Interview (mp3, 24:26, 22.19MB, Dec 2006)
Mental models are an important concept for HCI but one that has remained obscure. Namahn invites Professor Stephen Payne to talk about his research on how people's beliefs about the devices they use affect the way they interact with them and what implications this might have for designers.
"People are promiscuous inference makers," claims Payne, "and they'll make inferences about the device they're using that will affect their behaviour." As an example he cites research done in the 1980s in America on how people perceived their home heating controllers or thermostats. The correct model of the thermostat is that it controls whether a furnace is on or off; it will be on until the ambient temperature has met the temperature set in the thermostat. But some research subjects reasoned that the higher they set the thermostat, the more work the furnace would do. Their mental construct of the thermostat was that it was a valve instead of a switch and so they wasted oil. Were the designs of the thermostat to blame? Could the representation of the device as a dial have led users to make wrong conclusions?
Namahn notes that as designers we're interested in how to impact a design so that the mental model that the user forms is an appropriate one. Payne offers a variety of factors to consider, some of which are counterintuitive, and stresses the importance of employing appropriate analogies and words to describe tasks. For example, in early studies with the computer researchers found that users developed a more efficient use of the "copy/paste" commands when the words were changed to "store/recall". Payne suggests that if software designers are attuned to the fact that users will build analogical structures and reason about devices through analogy it will help them in the design process.