form perception 1/2

what’s the purpose of gestalts principles?

to describe how we organize visual input

figure-ground segregation

the ability to distinguish an object from its background

proximity

looking and grouping elements that are close together in space

closure

the tendency to fill in gaps in a contour to perceive a whole object

similarity

the tendency to group elements because they are physically similar

continuity

the ability to see a simple, continuous form rather than a combination of awkward forms

common fate

the tendency to group together elements that change in the same ways

top-down processing

when object recognition is guided by your own beliefs or expectations

what is priming?

when you provide an explanation to participants, this leads to faster recognition/reading time = more efficient

bottom-up processing

when object recognition is guided by the features that are present in the stimulus

bi-directional activation

when object recognition is guided by both types of processing (object’s features and viewer’s expectations)

geon theory

believes that we have a set of fundamental shapes when perceiving objects

template theory

when you compare an object to all our templates in memory, you need an exact match

prototype theory

when you compare an object to your ideal 'prototype’ or overall average/internal ‘best’

perceptual constancy

the ability to perceive an object as unchanging even though the visual image produced by the object is constantly changing

what are the 5 constancies?

shape, location, size, brightness, and colour

shape constancy

when an object is perceived to have a constant shape despite the shape of its retinal image changing with shifts in pov or position

location constancy

an object is perceived to be stationary despite it changing location on our retina due to body movement

size constancy

an object is perceived to be the same size despite the size of its retinal image varying with distance

brightness constancy

an object is perceived to be the same brightness despite reflecting more or less light onto our retina, scale of white to black

colour constancy

an object is perceived to have a constant colour despite different illumination conditions (white dog looks white under a red light)

what causes constancy?

visual cues

ganglion cells + object recognition

they are the first step to recognizing objects

simple cells

feature detectors that respond maximally to a bar of a certain orientation in a particular region of the retina (location!!!!)

what happens when a simple cell is fired at baseline?

there is no stimulus

what happens when a simple cell is fired at maximally?

there is a bar of light oriented in the “on” region in the receptive field

what happens when a simple cell is fired at below baseline?

there is a bar of light in the “off” region

complex cells

feature detectors that respond maximally to a bar of certain orientation!!!!

what happens when a complex cell is fired at baseline?

there is no stimulus

what happens when a complex cell is fired at maximally?

there is a moving stimulus at the preferred angle (45)

what happens when a complex cell is fired at below baseline?

there is a stimulus moving at other angles (not 45)

hypercomplex cells

feature detectors that respond maximally to a bar of a particular orientation and direction of movement

what happens when a hypercomplex cell is fired at baseline?

there is no stimulus

what happens when a hypercomplex cell is fired at maximally?

there is a stimulus that moves up horizontally in the “on” region

what happens when a hypercomplex cell is fired at below baseline?

there is a stimulus that is in the “off” region moving in the wrong angle/direction

where does the dorsal stream take info to?

the parietal cortex

where does the ventral stream take info to?

the temporal cortex

what do infants prefer to look at?

the most complex stimuli

when do infants begin focusing on whole objects?

after 2 months of age

what parts of the face do infants under 2 months focus on?

the outer contours of the face (chin)

what parts of the face do infants over 2 months focus on?

the inner contours of the face (eyes, mouth)

cataracts

a cloudy lens behind the pupil and iris that disrupt light from passing through the lens

visual agnosia

seeing objects but having difficulty understanding what they are

what happens if you damage your extra striate cortex?

you have disrupted object recognition = visual agnosia

object agnosia

the inability to perceive objects, you can’t name them after seeing them but can when touching them

prosopagnosia

the inability to recognize faces, you can know and describe the face but can’t put it together