Page 125 -

I 94 Chapter 3 Understanding users

Using incorrect mental models to guide behavior is surprisingly common. Just
watch people at a pedestrian crossing or waiting for an elevator (lift). How many
times do they press the button? A lot of people will press it at least twice. When
asked why, a common reason given is that they think it will make the lights change
faster or ensure the elevator arrives. This seems to be another example of following
the "more is more" philosophy: it is believed that the more times you press the but-
ton, the more likely it is to result in the desired effect.
Another common example of an erroneous mental model is what people do
when the cursor freezes on their computer screen. Most people will bash away at
all manner of keys in the vain hope that this will make it work again. However, ask
them how this will help and their explanations are rather vague. The same is true
when the TV starts acting up: a typical response is to hit the top of the box repeat-
edly with a bare hand or a rolled-up newspaper. Again, ask people why and their
reasoning about how this behavior will help solve the problem is rather lacking.
The more one observes the way people interact with and behave towards inter-
active devices, the more one realizes just how strange their behavior can get-
especially when the device doesn't work properly and they don't know what to do.
Indeed, research has shown that people's mental models of the way interactive de-
vices work is poor, often being incomplete, easily confusable, based on inappropriate
analogies, and superstition (Norman, 1983). Not having appropriate mental models
available to guide their behavior is what causes people to become very frustrated-
often resulting in stereotypical "venting" behavior like those described above.
On the other hand, if people could develop better mental models of interactive
systems, they would be in a better position to know how to carry out their tasks ef-
ficiently and what to do if the system started acting up. Ideally, they should be able
to develop a mental model that matches the conceptual model developed by the
designer. But how can you help users to accomplish this? One suggestion is to edu-
cate them better. However, many people are resistant to spending much time
learning about how things work, especially if it involves reading manuals and other
documentation. An alternative proposal is to design systems to be more transpar-
ent, so that they are easier to understand. This doesn't mean literally revealing the
guts of the system (cf. the way some phone handsets-see Figure 3.9 on Color
Plate 4-and iMacs are made of transparent plastic to reveal the colorful electronic
circuitry inside), but requires developing an easy-to-understand system image (see
Chapter 2 for explanation of this term in relation to conceptual models). Specifi-
cally, this involves providing:
useful feedback in response to user input
easy-to-understand and intuitive ways of interacting with the system
In addition, it requires providing the right kind and level of information, in the
form of:
clear and easy-to-follow instructions
appropriate online help and tutorials
context-sensitive guidance for users, set at their level of experience, explaining
how to proceed when they are not sure what to do at a given stage of a task.