Transcript
Chapter 6 LECTURE NOTES: Perception
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 your nose in line of vision
Cocktail Party Effect: (example of selective attention) ability to focus only one voice in a crowd.
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 perceived 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 meaningful 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, light-dark contrast)
To process forms, use grouping: rules the mind follows to organize stimuli into logical groups
Grouped into Proximity, Similarity, Continuity, Closure, Connectedness
Depth perception: ability to see objects in 3D even though image sensed by retina are 2 dimensional; allows distance judgment; partly innate
Visual cliff: laboratory device for testing depth perception in infants/animals
Gibson and Walker placed 6-14 month old infants on edge of a visual cliff (table half glass, half wood), making the appearance of a drop-off; mothers then tried to convince infant to crawl past the normal part of the table onto glass; most refused, indicating perception of depth
Binocular cues: depth cues that depend on both eyes
Eyes apart, slightly different images, brain sees difference
Retinal disparity: binocular cue in which the greater the difference between images, the closer the object
Convergence: binocular cue in which the more the eyes turns inward, the closer the object appears
Monocular cues: distance cues that are available to either eye, (relative size, interposition, relative clarity, texture gradient, relative height, relative motion, linear perspective, relative brightness)
Brain computes motion based partly on assumption that objects moving away are 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))
Interpretation
Previously blind patients often can't recognize objects familiar by touch only
Sensory restriction like allowing only diffuse, unpatterned light through; affects only at infancy, suggesting critical period for development
Perceptual adaptation: ability for our vision to adjust to artificial displacement; given goggles that shift vision 30 degrees to left, humans learn to adjust actions 30 degrees to left (remember the quarterback)
Roger Sperry surgically turned eyes of animals; found out fish, frogs, salamanders (Note: reptiles) CAN'T ADJUST while kittens, monkeys, and humans (Note: mammals) did ADAPT
Experiences, assumptions, and expectations give us a Perceptual set: mental set-up to perceive one thing and not another; ufo-looking objects that are really clouds; because we can't resist finding a pattern on unpatterned stimuli
Much of our perception comes not just from world "out there", but also from behind the eyes and between the ears.
ESP
50% of Americans believe in extrasensory perception (ESP): claim perception occurring without sensory input
Three varieties of ESP: Telepathy (sensing or reading thoughts),
Clairvoyance (perceiving an event unfolding),
Precognition (seeing future)
Parapsychology: study of paranormal phenomena (profession called Parapsychologists)
Vague predictions can later be interpreted to match events; Nostradamus claimed his prophecies could not be interpreted till after the event
After many experiments, there has never been a reproducible ESP phenomenon or individual who can convincingly demonstrate psychic ability
