Guest posts, Innovation

Affordances, usability and tea pots

Acknowledgements

Karl Luke is an eLearning Technologist at Cardiff University. He is currently studying for an MSc in Education, Technology and Society with support from the Department of Anaesthetics, Intensive Care and Pain Medicine. The following blog entry has been formulated by concepts introduced on the MSc programme and explores their implications in the context of working within a clinical/academic department.

Affordances, usability and tea pots

KL1

Have you ever stood on a chair to change a light bulb? Maybe used a tea pot to house a plant? Or used a shoe to hold a bottle of wine? What these three examples have in common is an illustration that sometimes an object – or artefact – can be used in ways that the original developer or designer had never intended or foreseen. Such unconventional uses of artefacts are grounded in a complex intertwining between the properties of the object and the person acting on these properties; including their culture, prior knowledge or expectations/desires. These issues are examined within the concept of affordances which has gained much attention and debate within the field of Human Computer Interaction (HCI) and educational circles.

Affordances

The term affordance was first coined by the psychologist James J. Gibson (1979), who claimed that affordances are properties of the environment, relative to the behaviour of a specific animal. Building on Gibson (1979), and later Norman (1988), Gaver (1991) proposes that affordances of an object or environment are independent of perception and notes the effects of culture, experience and learning on perception. Gaver developed a framework, containing four domains, which separate affordances from the perceptual information that specifies affordances (Figure 1).

KL2

Figure 1: Graver’s affordance model

At a basic level, Gaver argues that when affordances are perceptible, they offer a direct link between perception and action. Conversely, when affordances are hidden or false, they can lead to mistakes and misunderstandings.

For more on Affordances. a quick visit to Wikipedia will gives a nice introduction to some of the underlying themes.

Why does this matter?

Viewing affordances allows us to distinguish between the utility/usefulness and the usability of an object (see MCGRENERE & HO for more information).

Whether we are designing a medical device, an eLearning package or interactive clinical guidelines, we should strive to design for both usefulness and usability. Creating affordances (action possibilities in the design) makes the object useable, but provision should also be made in improving usability by designing clear information in the object design that specifies the affordances. For example, perceptual information could be creating shadows on website buttons to afford clickability, or transmitting an error sound if a wrong input is inserted into a medical device.

Karl Luke

References

GAVER, W. W. Technology affordances. 1991. Proceedings of the SIGCHI conference on Human factors in computing systems. ACM, 79-84.

GIBSON, J. J. 1979. The Ecological Approach to Visual Perception, Boston, Houghton Mifflin.

NORMAN, D. A. 1988. The psychology of everyday things. New York: Basic books.

MCGRENERE, J. & HO, W. 2000. Affordances: Clarifying and evolving a concept.  Graphics Interface. 179-186.