Flashcards in Chapter6 Deck (77):
The ability to detect the presence of dimly lit objects.
The ability to see the details of objects.
The eye muscles that control the shape of the lens.
The process of adjusting the configuration of the lenses to bring images into focus on the retina.
The difference in the position of the same image on the two retinas.
Waves of electromagnetic energy between 380-760 nanometers.
Cells that are specialized to receive chemical, mechanical, or radiant signals demo the environment.
Type of retinal neurons whose specialized function is lateral communication.
Bipolar neurons that form the middle layer of the retina.
A type of retinal neuron whose specialized function is lateral communication.
Retinal ganglion cells
Retinal neurons whose axons leave the eyeball and form the optic nerve.
A gap in the receptor layer due to the optic nerve leaving the eyeball.
An indentation at the center of the retina that is specialized for high-acuity vision. The thinning of the retinal ganglion layer reduces distortion of incoming light.
Filling in the blind spot with information provided by the receptors around the blind spot.
The process by which the visual system perceives large surfaces, by extracting information about edges and from it, inferring the appearance of adjacent surfaces.
The visual receptors of the retina that mediate high acuity color vision in good lighting.
The visual receptors of the retina that mediate achromatic, low acuity vision under dim light.
The theory that cones and rods mediate different kinds of vision.
Cone-mediated vision. Predominates in good lighting and provides high-acuity color perceptions of the world.
Rod-mediated vision. Predominates in dim illumination, there is not enough light to reliably excite cones.
The half of each retina next to the nose.
The half of each retina next to the temples.
Photopic spectral sensitivity curve
The graph of sensitivity of cone-mediated vision to different wavelengths of light.
Scotopic spectral sensitivity curve
The graph of sensitivity of rod-mediated vision to different wavelengths of light.
In intense light, red and yellow wavelengths look brighter than blue or green wavelengths of equal intensity; in dim light, blue and green wavelengths look brighter than red and yellow wavelengths of equal intensity.
Fixation eye movements
Involuntary movements of the eyes that occur when a person tries to fix their gaze on a point (tremor, drifts, saccades)
Small jerky movements or flicks.
The conversion of one form of energy to another
The photopigment of rods. When exposed to intense light, it is bleached and looses its ability to absorb light. When returned to the dark, it regained its redness and ability to absorb light.
A graph of the ability of a substance to absorb light of different wavelengths.
The entire area that you can see as a particular movement.
Conversion of light to neural signals by the visual receptors.
A substance that absorbs light.
Retina-geniculate striate pathways
Conducts signals from each retina to the primary visual cortex/striate cortex via the lateral geniculate nuclei.
Primary visual cortex/ striate cortex
The area of the cortex that receives direct input from the lateral geniculate nuclei.
Lateral geniculate nuclei
The six-layered thalamic structures that receive input from the retinas and transmit their output to the primary visual cortex/ striate cortex.
Organized, like the primary visual cortex, according to a map of the retina. There is a disproportionate representation of the fovea.
Parvocellular layers (P layer)
Particularly responsive to color, fine pattern details, and stationary or slow moving objects. Cones provide most of the input. Top four layers.
Magnocellular layers (M layer)
Particularly responsive to movement. Rods provide most of the input. Bottom two layers.
intensification of the perception of edges
very large receptors interconnected by a lateral neural network
receptors fires, it inhibits its neighbors via the lateral neural network
the area of the visual field within which it is possible for a visual stimulus to influence the firing of that neuron
uncolored light shone on the retina
each neuron had a receptive field in one eye but not the other
respond to lights shone in the central region of their receptive fields "on" firing and to lights shone in the periphery of their receptive fields with inhibition, followed by "off" firing when the light is turned off
respond with inhibition and "off" firing in response to lights in the center of their receptive fields and with"on" firing to lights in the periphery of their receptive fields
Neurons in the visual cortex that respond maximally to straight-edge stimuli in a certain position and orientation
Neurons in the visual cortex that respond optimally to straight-edge stimuli in a certain orientation in any part of their receptive field
respond to stimulation of either eye
Component theory (trichromatic theory)
theory that the relative amount of activity produced in three different classes of cones by light determines its perceived color
opponent process theory
theory that a visual receptor or a neuron signals one color when it responds in one way (e.g., by increasing its firing rate) and signals the complementary color when it responds in the opposite way (decreasing firing rate)
refers to the fact that the perceived color of an object is not a simple function of the wavelengths reflected by it
the color of an object is determined by its reflectance- proportions of light of different wavelengths that a surface reflects
Dual-opponent color cells
Neurons that respond to the differences in the wavelengths of light stimulating adjacent areas of their receptive field
an enzyme present in particularly high concentrations in the mitochondria of dual-opponent color cells of the visual cortex
peglike, cytochrome oxidase-rich, dual-opponent color columns
secondary visual cortex
those that receive most of their input from the primary visual cortex
visual association cortex
areas that receive input from areas of secondary visual cortex as well as from the secondary areas of other sensory systems
band of tissue in the occipital lobe that surrounds the primary visual cortex
cortex of the inferior temporal lobes
posterior parietal cortex
areas of association cortex that receive visual input are located in several parts in several parts of the cerebral cortex--largest one
area of blindness in the the corresponding area of the contralateral visual field of both eyes
The procedure used to map scotomas
have a scotoma covering half of their visual field
person sees something, he or she will be consciously aware of seeing it
the ability of such patients to respond to visual stimuli in their scotomas even though they have no conscious awareness of the stimuli
flows from the primary visual cortex to the dorsal prestriate cortex to the posterior parietal cortex
flows from the primary visual cortex to the ventral prestriate cortex to the inferotemporal cortex
"where" versus "what" theory
vision is that damage to some areas of cortex may abolish certain aspects of vision while leaving others unaffected
"control of behavior" versus "conscious perception" theory
Theory that the dorsal stream mediates behavioral interactions with objects and the ventral stream mediates conscious perception of objects
visual agnosia for faces
failure of recognition
Fusiform face area
an area of human cortex, located at the boundary between the occipital and temporal lobes, that is selectively activated by human faces
deficiency in the ability to see movement progress in a normal smooth fashion