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
