1. UGS 302 Usability and User-Centered Design
Day 3

2. Objectives After this class you will be able to (it is my hope!):
Describe some eye physiology
Explain how the visual system works (somewhat)
Identify visual cues to depth
Be able to describe what it means to say “perception is not the simple sum of sensations.”

3. Whole point . . .
Let’s design systems to fit people instead of the other way around.

4. Human Information Processing
How do human beings take in and process information?
Sensory psychology – how humans transform physical energy (e.g., light and sound waves) into sensory signals to and in the brain.
Perceptual psychology – how humans interpret these sensory signals as perceptions.
Cognitive psychology – how humans think about these perceptions, and previous experiences, and their own mental creations, and . . .
Psycholinguistics – The psychology of language -- what goes on between the time I have a thought and you have the same (or similar!) thought, whether I say it or write it.

5. Ear Physiology

6. Basilar membrane

7. Eye Physiology

8. Eye Muscles

9. Visual Field

10. Retinal Physiology

11. Distribution of Rods and Cones

12. Visible Spectrum

13. Visual Sensitivity

14. Neural Pathways

15. Aftereffect

16. Ambiguous Figure

17. Sensation/Perception
POINT: Perceptions are made up of more than just a collection of sensations!
OTHER things influence our perceptions, e.g.,
Our experiences
Our biases
The context
Our current emotional state
Etc.
So, what does that have to say about designing human-computer interfaces???

18. Perceptual Psy – Color Vision
Color perception – 3 types of cones (RGB)

19. Perceptual Psy -- Depth
Different visual cues to depth
Oculomotor vs. Visual
Oculomotor – Lens accommodation and extraocular muscle convergence are “read” by the brain
Visual: Binocular vs. Monocular
Binocular – Stereopsis (retinal disparity)
Monocular (next screen)
Static
Motion parallax

20. More Depth Cues Monocular Static Motion parallax Interposition Size
Perspective
Linear perspective
Texture gradient
Aerial perspective
Shading
Motion parallax

21. Monocular Cues -- Interposition

22. Monocular Cues -- Size

25. Monocular Cues – Linear Perspective

26. Monocular Cues – Texture Gradient

27. greener on the other side of the fence!!!
Sooooo . . .
The grass really IS
greener on the other side of the fence!!!

28. Monocular Cues – Aerial Perspective

29. Monocular Cues -- Shading

30. Monocular Cues – Motion Parallax

31. More visual perception
Illusions – and what they tell us about vision
Ponzo illusion
Muller-Lyer illusion

32. Ponzo Illusion

33. Muller-Lyer Illusion

34. Homework Finish reading The Invisible Gorilla.
Start reading The Design of Everyday Things
For Thursday -- Bring to class picture or verbal description of good and poor designs. NOT web sites. Physical objects.