Test 2 (Chapter 6) Flashcards
nanometers
billionths of a meter; light is between 380 and 760
infrared waves
wavelengths that are too long for humans to see but rattlesnakes can see them
wavelength
a property of light that plays in important role in the perception of color
intensity
a property of light that plays an important role in the perception of brightness
brightness
intensity of light
sensitivity
in vision, the ability to detect the presence of dimly lit objects
acuity
the ability to see the details of objects
retina
the amount of light that reaches this part of the eye is regulated by the irises
pupil
light enters the eye through this part of the eye which is a hole in the lens
iris
the donut-shaped bands of contractile tissue that gives our eyes their characteristic color
ciliary muscles
the eye muscles that control the shape of the lenses
accomodation
the process of adjusting the configuration of the lenses to bring images into focus on the retina
converge
turn slightly inward
binocular disparity
the difference in the position of the retinal image of the same object on the two retinas
receptors
cells that are specialized to receive chemical, mechanical, or radiant signals from the environment; also proteins that contain binding sites for particular neurotransmitters
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 neurons whose specialized function is lateral communication
blind spot
the area on the retina where the bundle of axons on the retinal ganglion cells penetrate the receptor layer and leave the eye as the optic nerve
fovea
the central indentation of the retina, which is specialized for high-acuity vision
completion
the visual system’s automatic use of information obtained from receptors around the blind spot, or scotoma, to create a perception of the missing portion of the retinal image
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 usual receptors in the retina that mediate high acuity color vision in good lighting
rods
the visual receptors in the retina that mediate achromatic, low-acuity vision under dim light
duplexity theory
the theory that cones and rods mediate photopic and scotopic vision, respectively
photopic vision
cone-mediated vision, which predominates when lighting is good
scotopic vision
rod-mediated vision, which predominates in dim light
nasal hemiretina
the half of each retina next to the nose
temporal hemiretina
the half of each retina next to the temple
spectral sensitivity curve
a graph of the relative brightness of light in the same intensity presented at different wavelengths
photopic spectral sensitivity curve
the graph of the sensitivity of cone-mediated vision to different wavelengths of light
scotopic spectral sensitivity curve
the graph of the 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 intesity, in dim light, blue and green wavelengths look brighter than red and yellow wavelengths of equal intensity
fixational eye movements
involuntary movements of the eyes (tremor, drifts, and saccades) that occur when a person tries to fix his or her gaze on (i.e., stare at) a point
saccades
the rapid movements of the eyes between fixations