1. Perception
Unit 4

2. Form perception
Perception is taking sensory input and giving it meaning.
Gestalt…
…whole sum is greater than the parts.
Ex.: 3 pac-man shapes arranged appear as a triangle.
Figure-ground – situation where we see either a figure-against-a- background, OR the background becomes the figure.
Ex.: the vase/profile of people

3. Cont. Grouping – we lump similar things together. Here’s how…
Proximity
Similarity
Continuity
Closure
Connectedness

4. Depth perception = the ability to gauge distance.
Visual cliff – babies will not crawl across a glass table; they can perceive depth.
Binocular cues – our eyes are 2 ½ inches apart. We see from 2 angles. (finger sausage)
Retinal disparity enables our brain to calculate distances.

5. Depth (cont.) Monocular cues – these are good for long distances.
Relative height – higher up  farther
Relative size – bigger  closer
Interposition – stacked items
Linear perspective – think RR tracks
Light & shadow – dark  close; light  far
Relative motion – fast moving  close; slow  far
Texture gradient – detailed  close

6. Big = close
Small = far

7. Taller or wider?

8. Light

10. Depth…
Size?
Shading?
Texture?
Linear perspective?

11. Motion perception & Constancy
Stroboscopic effect – series of still pics shows motion (old films)
Phi phenomenon – 2 lights flashing seems like movement back/forth
Shape constancy – tendency to expect things hold their shape
Lightness constancy – tendency to expect light to remain the same.
Color constancy – tendency to expect color to remain the same.

13. Constancy (cont.)
Size constancy – tendency to expect things to retain their size
Moon illusion – moon low on horizon looks huge due to trees/houses
Muller-Lyer illusion – two equal lines appear different lengths
Ponzo illusion – linear perspective makes “distant” items look big
Ames room – funky-shaped room fools our expectations about a room.

14. Funky dog house (expectations matter)

15. Misc.
Perceptual adaptation = our ability to adjust to changes in our sensations.
Ex.: “inversion goggles” (that skew/flip vision)…our brain corrects them
Perceptual set = what we’ve already experienced & thus expect.
Ex.: a log floating on Loch Ness is the monster!
Context matters. We expect things to be in context/normal.
Ex.: “It’s wagging its tail, what a cute little log.” (we might hear “dog”)
Ex.: curious rabbits climbing in boxes (either on floor or from ceiling)
Ex.: a 6’9” basketball player seems small beside a 7’9” player

16. Expectations…

17. Misc. (cont.) Emotions & motivations matter
Hiking up to a hill. If tired, it looks huge. If refreshed, not so big.
If motivated to see something, people likely do.
Seen in the horse/seal ambiguous image.
ESP = extra sensory perception
Idea some people can sense things beyond normal senses
½ of people believe it’s real
“Psychics” seem really good at manipulating/leading people along
Science says, nah