4.2 Seeing Flashcards
(32 cards)
electromagnetic energy
pulses of energy waves that can carry information from place to place
wavelength
the distance between one wave peak and the next wave peak
visible spectrum
our eyes detect only the range from about 400 to 700 billionths of a meter
cornea
a clear covering that protects the eye and begins to focus the incoming light
pupil
a small opening in the center of the eye
iris
the colored part of the eye that controls the size of the pupil by constricting or dilating in response to light intensity
lens
a structure that focuses the incoming light on the retina
retina
the layer of tissue at the back of the eye that contains photoreceptor cells
visual accomodation
the process of changing the curvature of the lens to keep the light entering the eye focused on the retina
nearsighted
if focus is in front of retina
farsighted
the focus is behind the retina
optic nerve
a collection of millions of ganglion neurons that sends vast amounts of visual information, via the thalamus, to the brain
Rods
visual neurons that specialize in detecting black, white, and gray colors
Cones
visual neurons that are specialized in detecting fine detail and colors
fovea
which is the central point of the retina
blindspot
there are no photoreceptor cells at the place where the optic nerve leaves the retina
feature detector neurons
specialized neurons, located in the visual cortex, that respond to the strength, angles, shapes, edges, and movements of a visual stimulus
hue
- the shade of a color
- conveyed by the wavelength of the light that enters the eye (we see shorter wavelengths as more blue and longer wavelengths as more red)
intensity
height of the wave (bigger or more intense waves are perceived as brighter)
Hermann von Helmholtz (1821–1894)
he theorized that color is perceived because the cones in the retina come in three types
Young-Helmholtz trichromatic color theory
what color we see depends on the mix of the signals from the three types of cones
color blindness
the inability to detect either green and/or red colors
opponent-process color theory
proposes that we analyze sensory information not in terms of three colors but rather in three sets of “ opponent colors‖: red-green, yellow-blue, and whiteblack
gestalt
a meaningfully organized whole