The Brain and Behavior: Chapter 5 Vision

pupil

opening in the center of the iris where light enters

retina

rear surface of the eye, which is lined with visual receptors

pupil

opening in the center of the iris where light enters

retina

rear surface of the eye, which is lined with visual receptors

optic nerve

group of ganglion cell axons that exit through the back of the eye

blind spot

area at the back of the retina devoid of receptors

fovea

tiny area of the retina specialized for acute, detailed vision

law of specific nerve energies

rule that whatever excites a nerve always sends the same information to the brain

bipolar cell

type of neuron in the retina that receives input directly from the receptors

ganglion cell

type of neuron in the retina that receives input from the bipolar cells

midget ganglion cell

neuron in the fovea of humans and other primates

cone

type of retinal receptor that contributes to color perception

photopigment

chemical contained in rods and cones that release energy when struck by light

visual field

area of the world that an individual can see at any time

negative color afterimage

result of staring at a colored object and then looking at a white surface

opponent-process theory

idea that we perceive color in terms of opposites

color constancy

ability to recognize colors despite changes in lighting

horizontal cell

type of cell that receives input from receptors and delivers inhibitory input to bipolar cells

lateral geniculate nucleus

thalamic nucleus that receives incoming visual information

lateral inhibition

reduction of activity in one neuron by activity in neighboring neurons

receptive field

area in visual space that excites or inhibits any neuron

parvocellular neuron

small cell body with small receptive field in or near the fovea

magnocellular neuron

large cell body with a large receptive field that is distributed evenly throughout the retina

primary visual cortex (area V1)

area responsible for the first stage of visual processing

blindsight

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

simple cell

cell that has a receptive field with fixed excitatory and inhibitory zones

complex cell

cell that responds to a pattern of light in a particular orientation

end-stopped cell

cell with a strong inhibitory field at one end of its field

hypercomplex cell

cell that responds to a bar-shaped pattern of light in a particular orientation

strabismus

condition in which the eyes do not point in the same direction

astigmatism

decreased responsiveness caused by an asymmetric curvature of the eyes

ventral stream

visual path in the temporal cortex that is specialized for identifying and recognizing objects

dorsal stream

visual path in the parietal cortex that helps the motor system locate objects

visual agnosia

inability to recognize objects despite otherwise satisfactory vision

fusiform gyrus

brain area of the inferior temporal cortex that recognizes faces

prosopagnosia

inability to recognize faces due to damage of several brain areas

saccade

voluntary eye movement