agile software development: A literature review[END_REF].

At the same time as Scrum became popular in industry, the term usability emerged during the mid 1980s, and was accepted in the 1990s by the software industry. This was partly as a response to the new challenges that web-based software -to be used by a large number of diverse users -put on IT (Information Technology) professionals. However, the body of knowledge of usability is large and includes various perspectives from usability engineering to more context-oriented approaches and these have not yet been accepted fully by industry [START_REF] Bygstad | Software development methods and usability: Perspectives from a survey in the software industry in Norway[END_REF].

For the past decade, usability techniques used in various areas in the industry have been studied by researchers. For example, Venturi & Troost [START_REF] Venturi | Survey on the UCD integration in the industry[END_REF] studied how User-Centered Design (UCD), one of the main approaches in the usability field, was integrated in software development. Larusdottir et al. [START_REF] Larusdottir | User involvement in Icelandic software industry[END_REF] studied the effect of using a particular development process in industry on the use of user involvement techniques. In that study, about half of the participants were using their own process to plan their work and about one third were using Scrum as their development process. When asked about, if usability is important the participants using the Scrum process were the most negative ones. The most popular user involvement method was meetings with users used by almost all the participants. The use of user involvement methods varied quite extensively according to which process is used for software development. The results from these studies motivated us to examine the use of usability techniques in projects using one particular process, namely the Scrum process.

This paper describes and discusses the results of a survey study on how usability techniques are being used in software projects using the Scrum process to plan and organize the work. The focus of the study is to explore what usability techniques are used, if the usage of one technique is correlated with the usage of the other techniques, how often the techniques are used and how useful they are for IT professionals. The motivation for the study is to gain understanding of what IT professionals need to be able to integrate usability activities more extensively while using the Scrum process in software development.

Background

Several studies have been conducted on how usability techniques are integrated into software development. It has been explored in some of the studies what software development processes are used, but often it is not analyzed how or if the software process affects how usability techniques were used. In this chapter an overview is given of some of the current literature on how usability techniques have been integrated in software development in industry.

Bygstad, Ghinea, and Brevik [START_REF] Bygstad | Software development methods and usability: Perspectives from a survey in the software industry in Norway[END_REF] surveyed professionals working at Norwegian IT companies to investigate the relationship between software development methodologies and usability activities. In their findings, there was a gap between intention and reality. The IT professionals expressed interests and concerns about the usability of their products, but they were less willing to spend resources on it in industrial projects with time and cost constraints. The results of their survey also revealed that the IT professionals perceived usability activities and software development methods to be integrated, which the authors believed is a positive sign.

Bark et al. [START_REF] Bark | Use and usefulness of HCI methods: Results from an exploratory study among nordic HCI practitioners, In: People and Computers XIX -The bigger picture[END_REF] conducted a survey on the usage and usefulness of HCI methods during different development phases. They examined whether the type of the software projects had any effects on HCI practitioners' perception of the usefulness of the methods. The results show that there was fairly little correlation between the frequency of using a particular technique and how useful it was perceived by the HCI practitioners. One conclusion in the study is that HCI practitioners tend to have a personal and overall evaluation of the different techniques rather than evaluating the actual usefulness of the methods in their daily work when developing particular software.

An international web-based survey by Monahan et al. [START_REF] Monahan | An Investigation into the use of Field Methods in the Design and Evaluation of Interactive Systems[END_REF] reported the state of using several field study techniques and how effective they were considered to be by usability practitioners in education and industry. The results show that more than half of the respondents rated observations as an extremely effective method and about 40% of the respondents rated user testing as extremely effective. The most influential factor for choosing a method for participants working in the software industry was time constrains.

Venturi, Troost and Jokela [START_REF] Venturi | People, organizations, and processes: An Inquiry into The Adoption of User-Centered Design in Industry[END_REF] investigated the adoption of user centred design (UCD) in software industry. The results of the study show that the most frequently used method was user interviews. Additionally, hi-fi and low-fi prototyping methods were frequently used. Overall, the most frequently used evaluation methods are qualitative, allowing rapid feedback to the design activities using expert and heuristic evaluation or "quick and dirty" usability test methods. The results also show that UCD methods are typically used during the early phases of the product life cycle.

A survey study on the usage of 25 usability techniques was conducted in Sweden by Gulliksen et al. [START_REF] Gulliksen | Making a Difference: A Survey of The Usability Profession in Sweden[END_REF]. The results show that the usability techniques that received the highest rating by the usability professionals were those that were informal, involved users and were concerned with design issues. Techniques such as expert-based evaluations and benchmarking that do not involve users, received the lowest ratings by the usability professionals. There was a general agreement among the participants that it is important to integrate usability techniques into the software development process they were using. Some participants mentioned difficulties during the integration, especially those that were using RUP (Rational Unified Process) as their development process.

Research Method

The research method in this study was a questionnaire-based survey. The questionnaire was distributed to IT professionals who were experienced in using Scrum as their software development process and were using usability techniques in their software development.

In the survey we asked IT professionals about their usage of different usability techniques and how useful they rated the techniques. We define usability techniques as the various techniques and methods used in software development to enhance the usability of an IT system.

Survey Conduction

The survey was constructed in QuestionPro, which is an online survey tool (http://www.questionpro.com/). The survey included 41 multiple-choice questions and 5 open questions. The questions were developed according to a literature review and interviews with two IT professionals experienced in using Scrum.

The list of 13 usability techniques was a result from a literature review based on Gulliksen et al. [START_REF] Gulliksen | Making a Difference: A Survey of The Usability Profession in Sweden[END_REF], Venturi et al. [START_REF] Venturi | People, organizations, and processes: An Inquiry into The Adoption of User-Centered Design in Industry[END_REF] and Larusdottir et al. [START_REF] Larusdottir | User involvement in Icelandic software industry[END_REF]. However, not all techniques from these studies were chosen since we did not want the list to be too long and risk a low response rate. We chose 5 data gathering techniques: interviews, workshops, questionnaires, meetings with users and field studies, three techniques often used for analysis: usability goals, scenarios and personas, two types of design techniques: lo-fi prototyping and digital prototyping and three techniques for evaluation: formal usability evaluations with users, informal evaluations with users and one expert evaluation technique, the heuristic evaluation. With this selection we wanted to cover a wide range of usability techniques used in software development practice today. The respondents were asked if they had used any other techniques. Two participants responded to that question naming one technique each.

The questions in the questionnaire were grouped into four sections: (1) Information on the companies/organizations and experience of the respondents, (2) the Scrum process in one particular project, (3) the usability techniques that have been used in the particular Scrum project and (4) open questions on usability activities.

Two pilot tests were conducted in order to enhance the quality of the survey. The participants were experts in HCI working in the software industry and using Scrum as their development process. To estimate the approximate time for taking the survey, the first pilot test was timed without any interruption. An interview was conducted after the test. Think-aloud method was used in the second pilot test to detect problems while answering the survey.

Survey Distribution

The survey link was distributed in three different ways. First, the survey link was sent to an email list of software development companies in the Stockholm and Uppsala area. The email list was provided by the Uppsala Tax Office and Lokaldelen, which is a website offering information on companies in Sweden (http://www.lokaldelen.se/). The second way of sending the survey was through directly contacting the target respondents. In order to get more responses, the survey link was also posted on an online discussion group called Scrum Alliance, (http://groups.google.com/group/ scrumalliance) which is an international forum for IT professionals using Scrum.

During a period of 40 days, from 25 th April 2011 to 4 th June 2011, totally 49 respondents responded to the survey and 35 of the participants completed all the questions.

Respondents

Respondents came from 7 countries around the world. The vast majority, 78% of the respondents came from Sweden, the rest of them came from China (8%), USA (6%), France (2%), Greece (2%), Lithuania (2%) and South Africa (2%).

About 70% of the respondents had a university degree either a Master or a Bachelor degree. Fourteen out of 49 respondents were certified Scrum Masters, which is a particular role while using the Scrum process. The result shows that about 30% of the respondents had programming as their main job role and 20% responded that usability engineering was their main job role. Around 20% of respondents had a management role in their projects. Others worked for example on code design (10%), on requirement gathering (10%) and on UI design (8%). None of the participants indicated that software testing or evaluation was their main job task.

About one third of the respondents were employed at companies or organizations having up to 50 employees, one third of the respondents at companies/organizations having 50-249 employees and one third of respondents in companies/organizations that had more than 250 employees. Over 40% of the IT professionals worked on projects for the Internet or the e-commerce area, around 20% worked in the IT industry in general, about 20% were working in particular domains like in the health and medical sector, telecommunication sector or in the financial sector. Respondents also reported some other business types that were not listed in the question.

In the second part of the survey the respondents were asked to select one particular project to give information on. Seventy present of respondents had been working on multiple projects simultaneously for the last 3 months. When asked about the type of the project that they had selected, about 40% responded that the particular project was web related. About 25% of the professionals were developing software products for sale, around 15% were developing software systems for clients and about 15% were developing internal software systems. The remaining respondents mentioned developing other types of systems, including embedded software systems and hardware systems.

Results

This chapter presents the results on what usability techniques are used by IT professionals, how often they use the techniques, how the IT professionals rate the usefulness of the usability techniques and how the usage of one usability technique is correlated with the usage of other usability techniques.

Usability Techniques Used in Scrum Projects

Before asking about the usability techniques, all techniques were listed and explained to make a common understanding of the steps taken while using the techniques and what the names of the techniques actually meant. In Table 1 the usability techniques are listed according to how many respondents had used them. The results in Table 1 show that workshops are the most commonly used usability technique in Scrum projects followed by lo-fi prototyping, interviews and meetings with users. Heuristic evaluation was used by only 11% of the participants and questionnaires were used by about 20% of the participants. Evaluations with users are not that common, about one fourth of the participants had conducted informal evaluation with users and about one third of the participants had conducted formal usability evaluation with users.

Table 1. The Usage of Usability Techniques

The Frequency of Using Usability Techniques

The respondents were asked about the frequency of using the usability techniques during one Scrum project. The results from that question are shown in Table 2. The technique that is most frequently used is lo-fi prototyping, used once a week by about 40% of the respondents. About half of the participants use scenarios two to four times a month. About 75% of respondents who had used questionnaires said that they used that technique only once a year or less frequently. About 40% of the respondents used personas once a year or less than that. The remaining techniques were used two to six times a year.

The Ratings of the Usability Techniques

The ratings of how useful the respondents find the usability techniques are presented in Table 3. The participants were asked to rate the techniques on a five-point scale from very good to very bad.

Table 3. The Rating of the Usability Techniques * N represents the number of respondents who had used the technique in their projects. ** With users participating.

The result reveals that about 75% of the respondents thought that formal usability evaluation with users was very good and about 60% rated field studies and digital prototyping as very good. Around half of the respondents said usability goals, lo-fi prototyping worked very well. No participant rated questionnaires as a very good technique.

If the ratings "Very good" and "Fairly good" are combined, the top five rated usability techniques used by IT practitioners are: 1) workshops 2) informal usability evaluation with users 3) meetings with users 4) scenarios and 5) formal usability evaluation with users.

Usability techniques

Correlation of the Usage of Usability Techniques

Some significant and interesting correlations were found among the usage of usability techniques in Scrum projects. Results in Table 4 shows that there were totally six usability techniques, which had significant correlations with field studies. These techniques are interviews, workshops, meetings with users, personas, lo-fi prototyping and heuristic evaluation. Interviews are significantly correlated with meetings with users. Questionnaires are significantly correlated with digital prototyping, formal usability evaluation with users and informal usability evaluation with users. Workshops are significantly correlated with personas. Usability goals are significantly correlated with scenarios. Digital prototyping is significantly correlated with heuristic evaluation. Lo-fi prototyping is significantly correlated with personas and formal usability evaluation with users. + Represents that the correlation is significant at the 0.05 level * Represents that the correlation is significant at the 0.01 level Some of these techniques are related in character like meetings with users and interviews could be conducted in a similar way. Furthermore, interviews are often conducted in the field, so the correlation between field studies and interviews could be expected. On the contrary, the correlation between field studies and heuristic evaluation is rather surprising. The fact that there is a correlation between using the techniques does not mean that these techniques are necessarily used at the same time, but that an IT professional is more likely to conduct heuristic evaluation if that person conducts field studies. Furthermore, a correlation between formal usability evaluation with users and digital prototypes could be expected, but formal evaluations are correlated only with lo-fi prototypes. Questionnaires seem to be used in correlation with evaluation with users, both during formal and informal evaluation. Usability goals seem to be stated in correlation with writing scenarios.

Discussion

The survey asked the respondents to rate both the usefulness and how often they use the 13 usability techniques. The results show that the top five rated usability techniques used by practitioners are: 1) workshops 2) informal usability evaluation with users 3) meetings with users 4) scenarios and 5) formal usability evaluation with users. This result is partly consistent with the practitioners' perception of the effectiveness of usability techniques in software development projects presented by Gulliksen et al. [START_REF] Gulliksen | Making a Difference: A Survey of The Usability Profession in Sweden[END_REF]. The top five rated techniques in that study were: 1) the thinkaloud method 2) lo-fi prototyping 3) interviews 4) field studies and 5) scenarios.

Our results show that the top five frequently used usability techniques by IT professionals are: 1) workshops 2) lo-fi prototyping 3) interviews 4) meeting with users and 5) scenarios. This result is also partly consistent with the study from Venturi et al. [START_REF] Venturi | People, organizations, and processes: An Inquiry into The Adoption of User-Centered Design in Industry[END_REF]. Their top five frequently used usability techniques are: 1) user interviews 2) heuristic evaluation 3) qualitative usability evaluations 4) hi-fi prototyping and 5) lo-fi prototyping.

When comparing our results on the top five rated and frequently used usability techniques with those of other studies, it is difficult to draw conclusions regarding the differences. First, the study presented in this paper provided an exact description for each usability technique in the survey, which was not done in the other studies. It may not be viable to compare two ranks of usability techniques when the researchers and the respondents may have had different understanding of what it includes to use a particular usability technique. Secondly, the usability techniques used in the different studies were not the same. For example, workshops are rated as the top usability technique in this study, but workshops are not included in the study by Gulliksen et al. [START_REF] Gulliksen | Making a Difference: A Survey of The Usability Profession in Sweden[END_REF]. Moreover, all the usability techniques mentioned in this study were used in software project using the software development process Scrum, but the other two papers are about software development in general.

However, despite these differences some interesting things are worth noticing when comparing the results from the studies. The results from this study show that heuristic evaluation is not often used but the techniques get reasonable ranking in this study and the results from Venturi et al. [START_REF] Venturi | People, organizations, and processes: An Inquiry into The Adoption of User-Centered Design in Industry[END_REF] show that heuristic evaluation was one of the top five frequently used techniques. One possible explanation to this difference is that heuristic evaluation may not fit well in the Scrum process. Another possible reason is that the usage of heuristic evaluation as an evaluation method has been decreasing in software development in general, and that the survey results from this study, which was conducted in 2011, indicate a general trend.

The usefulness rated by the participants and the frequency of using the techniques are not correlated. For example, about 75% of the respondents consider the technique formal usability evaluation with users very good, but only about 30% used it in their projects. One possible explanation for this inconsistency is that the most important characteristic of Scrum is speed. The duration of one Scrum sprint usually last two to four weeks, but sometimes practitioners need longer time to use a particular usability technique. It usually takes practitioners long time to prepare formal usability testing, recruit participants and conduct the tests, for example.

The techniques digital prototyping and field studies were also rated highly and used two to six times a month. Still, these techniques were only used by one third of the respondents. The technique lo-fi prototyping is more frequently used than the technique digital prototyping. Still the usefulness of digital prototypes was higher ranked than the usefulness of lo-fi prototyping. One of the main advantages of lo-fi prototyping is its quickness and accessibility to any team member in the development process. One explanation could be the focus on speed during Scrum projects.

As shown in the results of the correlation among usability techniques, field studies are significantly correlated with interviews, workshops, meetings with users, personas, lo-fi prototyping and heuristic evaluation. Field studies can help collecting and preparing interview questions and the technique interviews also can provide some valuable information for the process of the field studies. The correlation between field studies and heuristic evaluation is more surprising, because these types of evaluations are rarely conducted in the field. Furthermore, the knowledge that is needed to use the two techniques is not that related. Another technique -formal usability evaluation with users -has strong correlation with the technique questionnaires. One reasonable explanation is that questionnaires can be used to prepare the test tasks or as a post-test survey for the formal usability evaluation with users. Formal evaluation has also a correlation with lo-fi prototypes, which is positive, because it has been suggested in the HCI literature for many years that evaluations should start as soon as possible during the software development.

Conclusions

This study investigates the integration of usability techniques in software projects using the Scrum process in industry. The findings from the study indicate that the technique workshops are the most commonly used usability technique in Scrum projects, followed by: lo-fi prototyping, interviews, meetings with users and scenarios. Besides, the top five highest rated usability techniques according to usefulness for the IT professionals are: 1) workshops 2) informal usability evaluation with users 3) meetings with users 4) scenarios and 5) formal usability evaluation with users. A novel contribution of this study is that there were significant correlations of the usage among different usability techniques in Scrum projects. If IT professionals use workshops they are more likely to use personas is an example of these correlations.

Table 2 .

 2 The Frequency of Using the Usability Techniques * N represents the number of respondents who had used the technique in their projects. ** With users participating.

	Usability techniques			Used	Total	Percentage
	Workshops			30	41	73%
	Lo-fi prototyping			20	36	56%
	Interviews			25	46	54%
	Meetings with users			21	40	53%
	Scenarios			17	36	47%
	Digital prototyping			17	36	47%
	Personas			15	35	43%
	Field studies			17	40	46%
	Usability goals			15	38	40%
	Formal usability evaluation with users		11	36	31%
	Informal usability evaluation with users		8	35	23%
	Questionnaires			9	42	21%
	Heuristic evaluation			4	35	11%
	Usability techniques	Once a	2 -3	7 -12	2 -6	Once	N*
		week or	times a	times	times	a year
		more	month	a year	a year	or less
	Interviews	9%	13%	22%	44%	13%	25
	Questionnaires	0%	0%	0%	25%	75%	9
	Workshops	7%	7%	25%	50%	11%	30
	Meetings with users	15%	10%	30%	35%	15%	21
	Field studies	0%	0%	7%	53%	40%	17
	Usability goals	21%	7%	29%	29%	14%	15
	Scenarios	24%	24%	18%	24%	12%	17
	Personas	6%	19%	13%	25%	38%	15
	Digital prototyping	24%	12%	6%	35%	24%	17
	Lo-fi prototyping	40%	20%	15%	20%	5%	20
	Formal usability evaluation**	0%	0%	18%	82%	0%	11
	Informal usability evaluation**	25%	25%	13%	50%	13%	8
	Heuristic evaluation	0%	25%	0%	50%	25%	4

Table 4

 4 Correlation of the Usage of Usability Techniques

		Interviews	Questionnaires	Workshops	Meetings with user	Field study	Usability goals	Scenarios	Personas	Digital prototyping	Lo-fi prototyping	Formal usability evaluation	Informal usability evaluation	Heuristic evaluation
	Interviews				+	*
	Questionnaires									+		*	+
	Workshops					+			*
	Meetings with users	+				+
	Field studies	*		+	+				+		+			*
	Usability goals							+
	Scenarios						+
	Personas			*		+					+
	Digital prototyping		+											+
	Lo-fi prototyping					+			+			+
	Formal usability		*								+
	evaluation
	Informal usability		+
	evaluation
	Heuristic					*				+
	evaluation

Acknowledgements

We would like to thank all the participants in the study that took their time in answering the questionnaire. Additionally, we would like to thank the PhD student Simon Tschirner and the former PhD students Niklas Hardenborg and Stefan Blomkvist in Human Computer Interaction in Uppsala University for taking part in piloting the questionnaire. Furthermore, we would like to thank the research and teaching assistant Tao Yang at School of Informatics in Indiana University in U.S. for his valuable comments when reviewing the paper.