It is the term used to describe a situation in which an item does not perform as intended

'Affordance' is a term most designers will have come across at some stage of their studies and careers. Don Norman introduced this term to the design community.

Despite Don Norman’s best efforts, the underlying meaning of the term is sometimes misunderstood.

How to define 'Affordance'

Don Norman first mentioned affordances in the context of design in The Design of Everyday Things (1988). Norman borrowed the term and concept from the world of James J. Gibson (1977; 1979), a prominent perceptual psychologist, but modified the meaning slightly to make it more appropriate for use by designers. Gibson originally used the term to describe "...the actionable properties between the world and an actor [user]" (Norman, Affordances and Design).

Gibson's definition essentially identifies the powerful relationship between man and things. Whether through experience or some innate ability (we will leave this debate for another day), we are capable of assessing objects according to their perceptible properties. These interpretations allow us to both determine an object's possible uses and analyse how they might help us achieve our aims and objectives. For example, just by looking at a glass we can determine that the object affords holding liquid, so we can quench our thirst. Some affordances are less obvious, and many yet to be realised, but with objects in the real, physical world, there is a natural and direct relationship between the perceptible qualities of tangible things and what we can do with them.

The Evolution of "Affordances"

In design, we cannot rely on this natural relationship. Aside from touchscreens, interactive elements in screen-based interfaces have affordances that exist in the virtual world alone, and the means of interaction are almost exclusive to this domain. Norman referred to the affordances found in screen-based interfaces as 'perceived', on the grounds that users form and develop notions of what they can do according to conventions, constraints, and visual, auditory, and sometimes haptic feedback.

Norman's distinction between real and perceived affordances is an important one for designers, especially those involved in the development of graphical user interfaces. While we have tacit knowledge of how the perceptible characteristics of physical objects will be interpreted, the design of graphical elements requires an understanding of what the user assumes or perceives will occur as a result of their interaction(s).

Perceived Affordances in Graphical User Interfaces

Traditionally, perceived affordances are based on domain-specific conventions and consistency, but in the last ten to twenty years, and especially with the evolution of touchscreens, designers have been taking inspiration from real affordances to allow the application of knowledge from the real-world to the virtual world. Users are now able to touch (e.g. Apple products), shake (e.g. Nintendo Wii controllers), blow (e.g. the Nintendo DS), swipe (e.g. e-Readers), and rotate (e.g. computer controllers) objects to influence events in the virtual world in a way that match the corresponding activities in the real-world.

The use of real-world affordances as inspiration in the design of products in human-computer interaction may present the possibility of a smooth passage from the physical to the virtual world. However, it also has the potential to influence the user negatively; especially, if the required behaviours are similar but the resulting events are unpredictable, or the necessary actions inaccurately reflect those activities we would carry out in the physical world.

Whichever approach designers adopt, their users must be able to develop an accurate view of the interface, so they can instantly and unconsciously predict the effect(s) of their actions to achieve as stable and predictable a relationship as that found between man and things in the real-world.

References & Where to Learn More

Header Image: Author/Copyright holder: Dorian Taylor. Copyright terms and licence: All rights reserved. Img