Selective Attention

�     Selective attention: focusing only on one thing at a time; focused awareness only on limited aspect of all that is capable of experiencing; you aren’t aware of nose in line of vision

�     Cocktail Party Effect: (example of selective attention) ability to focus only on one voice in a huge crowd

�     Unnoticed stimuli has effect: women who had listened to tunes previously played to them while unnoticed preferred it later on

Perceptual Illusions

�     Visual capture: phenomenon when a conflict occurs between vision and another sense, vision dominates; vision captures other senses (overrides)

�     in theaters, sound comes from behind (projector), yet perceive as from screen

�     Perceiving voice coming from ventriloquist’s dummy

Perceptual Organization

�     Humans organize clusters of sensation into gestalt: organized “whole”; human tendency to order pieces of info into a meaning picture

�     First perceptual task: to perceive figure (object) as  distinct from  ground (background)

�     Figure-ground: organization of visual field into the figure(s) that stand out from the ground

�     Next, organize figure into meaningful form (color, movement, like-dark contrast)

�     To process forms, use grouping: rules mind follows to organize stimuli into logical groups

�     Grouped into  Proximity,  Similarity, Continuity, Closure, Connectedness (visuals on page 185, figure 6.5 and definition on page 186 of 5 edition)

�     Depth perception: ability to see objects in 3D even though image sensed by retina are 2D; allows distance judgment;

partly innate (born with)

�     Gibson and Walker placed 6-14 months old infants on edge of a visual cliff (table half glass, half wood), making the appearance of a drop-off; Mothers then tries to convince infant to crawl pass the normal part of the table onto glass; most refused, indicating perception of depth

�     Visual cliff: laboratory device for testing depth perception in infants/animals

�     Binocular cues: depth cues that depend on both eyes

�     Eyes apart, slightly different images, brain sees difference –retinal disparity: bi cue in which the greater the difference between images, the closer the object

�     Convergence: bi cue in which the more the eyes turns inward, the closer the object

�     Monocular cues: distance cue that are available to either eye

�     Examples: relative size, interposition,  relative clarity,  texture gradient, relative height, relative motion, linear perspective, relative brightness  (definitions on pages 188-189 of 5 edition)

�     Brain computes motion base partly on assumption that objects moving away is shrinking & vise versa

�     Brain reads rapid series of slightly different images as movement; phenomenon called stroboscopic movement

�     Another illusion of movement is phi phenomenon: perception of movement when lights blink one after the other; the lighted arrow signs on the back of parked construction trucks

�     Perceptual constancy: perception that objects are not changing even under different lighting; allowing identification regardless of angle of view [a door is a door even at 45 degree (shape constancy) angle or 20 feet away(size constancy)]

�     Even at same size, linear perspective causes one to see one object bigger (page 191 figure 6.13a)