14 1 Disability and Assistive Technology Systems

Assistive technology outcomes have both objective and subjective components, with the subjective component particularly important. Since one of the potential benefits of assistive technology is improvement of quality of life, outcome measurements frequently focus on quality of life. The measurement of quality of life in the medical context considerably predates the development of specific outcome measures for assistive technology. However, it has the disadvantage of a narrow focus on health and wellness rather than a wider understanding of quality of life, and using measures of unaided functioning that automatically classify disabled people as having a reduced quality of life due to their impairments.

Six different assistive technology specific outcome measures, as well as an ongoing project, have been discussed. All the approaches have advantages and disadvantages and a universal standard has not yet been developed. The different approaches have been influenced to different extents by health related quality of life approaches and associated assumptions that disabled people have a reduced quality of life. However, in most cases such inappropriate assumptions could be edited out by changes in the wording. There may also be advantages in several assessment procedures with different areas of application continuing to be used rather than a de facto standard being developed. Most of the measures have been tested both through studies of their performance with different groups of endusers and by experts. However, there is a need for more comparative studies of the different measures, as well as studies outside Europe and the U.S.A.

The current assessment procedures are available in English and sometimes also other European languages and have been developed in Europe or the U.S.A. There is therefore a need for further research to modify these instruments or develop others for use in other parts of the world or even worldwide, as well as to translate the instruments into a much wider range of different languages. It would be useful to have a global standard instrument that is universally applicable and could be translated into any language. However, this may not be feasible, due to differences in culture, lifestyle and attitudes in different parts of the world. Disabled end-users of assistive technology should have a much more central role in future research on outcome measures to ensure that the approaches are relevant to them as well as to the professionals involved in providing assistive technology.

Assistive technology has a potentially important role to play in increasing quality of life by opening up new opportunities to disabled people and increasing the range of options open to them. This, then, is the subject of this book, the development of assistive technology to be used by blind and visually impaired people to increase their options and opportunities.

1.3 Modelling Assistive Technology Systems

There are a number of different definitions of assistive technology. The definition used here will be based on the social model of disability. Other commonly used definitions of assistive technology are based on the medical model of disability.

In terms of the social model the aim of assistive technology is to overcome the gap between what a disabled person wants to do and what the existing social

infrastructure allows them to do. It consists of equipment, devices and systems that can be used to overcome the social, infrastructure and other barriers experienced by disabled people that prevent their full and equal participation in all aspects of society. Assistive technology is used in a social, cultural, political, economic and environmental context. This context may facilitate the development and use of assistive technology, pose barriers and constraints or be neutral. Although the infrastructure for the provision of assistive technology is more developed in the industrialised countries, assistive technology is required in the so-called developing countries as well and should be available worldwide. Users and potential users of assistive technology also vary greatly in their characteristics, interests, skills, values and impairments. Assistive technology is also required for a wide range of different types of tasks and applications.

As a result of this great diversity in (potential) end-users, applications and context there is a strong need for a simple, effective and unified modelling framework to support the ongoing dialogue between end-users, therapists, social workers, funding bodies and the engineering community and other researchers and professionals working in the area of assistive technology. A unified modelling framework and terminology will also enable the common structure of assistive technology systems to be understood by different professional domains and provide a pedagogical basis for education and training courses in the assistive technology field. The objectives for the modelling framework can be stated as follows:

1.It should be applicable to any assistive technology system.

2.It should be possible to use the modelling framework to provide a classification of assistive technology systems.

3.The modelling framework should reveal the generic structure of assistive technology systems and lend itself to analysis and synthesis (device specification) procedures.

4.The modelling framework should support the development of new assistive technology systems to meet particular needs.

5.The modelling framework should be able to support the process of providing assistive technology for a particular user, with the aim of avoiding device rejection and abandonment.

6.The modelling framework should give engineers and other professionals a clearer understanding of how assistive technology systems function in a social context.

1.3.1 Modelling Approaches: A Review

Real-world situations are frequently highly complex. This means that simplifying assumptions need to be made to give a model of appropriate size and complexity to analyse, programme or use in predictions. It also frequently means choosing the elements of the situation that are relevant to the particular problem for modelling and ignoring the others. This will generally give a choice of a number of different

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possible models and modelling structures depending on the aims and desired outcomes of the modelling process. Approaches in the literature to modelling assistive technology have often had different aims or a subset of the aims of the above comprehensive modelling framework. A thorough review of the literature reveals both that the development of assistive technology has only been studied by a limited number of researchers and that there are no existing modelling approaches that meet all the criteria stated above.

Although the distinction is not totally precise, there are two main approaches, based on:

•Matching the end-user to appropriate assistive technology and/or measuring the outcomes of the use of assistive technology.

•The development of a generic framework for device analysis and synthesis.

The user matching approach has a relationship to the quality of life methodologies discussed in Section 1.2. A good example of this approach is the matching person and technology model of Scherer and colleagues (for example, Scherer and Craddock 2002; Scherer and Glueckauf 2005). The model has the following three main components:

•Person, which considers the user’s personal characteristics and temperament.

•Milieu, which covers the characteristics of the settings in which assistive technology will be used.

•Technology, which considers the characteristics of the assistive technology, including design factors and funding.

As discussed in more detail in Section 1.2.4 on quality of life assessment, the matching person and technology model is used as part of an assessment process which involves completion of assessment forms. Therefore the end-user is involved in the process of fitting the model. There are a number of other modelling approaches that can be used to match (particular groups of) disabled people to assistive technology, including the following:

•SETT, which is used with disabled students and considers the four areas of student, environment, tasks and tools (Zabala 1998).

•Education Tech Points, which is based around the six ‘Tech Points’ of referral, evaluation, extended assessment, plan development, implementation and periodic review (Reed and Bowser 1998).

An associated methodology is the Siva Cost Analysis Instrument (SCAI), which is intended to assist the assistive technology professional and the end-user in estimating the costs of a particular assistive technology system and comparing the costs of different options (Andrich 2002).

The USERfit model aims to provide a structured framework for a user-centred approach to assistive technology design (Poulson and Richardson 1998). It consists of three main components: problem definition, functional specification and build and test.

The problem definition component is divided further as follows:

•Context of use, comprising environmental context, which includes a high level summary of the product and its likely users; and product environment, including training, documentation, installation, maintenance and user support for the product.

•Analysis, comprising user analysis, which identifies the stakeholders to be considered in product development and their attributes; activity analysis, covering the range of activities the product will be used for and the associated implications for product design; and product analysis, covering the functional aspects of the product listed as operational features.

Functional specification consists of the following three components:

•Product attribute matrix, which summarises the match between the emerging functional specifications and product attributes.

•Requirements summary, in which the design features identified by the user and activity analysis and their degree of match to user requirements are summarised.

•Design summary in which a more detailed summary of the product functional specifications and their operational details are given.

Build and test consists of usability evaluation, which covers plans for evaluation, objectives, methods and criteria and documentation of the match between the criteria and results.

Human activity assistive technology (HAAT) model

This model due to Cook and Hussey (2002) is an example of the approach based on developing a generic structure which can be used for device analysis, synthesis and development, but not for matching the device to the person. Cook and Hussey start from the definition of an assistive technology system as enabling a person to perform an activity in the context of a social environment with the possible aid of some assistive technology. Thus the HAAT model defines an assistive technology system through the following four components:

1.Context, which defines the social framework and the physical environment in which the human person and the assistive technology have to operate. The context is divided into the cultural context, the social context, the human setting and the physical context, with further subdivisions suggested for each of these categories.

2.Human person represents the human being at the centre of the HAAT model, who is considered to have the attributes of sensory inputs, central processing power and motor inputs. However, this rather mechanistic approach has the disadvantage of reinforcing the tendency of engineers and designers to ignore the wider aspects of human-centred design, such as aesthetics and values, which may be very important in determining whether a device is actually used and whether it actually meets users’ needs.