Posts from: March, 2008

HCI Week 6: Affordances discussion

Monday, March 10th, 2008

affordances-discussion.png

This week’s class was a discussion of Gibson’s theory of Affordances based on the results of the practical exercise. Each group found three examples of affordances in products. As a group, we first looked at a still photograph of a product and discussed what it would afford for us and how we could see this from the picture. We then watched a video clip of the product in use and discussed whether we had interpreted the affordances of the product correctly and whether there were other affordances we had not considered.

Some interesting points that came up:

  • Designing to hide affordances, the locket, hidden doors.
  • Relation between affordances and knowledge of conventions. For example, red & blue color coding of faucet handles, use of an arrow on the medicine bottle lid.
  • When to use the physical form to convey an affordance and when to rely on text. For example, the labelling of the days on the medicine dispenser.
  • How does a product afford a range of levels of skill in the interaction. For example, the foosball table has relatively constrained and easy to interpret controls for a beginner (random twirling), but also affords refined interactions for a skilled player (deflecting off the wall).
  • Even a simple product such as a table affords a wide range of activities. For example, sitting down to work at, dropping a coat on, leaving reminders on, eating a meal at, hiding under or even dancing on.
  • It is also important to consider the whole posture of the body when thinking about the affordances. For example, an adjustable chair is much easier to adjust the height of when you are sitting in it than when you just operate the levers.

Do you have others that I have forgotten about?

HCI Week 5: Affordances

Monday, March 3rd, 2008

Opening a fire hose cabinet

Today’s lecture covered the theory of Affordances. This theory originates from the field of Ecological Psychology and the work of J.J. Gibson. It is best known in HCI circles through Norman’s book ‘The Design of Everyday Things.’ According to Gibson, affordances are:

“The affordances of the environment are what it offers the animal, what it provides or furnishes, either for good or ill” (Gibson, p.127)

An important aspect of the idea is that an affordance describes a potential for action in the environment in relation to a person or animal. This has proven to be a very popular concept in design, perhaps because it deals with everyday aspects of perception and interaction and relates the usability of products to their physical form (in relation to a user) in a fairly straight-forward way.

Critical Questions

  • The notion of affordances has been used in subtly different ways by different authors.
  • Confusion betwen ‘Affordance’, ‘Convention’, and ‘Constraint’.
  • Can we really talk about screen-based buttons affording clicking?

Practical Task

Your task for this week is to collect examples of affordances. In groups, see if you can find and shoot pictures and video of products that suggest the right (or wrong) actions in comparison to what they actually afford you. You should take a picture of the product by itself, and then a video of the product and action. Each group should find three examples.

Send me your examples by Friday and I will prepare a combined presentation, which we will use for a discussion in class.

For the discussion next week, discuss within your group why some things work and others are misleading.

Slides

Lecture slides are available

Readings

There are three readings for the topic of affordances. Copies were handed out in class.

  • Norman, D.A., 1990. Chapter 4 “The design of everyday things” 1st ed., New York: Doubleday.
  • Gibson, J.J., 1986. Chapter 4 “The Ecological Approach To Visual Perception” 1st ed., Lawrence Erlbaum.
  • Gaver, W.W., 1991. Technology Affordances. In Conference on human factors in computing systems: Reaching through technology. New Orleans, Louisiana, United States: ACM Press, p. 79-84.

Web Resources

  • A well written page that focuses on the differences between Norman’s use of ‘affordances’ and the original Gibsonian formulation.
  • A page from Norman that clarifies his position on affordances as focussing on ‘perceived affordances‘.