1. Human Factors Psychology Aside on Affordances PSY-4340/PSY-5340, Dr. William Langston, MTSU

2. Example 1 Consider this example: Consider this example: (Downloaded from http://sunburn.stanford. edu/~nick/compdocs/, click on Practical HI Examples.pdf)

3. Example 2 Someone sent me a list of things like this: Someone sent me a list of things like this: Tesco’s Tiramisu Dessert: Tesco’s Tiramisu Dessert: Do not turn upside down (printed on the bottom of the box). Do not turn upside down (printed on the bottom of the box). Unrelated, but my favorite: Unrelated, but my favorite: Japanese food processor: Japanese food processor: Not to be used for the other use. Not to be used for the other use.

4. Example 3 You’ve seen this one before. (Downloaded from http://www.baddesign s.com) http://www.baddesign s.com

5. Examples 4 & 5 Two more from the same source. Two more from the same source. (Downloaded from http://ww.baddesigns. com) (Downloaded from http://ww.baddesigns. com)

6. Affordances What do all of these have in common? I would argue that they all afford an action that isn’t intended. What do all of these have in common? I would argue that they all afford an action that isn’t intended. Gibson (e.g., 1950) proposed a theory of direct perception. A caricature: Gibson (e.g., 1950) proposed a theory of direct perception. A caricature: Light is structured into an ambient optic array. Each point in this array carries potential information. Light is structured into an ambient optic array. Each point in this array carries potential information. This information takes the form of affordances if a particular organism happens to be there to pick it up. This information takes the form of affordances if a particular organism happens to be there to pick it up. Information pick-up is direct. Information pick-up is direct.

7. Affordances Perceiving affordances: Perceiving affordances: If I’m looking for a place to sit, sit-on-ableness will be perceived by me in objects that have that property. If I need something to throw, that will be afforded. If I’m looking for a place to sit, sit-on-ableness will be perceived by me in objects that have that property. If I need something to throw, that will be afforded. It’s kind of like an automatic process in that there isn’t conscious mediation. The affordance is just there. It’s kind of like an automatic process in that there isn’t conscious mediation. The affordance is just there.

8. Affordances Evidence: Evidence: Warren (1984) had people look at various configurations of stairs to rate climbability. Warren (1984) had people look at various configurations of stairs to rate climbability. There’s an optimal configuration for minimum energy expenditure, people preferred stairs that fit this configuration. There’s an optimal configuration for minimum energy expenditure, people preferred stairs that fit this configuration. People could accurately perceive climbability (based on a biomechanical model) from looking at the stairs. People could accurately perceive climbability (based on a biomechanical model) from looking at the stairs.

9. Affordances The implication: The implication: When people are interacting with a machine/device, what it affords will have a big impact on what they do. When people are interacting with a machine/device, what it affords will have a big impact on what they do. Our examples: Our examples: A pull handle affords pulling, not pushing. A pull handle affords pulling, not pushing. A label affords reading. (I know it’s a stretch.) A label affords reading. (I know it’s a stretch.) A urinal shaped device affords pee-in-ableness. A urinal shaped device affords pee-in-ableness. A drawer handle affords pulling. A drawer handle affords pulling. A path affords walking (even if it’s not explicit). A path affords walking (even if it’s not explicit).

10. Affordances Why now? Why now? In the context of controls, I think there are important relations between design and affordances. In the context of controls, I think there are important relations between design and affordances. Things you push should look like things to push, etc. (watch me work a new shower). Things you push should look like things to push, etc. (watch me work a new shower). There could be a high level interaction. If my goal is to turn it down, a control that affords pull-down-ableness is more likely to hit me than an arbitrary control. There could be a high level interaction. If my goal is to turn it down, a control that affords pull-down-ableness is more likely to hit me than an arbitrary control. Remember that affordances are a function of the user’s body. If something is supposed to afford a particular action, it needs to be designed for all possible users. Remember that affordances are a function of the user’s body. If something is supposed to afford a particular action, it needs to be designed for all possible users. I’m sure we could do more. I’m sure we could do more.

11. References Warren, W. H., Jr. (1984). Perceiving affordances: Visual guidance of stair climbing. Journal of Experimental Psychology: Human Perception and Performance, 10, 683-703.