Cognitive psychology

Knowing a few basic notions of cognitive psychology is useful for user-centred design. By taking an interest in users' cognitive functioning, you anticipate what could help, or on the contrary block them.

Working memory is a notion that describes the structure involved in processing the tasks in hand. The theory on this concept describes working memory as the seat of decision-making, based on the information taken into account for action. The capacity of this memory is limited, which points to the notion of mental load, which is important in UX. The aim of an effective design is in particular to limit the mental load on its user.

To begin with, it is clear that having some grounding in cognitive psychology does not replace meeting real users. In the case of tests, notions from psychology can provide hypotheses to validate. For example, you can assume, a priori, that design A will be judged simpler than design B, on the basis of the information and its presentation. User testing then comes to confirm or contradict those hypotheses. Some concepts from cognitive psychology can be used as a point evaluated by the tests.

In cognitive psychology, some research gives rise to the formulation of predictive laws: Miller's law (7 items plus or minus 2 in working memory), Hick's law (decision time increases with the number of options), Fitts's law (a target must be large and close to be easily reached).