Depth Perception

Agenda Bell Ringer: How are inattentional blindness and change blindness related? 2. Lecture: Depth Perception (20) Illusions will follow - Cross-Eyed Experiment, Finger Experiment (5) - Kuleshov Effect (10) 3. Brain games: Perception. (10) 3. Matching Analysis, Sensation and Perception (15) - After Lunch 4. Goggle Experiment (if time)

Bell Ringer Is there a pattern? Why or why not?

Depth Perception The ability to see things in 3-D Allows us to judge distance

Visual Cliff: Eleanor Gibson and Richard Walk 1960 suggested that human infants (crawling age) have depth perception. http://www.youtube.com/watch?v=p6cqNhHrMJA&safety_mode=true&persist_safety_mode=1&safe=active

http://www. youtube. com/watch http://www.youtube.com/watch?v=p6cqNhHrMJA&safety_mode=true&persist_safety_mode=1&safe=active

How do we transform two differing 2D retinal images into a single 3D image? Monocular cues Available to each eye separately Used by artists Binocular cues Require both eyes

Binocular Cues – Retinal Disparity images from the two eyes differ closer the object, the larger the disparity

Retinal disparity: Images from the two eyes differ Retinal disparity: Images from the two eyes differ. Try looking at your two index fingers when pointing them towards each other half an inch apart and about 5 inches directly in front of your eyes. You will see a “finger sausage” as shown in the inset.

Binocular Cues Convergence Neuromuscular cue Two eyes move inward for near objects

Convergence: When two eyes move inward (towards the nose) to see near objects and outward (away from the nose) to see faraway objects.

Monocular Cues Relative Size – smaller image more distant

Relative Size

Monocular Cues – Interposition – if one object partially blocks another, we perceive it as closer.

Interposition

Monocular Cues Relative clarity – hazy objects are seen as more distant.

Relative Clarity Because light from distant objects passes through more light than closer objects, we perceive hazy objects to be farther away than those objects that appear sharp and clear

Monocular Cues Texture gradient – course objects appear closer & fine more distant

Texture Gradient

Monocular Cues Relative height – objects higher in our field of vision appear farther away; vertical longer than horizontal.

Relative Height

Relative Height

Monocular Cues Relative motion – closer objects seem to move faster.

Objects closer to a fixation point move faster and in opposing direction to those objects that are farther away from a fixation point, moving slower and in the same direction.

Monocular Cues Linear Perspective – parallel lines appear to converge w/distance.

Linear Perspective

Monocular Cues Light & shadow (relative brightness) – closer objects appear brighter; shading produces depth.

Light & Shadow

Motion Perception

Motion Perception: Objects traveling towards us grow in size and those moving away shrink in size. The same is true when the observer moves to or from an object. OBJECTIVE 8| State the basic assumption we make in our perceptions of motion, and explain how these perceptions can be deceiving.

Phi Phenomenon An illusion of movement created when two or more adjacent lights blink on and off in succession. Marquees or holiday lights

Phi Phenomenon One light jumping from one point to another: Illusion of motion. Two lights flashing one after the other.

Stroboscopic movement The brain will interpret a rapid series of slightly varying images as continuous movement.

Perceptual Constancy Perceiving objects as unchanging even as illumination & retinal images change.

Perceptual Constancy Size – car driving away appear smaller but doesn’t shrink

Perceptual Constancy Shape – look at a dinner plate from various angles Lightness – shirt looks different in different light

Perceptual Constancy – Ponzo Illusion The distant monster and top red bar appear bigger because of distance cues.

Perceptual Constancy

Perceptual Constancy

Perceptual Constancy

Size-Distance Relationship Both girls in the room are of similar height. However, we perceive them to be of different heights as they stand in the two corners of the room.

The color and brightness of square A and B are the same. Lightness Constancy OBJECTIVE 11| Discuss lightness constancy and its similarity to color constancy. Courtesy Edward Adelson The color and brightness of square A and B are the same.

Theories about how we see and what we see: 1. Template matching: our brains have a template for everything we need to know and we match what we see to the templates

2. Prototype matching: we see what the best example of something is and see if they are close enough to match

3. Feature analysis: we break down a feature into parts and analyze what it is

Kuleshov Effect https://www.youtube.com/watch?v=i8akNCJQz-0