Week 2: Perception and Behaviour


Learning Outcomes


  • The psychology and physiology of perception profoundly affects the design of good user interfaces
  • By going back to perceptual principles, we can ensure that key elements and information are noticed
  • We can use affordances to make interfaces more intuitive


  • Affordance (concept)
  • Just noticeable differences (concept)
  • Key concepts of signal detection theory
  • Colour blindness: what is it, what are common types
  • Key auditory thresholds


  • Assess an interface for aspects that could be difficult to perceive for users
  • Determine affordances of physical and computer interfaces

Preparing for the Lecture

In order to get an overview of the variety of aspects that need to be taken into account when looking at perception, have a look at the different user capabilities as described by the Inclusive Design Toolkit.

Next, look at the core papers and readings. All materials are for all students – if some are highlighted for HCI or Design Informatics students, that’s because they reinforce what these students are being taught in their other courses. If you need to be economical with your time, read the textbook, followed by the core paper.

We will also look in detail at Signal Detection Theory (slides: Week2SDTPerception) – what does it take to perceive a signal (auditory / visual / tactile information) that is part of a user interface?

Here is a short podcast explaining why Signal Detection Theory matters [2 minutes, 2.3MB, mp3]

Core Paper and Readings

Textbook chapter: Chapter 3

The core paper for this week is on affordances – from the Interaction Design Encyclopaedia, by Victor Kaptelinin.

For the Design Informatics students in particular, I recommend working through the Inclusive Design toolkit web page. The toolkit outlines the different abilities that people have, and how designers can accommodate them. You may be put off by the design of the web page – it’s far from showy. Why is that the case?

For the HCI students in particular, I recommend having a look at a more in-depth description of the cognitive processing that is behind perception. A great resource for that are these animations of the pathways and mechanisms for hearing and vision. This page on the measurement of sound highlights very well the difference between physics (the actual sound waves, frequency and amplitude) and the resulting percept (loudness).