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Posts Tagged ‘patterns’

Claims and patterns in HCI

October 27, 2011 1 comment

I gave a claims-centered talk to a small discussion group last week–including four researchers with over 100 years of combined experience in the field of human-computer interaction. The question about the difference between claims and patterns question came up, with the following distinction reached. Claims are hypothetical, intended to be debated and changed based on the context. They are smaller than patterns, and many (most!) lack the rigor that are found in established patterns libraries—but those traits also make them easier to process and change as well. Patterns purport to be the truth, meant to capture things that have been decided after a great many instantiations and studies and experiments and such. There’s typically a collection of people who work toward maintaining the library, with additions and changes to it occurring rarely and with careful deliberation.

For a discipline like HCI, in which changes in context have great influence over the way a user interface should look and act, it seems that claims often would be the better choice. Does that mean claims are good and patterns are bad? Not at all…but it does mean that great care should be exhibited in choosing which to use for a given design problem. Patterns seem well-suited for domains like web development, in which there’s an assumption that a typical individual working alone at a desktop or laptop machine is seeking to accomplish a task. By “typical”, I mean, e.g., that the person has close to 20/20 vision (perhaps corrected), cognitive skills sufficient to process a fairly complex screen of information, motor skills sufficient to use a mouse and keyboard, and some experience using a web browser. But as soon as those typical traits are violated in your target user population, or as soon as you start designing for noisy or busy or mobile situations, or when you’re seeking to do something very different with your interface, it’s necessary to question the truths—which seems to be a strength of claims.

These lessons were underscored in one of my current projects—designing work support interfaces for young people with moderate to severe cognitive disabilities. So many of the mobile interface claims just don’t hold when designing for people with cognitive disabilities: button sizes have to be bigger (sometimes with only a single “button”), the number of choices have to be limited (to two or at most three!), and single-switch scanning should redundantly be employed to communicate on-screen text. In addition, the experiences have to be tailored differently: repetition in experience and questioning is often more important than reflection, and great care must be taken in the use of appropriate symbol sets. An expert at mobile interface design would almost have to “start over”, throwing away (or, at a minimum, reconsidering) all knowledge about how to design the interface.

A lot of so-called “truth” in interface design goes away when the context changes. That doesn’t mean it’s a bad idea to capture design truths, just that they should be treated with scientific skepticism when encountered in a new design problem. Capabilities of humans can differ depending on user population characteristics, as can the situations in which an interface will be used. My current thought is to use claims in this way: making it clear in design activities that they are meant to be challenged and questioned, not taken at face value. It’s there that I think the greatest value for claims (and the distinguishing value from other knowledge capture approaches) can be realized.

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Categories: Claims Tags: , ,