The psychology of design: Perception

1. The psychology of design: Perception CS774 Human-Computer Interaction Spring 2004

2. See and point Little learning Good for tyros Need to organize clutter Finding and recognizing controls can be slow Compromise - progressive disclosure, key stroke options Remember and type Much learning Good for experts Less clutter, more elegant Habitual actions fast Knowledge in the Head vs Knowledge in the World CS774 Spring 2004

3. Prelim: Learning • Putting knowledge in the head • Piaget • Accomodation - form new frames, scripts (schemas) • Assimilation - fill in existing schemas • Example - learning vi after emacs • Example - learning Powerpoint after C++ • Norman • Habituation - taking action sequences from conscious thought to automatic thought CS774 Spring 2004

4. Dog using Photoshop? • Interface can’t substitute for task KIH • Mind must be primed to be ready to learn CS774 Spring 2004

5. Gulf of Evaluation • User needs complete, timely and clear feedback • Timely - otherwise • Frustrating (3/30 second rules) • Confusing (short term memory - what was I doing?) • Clear • What happened? • User needs to properly perceive state of system CS774 Spring 2004

6. Perception • Norman’s three steps for Evaluation • Perceive the state of the interface • Interpret what it means • Evaluate the meaning as progress towards goal • Issue of the day - what do we perceive? • Levels of perception • Raw level - eyes, ears as energy transducers - what signals? • Preattentive level - first level of signal processing • Attentive level - when we pay attention CS774 Spring 2004

7. Issues in raw perceptual data • Resolution • The retina, cones and rods, fovea • Screen resolution, acuity • Color • Number of colors • Motion • Flicker • Rods vs. cones, peripheral vision • Bubble gum CS774 Spring 2004

8. Can you see it? • Count the Fs • Only once, first time through FINISHED FILES ARE THE RE- SULT OF YEARS OF SCIENTIF- IC STUDY COMBINED WITH THE EXPERIENCE OF YEARS. CS774 Spring 2004

9. Results? • Three or six Fs? • Preattentive processes • Involuntary, unconscious, continual • The Fs are processed at some level • Attentive processes • Semi-voluntary, conscious CS774 Spring 2004

10. The world is our construction • We construct the world from our senses • Sensory inputs (eyes, ears, balance) encode information from the world • Information is partial - too few equations to reconstruct the world accurately • We add rules/heuristics to perception to “flesh out” our perceptions CS774 Spring 2004

11. Visual Illusions and Visual Intelligence • Donald Hoffman, Visual Intelligence • http://aris.ss.uci.edu/cogsci/personnel/hoffman/hoffman.html (try a google search) • Illusions • My thesis question CS774 Spring 2004

12. Moral • How the user perceives your interface is influenced by … • Raw perceptual issues - color, resolution, etc. • Visual intelligence - perceptual rules for reconstructing the world • Context, adaptation, many things. • Moral - hire a graphics designer! CS774 Spring 2004

13. Problem of attention • Why did the instructor run into the door? • Habituated to ordinary doors, not attending to pad CS774 Spring 2004

14. Errors from misattention • Controlled flight into terrain • 1972 Everglades crash • Three crew members ignored altitude warnings trying to fix a landing gear light • Hitting the (virtual) 747 • Question - when to remove heads up display? • At landing decision point CS774 Spring 2004

15. Problem of attention • Human mind • Subconscious processes • Conscious process • Conscious process is the “executive” • Only one - what if we had many “conscious” minds? • Locus of attention • Conscious mind is attending to one thing CS774 Spring 2004

16. And this means ... • Designing around the users attention • What level of task is in their head? • What are they attending to? • Are you requiring a diversion of attention? • How do you signal for the user’s attention? • Sound • Motion • Dialog box popping up at cursor location (wherever they’re looking) CS774 Spring 2004