Chapter6 Flashcards
Sensitivity
The ability to detect the presence of dimly lit objects.
Acuity
The ability to see the details of objects.
Ciliary muscles
The eye muscles that control the shape of the lens.
Accommodation
The process of adjusting the configuration of the lenses to bring images into focus on the retina.
Binocular disparity
The difference in the position of the same image on the two retinas.
Light
Waves of electromagnetic energy between 380-760 nanometers.
Receptors
Cells that are specialized to receive chemical, mechanical, or radiant signals demo the environment.
Horizontal cells
Type of retinal neurons whose specialized function is lateral communication.
Bipolar cells
Bipolar neurons that form the middle layer of the retina.
Amacrine cells
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.
Blind spot
A gap in the receptor layer due to the optic nerve leaving the eyeball.
Fovea
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.
Completion
Filling in the blind spot with information provided by the receptors around the blind spot.
Surface interpolation
The process by which the visual system perceives large surfaces, by extracting information about edges and from it, inferring the appearance of adjacent surfaces.
Cones
The visual receptors of the retina that mediate high acuity color vision in good lighting.
Rods
The visual receptors of the retina that mediate achromatic, low acuity vision under dim light.
Duplexity theory
The theory that cones and rods mediate different kinds of vision.
Photopic vision
Cone-mediated vision. Predominates in good lighting and provides high-acuity color perceptions of the world.
Scotopic vision
Rod-mediated vision. Predominates in dim illumination, there is not enough light to reliably excite cones.
Nasal hemiretina
The half of each retina next to the nose.
Temporal hemiretina
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.
Purkinje effect
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)
Saccades
Small jerky movements or flicks.
Transduction
The conversion of one form of energy to another
Rhodopsin
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.
Absorption spectrum
A graph of the ability of a substance to absorb light of different wavelengths.