Cognitive psychology is the branch of psychology concerned with how our minds process the information sent from our various senses. Most of the work from cognitive psychologists has been to quantify how efficient we are at processing this type of information – how much we can process and how quickly. More recently, however, cognitive psychologists have become interested in how the mind processes information generated from working with other humans and external artefacts such as computers.

The study of cognitive psychology as a branch of psychology was started around the same time as researchers became interested in the possibility of artificial intelligence (roughly in the mid 1950’s). Psychologists believed that the human brain was some sort of information processing machine, which was fed input from senses and stored images, thoughts etc. in memory. The discipline of cognitive psychology describes the mind as:

“ A general purpose system for processing symbols that is limited by both structural and resource limitations.”

In this context, a symbol is a pattern stored in memory which represents, or ‘points-to’ something in the external world. Various processes in the mind manipulate and transform symbols from one sort to another. The goal of cognitive psychologists is to define these processes and representations; to give an understanding of how well our mind will perform a given task.

Obviously, human–computer interaction can benefit from this work by building models of user performance and defining design guidelines which are sympathetic to the way our mind processes the information being displayed on a computer screen. Cognitive psychology also offers the possibility of building user models – essentially computer programs which react the same way to certain stimuli as humans. These models can be used to test an interface and predict the types of problems users could experience. Cognitive psychology can also be used after an interface has been constructed to give insight into why users are experiencing problems with that interface.

In a future unit, you will be shown different models of how the brain processes its inputs. In this unit, however, we are primarily concerned with how humans process visual information. We will investigate how our minds process visual information and how this processing can be exploited to improve interface design. You will also discover that our eye is a lot more complex than a simple camera, and that our minds often “embellish” the images received from the eye.