Biological Psychology Chapter 5: Vision

simple cell

a receptive field with fixed excitatory and inhibitory zone, the less the cell responds

negative color afterimage

a replacement of red you had been staring at with green, yellow and blue, black and white

motion blindness

ability to see objects but impairment at seeing whether they are moving or which direction and how fast

in the fovea, each ___ has its own line to the brain in midget ganglion cells

cone

selective attention

focusing conscious awareness on a particular stimulus

feature detectors

neurons whose responses indicate the presence of a particular feature

fixations

pauses during which eyes are almost stationary and visual information is taken in

binocular

stimulation from both eyes

optic chiasm

the optic nerves from the two eyes meet; half of the axons from each eye cross to the opposite side of the brain

visual field

the part of the world you see

blind spot

the point where light leaves the eye where there are no receptors

sensation

the process of detecting stimuli in the environment, or within the body

retina

the rear surface of the eye

lateral inhibition

the reduction of activity in one neuron by activity in neighboring neurons; heightens contrast

transduction

the translation of information from the environment into neural signals

dorsal stream

through the parietal cortex, "where" or "how" pathway; visually guided movements

top-down processing

to screen out information irrelevant to the current task

stimulus (light) goes through ______ to fire action potentials to the brain

transduction

parvocellular neurons

with small cell bodies and small receptive fields; are mostly in or near the fovea

light converts ___-____-____ to all-trans-retinal, thus releasing energy that activates second messengers within the cell

11-cis-retinal

humans perceive wavelengths between _____ and ______

400nm; 750nm

astigmatism

a blurring of vision for lines in one direction caused by an asymmetric curvature of the eyes

fovea

a tiny area specialized for acute, detailed vision; blood vessels and ganglion cell axons are almost absent near the fovea

continuous flash suppression

a viewer is conscious of the flashing stimuli and not the steady picture

cones

abundant in and near the fovea; are less active in dim light, more useful in bright light, and essential for color vision

rods

abundant in the periphery of the human retina, respond to faint light but are not useful in daylight because bright light bleaches them

primary visual cortex

also known as area V1 and striate cortex; information from the lateral geniculate nucleus of the thalamus goes to this area in the occipital lobe

receptive field

an area in visual space that excites or inhibits it

pupil

an opening in the center of the iris where light enters

the responses of cells in V4 correspond to the ____ or _____ color of an object

apparent; perceived

some can identify an object's color, direction of movement, and approximate shape using ______ ______

area V1

the activity in ____ ____ corresponds to what you think you see, not what the object really is

area V1

MT (middle temporal cortex); MST (medial superior temporal cortex)

area V5 (MT); both for motion perception; receive input mostly from magnocellular path, which detects overall patterns, including movement over large areas of the visual field; color insensitive

light ----> retina ----> _____ & _____ cells ----> _____ & _____ cells

bipolar and horizontal; amacrine and ganglion

damage to the connections between primary visual cortex and temporal cortex

cause impairment of identifying shapes orientation of an object

photopigments

chemicals that release energy when struck by light

wavelength is to _____; amplitude is to ______

color; brightness

color vision deficiency

colorblindness; results when people with certain gees fail to develop one type of cone; develop an abnormal type of cone

the retinex theory

cortex compares information from various parts of the retina to determine the brightness and color for each area

if eyes remain shut longer, ______ responses start to become sluggish and lose their well-defined receptive fields. eventually, ____ cortex starts responding to _____ and ____ stimuli instead

cortical; visual; auditory; touch

sensitive period

experiences have a particularly strong and enduring influence

optic nerve

formed when ganglion cell axons join; light exits through the back of the eye

amacrine cells

get information from bipolar cells to other bipolar, amacrine, and ganglion cells

end-stopped or hypercomplex cells

has a strong inhibitory area at one end of its bar-shaped receptive field

prosopagnosia

impaired ability to recognize faces; stemmed from either brain damage or developed few connections

ganglion cells

information gets sent to this part after bipolar cells to the brain

magnocellular neurons

larger cell bodies and receptive fields; distributed evenly throughout the retina

strabismus (strabismic amblyopia)

lazy eye; a condition in which the eyes do not point in the same direction

bipolar cells

located closer to the center of the eye; messages are received here first

complex cells

located in areas V1 and V2, do not respond to the exact location of the stimulus; responds to a pattern of light in a particular orientation anywhere within its large receptive field

horizontal cells

make inhibitory contact onto bipolar cells, which in turn make synapses onto amacrine cells and ganglion cells

lateral geniculate nucleus

part of the thalamus; ganglion cell axons go to this area then sends axons to other parts of the thalamus and the visual cortex

primate ganglion cells fall into three categories:

parvocellular, magnocellular, and koniocellular

opponent-process theory

perceive color in terms of opposites

The Trichromatic (Young-Helmholtz) Theory

perceive color through the relative rates of response by three kinds of cones, each one maximally sensitive to a different set of wavelengths

towards the ____ of the retina, more and more receptors converge onto bipolar and ganglion cells

periphery

secondary visual cortex (area V2)

processes information further and transmits it to additional areas from primary visual cortex (area V1)

opsins

proteins that modify the photopigments' sensitivity to different wavelengths of light

the _____ _____ of a rod or cone is simply the point in space from which light strikes the cell

receptive field

the ______ send messages to excite the closest ______ ______ and also send messages to slightly inhibit them and the neighbors to their sides

receptors; bipolar cells

inferior temporal cortex

respond to meaningful objects

fusiform gyrus

responds more strongly to faces than anything else

stereoscopic depth perception requires the brain to detect ____ ____

retinal disparity

vision is poorer at night because you use _______

rods

the vertebrate retina contains two types of receptors:

rods and cones

____ outnumber ____ by about 20 to 1 but _____ provide 90% of brain's input

rods; cones; cones

damage to the dorsal stream

see objects but don't integrate their vision well with their arm and leg movements; able to read and recognize objects but cannot reach or grasp the object

blue/purple have _____ wavelengths, while red/yellow have _____ wavelengths

short; long

koniocellular neurons

small cell bodies; they occur throughout the retina

ventral stream

specialized for identifying and recognizing objects; "what" pathway

waterfall illusion

suggests that you have fatigued the neurons that detect downward motion, leaving unopposed the detectors for the opposite motion

color constancy

the ability to recognize colors despite changes in lighting

blindsight

the ability to respond in limited ways to visual information without perceiving it consciously

bottom-up processing

the brain organizes simple sensory input into meaningful perception

saccades

the decrease in activity of area MT and parts of the parietal cortex during voluntary eye movements

retinal disparity

the discrepancy between what the left and right eyes see

inattention blindness

the failure to see an object that is looked directly, even highly visible

midget ganglion cells

the ganglion cells in the fovea of humans and other primates

perception

the interpretation of sensory information received by the brain

visual agnosia

visual lack of knowledge; damage in temporal cortex; able to point to visual objects and slowly describe them but fail to recognize what they are

law of specific nerve energies

whatever excites a particular nerve establishes a special kind of energy unique to that nerve; impulses in certain neurons indicate light, others indicate sound, touch, or other sensations