Chapter 4: what is the relationship between sensation and perception

binding problem

process used by brain to combine results of many sensory operations into a single percept; brain synchronizes firing patterns in different groups of neurons that have each detected different features of an object

bottom-up processing

stimulus-driven processing; perceptual analysis that emphasizes characteristics of the stimulus, rather than our concepts and expectations

binocular convergence

suggests how lines of vision from each eye converge at different angles on objects at different distances

relative size

two objects assumed to be the same size cast different-sized images on the retina, judge to be at different distances

Muller-Lyer illusion

horizontal lines with arrowheads; possibly see as 3-D images; when tow objects make the same size image on the retina and we judge one to be father away than the other, we assume the more distant one is larger

ambiguous figures

images that are capable of more than one interpretation; vase/faces; Necker cube

monocular cues

info about depth that relies on the input of just one eye

binocular cues

information taken in by both eyes that aids in depth perception

cultural influences

ponzo illusion; see top bar longer as a result of linear perspective; Pacific island of Guam with no distance convergences do not see as such

Hermann Gird

Black boxes and white lines; gray dots appear; firing of certain cells sensitive to light-dark boundaries inhibits activity of adjacent cells that would otherwise detect white lines

Gestalt psychology

Nature of perception; belief that much of perception is shaped by innate factors built into brain that see patterns, gestalts, in stimulation; from raw material of stimulation, brain forms a perceptual whole that is more than the mere sum of its sensory parts

learning based inference

Nurture of perception; Hermann von Helmholtz; view that perception is primarily shaped by learning/experience rather than by innate factors; allow observer to make inferences

Laws of perceptual grouping

Wertheimer; gestalt principles of similarity, proximity, continuity, and common fate; suggest how brains prefer to group stimulus elements together to form a percept

perceptual constancy

ability to recognize same object as remaining "constant" under different conditions; color, size, shape, etc

retinal disparity

arises from difference in perspectives of two eyes; greater disparity when looking at nearby objects -> depth information

relative motion

as you move, objects at different distances appear to move through your field of vision at a different rate

interposition

assume that closer objects will cut off our vision of more distant objects behind them

ground

backdrop against which we perceive the figure

Bower's virtual reality

ball image movies through space, reaction from infant; suggests some depth perception innate

subjective contours

boundaries that exist not in the stimulus but only in the subjective experience of the mind

feature detectors

cells in the occipital lobe's visual cortex that specialize in extracting certain features of a stimulus

top-down processing

conceptually driven processing; perceptual analysis that emphasizes the perceiver's expectations, concept memories, and other cognitive factors, rather than being driven by characteristics of the stimulus

context and expectations

ex, difficult to recognize people outside their usual setting

Gibson and Walk's visual cliff

experiment for finding origins of depth perception; babies perceive depth and associate drop-off with danger; crawling helps develop

closure

gestalt principle that identifies tendency to fill in gaps in figures and to see incomplete figures as complete; humans have a natural tendency to perceive stimuli as complete and balanced even when pieces are missing

law of continuity

gestalt principle that we prefer perceptions of connected and continuous figures to disconnected and disjointed ones; assume continuity in the personality of an individual

law of proximity

gestalt principle that we tend to group objects together when they are near each other; "you're known by the company you keep"

law of similarity

gestalt principle that we tend to group similar objects together in perceptions; "birds of a feather flock together"

law of common fate

gestalt principle that we tend to group similar objects together that share a common motion of destination; school of fish, marching band

atmospheric perspective

haze or fog makes objects in the distance look lest distinct

percept

meaningful product of perception; often an image that has been associated with concepts, memories, emotions, and motives

law of Pragnanz

minimum principle of perception; simplest organization, requiring least cognitive effort, fully developed figure; perceptual system prefers to see a fully developed Gestalt

light and shadow

objects that reflect the most light appear to be nearer than more dimly lit objects

figure

patter, or gestalt, that grabs our attention

perceptual set

readiness to detect a particular stimulus in a given context; sprinter anticipating starter's pistol; involves focused alertness for a particular stimulus in a given context

Richard Gregory

went to South Africa to study Zulu "circular culture"; are not fooled by Muller-Lyer illusion; suggests this illusion is learned

illusion

when your mind has a demonstrably incorrect perception of a stimulus patter; likely when the stimulus is unclear, info is missing, elements are combined in unusual ways, patterns are not apparent