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Fuzzy Thinking, Usability and Older People
By Scott Milne, published 9th July 2004.
When does a person become old? Upon which birthday is a person welcomed into the set of 'older people'? The question seems preposterous, anyone can see that we grow older gradually over time, and continue to grow older still even when we are already considered 'old'. It is a matter of degree, and everyone is old to a degree. It would be helpful then, when considering usability for older people, to think in degrees and not in terms of old or not old.
Designing for Older People
It is a well known fact that our physical and cognitive abilities decline with age [1, 2]. This means that not only are older people more likely to suffer from a particular disability, they are more likely to experience a combination of different disabilities which can interact with each other to create new 'emergent' problems not experienced by those with a single disability. These emergent problems are inherently hard to predict because of the subtle conditions which create them and they will vary from one person to the next. This has led many experts in the field of Human Computer Interaction to declare that the most identifiable characteristic of the older population is its diversity; that is: the very absence of an identifiable characteristic [3]. If we cannot pin down the shared characteristics of this group then we have very little chance of producing appropriate design guidelines, except on that principle of 'designing for dynamic diversity' [3, 4]. It is no coincidence that this approach is also inclusive of all those 'non-older people' who nevertheless have particular disabilities (or combinations thereof). A 'diversity' focussed design philosophy seems to be ideal for the web and other software interfaces which are used by broad and often undefined audiences. So where does fuzzy thinking come in?
The Fuzzy Bit
'Fuzzy logic' is an alternative to traditional logic in which a statement needn't be true or false, but is instead true to a degree. More simply put, fuzzy logic refuses to deal only with black and white, 1's and 0's, insisting that: since the world is full of greyness (if you'll pardon the pun), then logic must be capable of dealing with this.
More generally, 'fuzzy thinking' is applying fuzzy logic to real world problems where traditional logic would fail (or at best would simplify the problem to the point of absurdity) [5].
Binary Logic in Web Design
A simplistic web design philosophy might state: "I, designer, will build a look and feel which cannot be adapted in any way, shape or form lest my aesthetic expression be defiled. For those who cannot appreciate this design, I will deign to create a text-only version."
This is clearly an inappropriate philosophy for a medium such as the web where even the interaction environment can't be controlled for, let alone the end users' needs, abilities and other characteristics. (Of course, designers following this binary logic still deserve more praise than designers who see only themselves: "all users will cope with my design", some kind of ghastly unary logic).
Fuzzy Thinking in Usable Web Design
The simplistic design philosophy detailed above seems akin to the binary thinking of traditional logic: "all users will cope with my design except for those who reach a threshold beyond which the design cannot be appreciated, at which point they must switch to the text-only version".
Fortunately, due to advances in browsing technology and increasing adherence to design standards, few such thresholds need exist. An obvious example is that of text size, where a visually impaired user for whom the text on a web page is too small can simply increase the size of that text until it becomes readable. Even in this simple example, fuzziness is everywhere. Firstly, default text size varies from one web site to the next, and within a web site different sizes are used for semantically different pieces of text such as headings, subheadings, paragraphs etc. Then, optimal text size varies from one user to the next depending on each person's visual ability, their browsing technology, screen resolution, room lighting etc. Optimal text sizes for any particular person will also vary from day to day depending on factors such as the extent of the previous evening's alcohol consumption. (Note: 'fuzzy thinking' in that context is something quite different, and isn't particularly recommended as a positive contribution to a serious discussion on usability). How 'simple' a browser makes it for a user to change the text size is another fuzzy variable - particularly for a user without the experience, confidence or even desire to play around with their browser settings. Finally, any browser settings changed by the user may have a different impact from one site to the next.
Fuzzy Thinking does not deny the existence of the two extremes. Indeed, any spectrum must have its two extremes. However, these extremes are more often the exception than the rule, especially in an area as fuzzy as human sensory and cognitive abilities.
Conclusion
Perhaps the greatest contribution of fuzzy thinking when applied to web design is in helping us to realise that, while there are many people at one extreme of a particular interaction problem, such as visual impairment, there are often many more who experience the same problem to a lesser extent but whose plight can be overlooked by well-meaning but uninformed designers. A fuzzy thinking approach encourages us to move beyond web design which caters for 'normal' people and 'extreme' people leading to the polarisation of design solutions as in the simplistic design philosophy above. Instead, fuzzy thinking encourages us to think inclusively, towards a design philosophy which by its very nature sees 'all there is to see' from the outset, and considers diversity not as an awkward and exceptional case to be dealt with as an afterthought, but as the very essence of the population which it serves.
References
- Salthouse, T. A. (1996). The processing-speed theory of adult age differences in cognition. Psychological Review, 103, 403-428.
- Salthouse, T. A., Babcock, R. L. & Shaw, R. J. (1991). Effects of adult age on structural and operational capacities in working memory. Psychology and Aging, 6, 118-127.
- Gregor, P., Newell, A.F. & Zajicek, M., Designing for dynamic diversity - interfaces for older people, in: ASSETS 2002 (The Fifth International ACM Conference on Assistive Technologies, 8-10 July, Edinburgh, Scotland 2002) (ed. J. A. Jacko) pp.151-156.
- Newell, A.F. & Gregor, P., Designing for extra-ordinary people and situations, CSERIAC Gateway XI(1) (2000) pp.12-13.
- Kosko, B., Fuzzy Thinking, Flamingo, 1994