1. Sensation and Perception
Module 19 Visual Organization and Interpretation

2. Gestalt
“whole”: human tendency to see patterns and form info into sets/groups/patterns/wholes
Fundamental truth: brain does more than register info about the world

3. Form Perception Figure-Ground:
1st have to observe the figure, which is then distinct from its surroundings

4. Grouping Forming coherent “groups”/wholes
Looking for meaningful forms…color, movement, light
Proximity
Continuity
Closure

5. Depth Perception
To see objects in three dimension even when we are actually only seeing two dimensional cues **judges distance
Innate
Visual Cliff

6. Binocular Cues
Two eyes are better for judging distance
Retinal disparity: comparing images from retinas, brain computes the distance
The greater the difference between the two images, the closer the object is to the viewer.
The more alike the two images, the further away the object is perceived.
Is most effective when the item is quite close to the person
Example: hold a pencil just in front of your nose and close one eye, then the other. The pencil should move showing the disparity. Now focus on something far away and do the same. It should not move very much showing less disparity perceived

7. Binocular Depth Cues: Finger Sausage
Hold your two index fingers about 5 inches in front of your eyes, with their tips half an inch apart. Now look beyond them and note the weird result. Move your fingers out farther and the retinal disparity—and the finger sausage—will shrink.

8. Monocular Cues Depth cues that require the use of only one eye
Monocular depth cues include:
relative size
relative motion
interposition
relative height
texture gradient
relative clarity
linear perspective.

9. Monocular Cues : Relative Size
Using the perceived size of a familiar object to determine depth
The larger the object appears, the closer the object is to the viewer
The smaller the object appears, the farther away it is to the viewer.

10. Monocular Cues: Interposition
Method of determining depth by noting that closer objects partially obstruct/block the more distant objects
Also called “overlap”

11. Monocular Cues: Relative Clarity
Perceive hazy objects as further away than those that are sharper/clearer

12. Monocular Cues: Texture Gradient
Change from coarse, distinct texture to fine, indistinct to indicate distance

13. Monocular Cues: Relative Height
Object higher in our visual field of vision as further away
Contributes to the illusion that vertical dimensions are longer than identical horizontal dimensions
You know that the trees and houses are farther away than the lake because they are higher up in the drawing than the lake is.

14. Monocular Cues: Relative Motion
Or motion parallax. As we move objects that are actually stable may appear to move
In this example, the passenger is moving past a stable world. If she fixes her gaze on the bridge, objects behind it will appear to move forward. The farther away the object is, the more slowly it will appear to move. Objects in front of the fixation point appear to move backward.

15. Monocular Cues: Linear Perspective
Parallel lines appear to converge in distance

16. Monocular Cues: Light and Shadow
Nearby objects reflect more light so dimmer objects appear to be further away

17. Motion Perception
Stroboscopic motion: how animation works. Slightly varied pictures flashed at a high speed
Phi phenomenon: perceived motion, lights blink on and off in quick succession

18. Perceptual Constancy
Perception where objects do not change even as illumination or retinal images change (top-down)
Color and Brightness Constancies
Color is derived from its context
** Comparisons govern our perceptions

19. Size and Shape Consistency
Shape appears to change depending on our viewpoint
Shape Consistency: even when viewed in distance still consistent (the moon)
Ponzo Illusion
Applies to other senses
McGurk Effect

20. Sensory Deprivation and Restored Vision
Born without sight and later gain it…can they recognize things they know by touch only?
Could distinguish figure and ground
Sense colors, suggests we are born with abilities
Could not recognize by vision things they knew by touch

21. Perceptual Adaptation
Ability to adjust to changes in out senses.
New glasses…blurry at first, will adjust