CHAPTER 03 | PART 1 Flashcards
nerves of the eyes sends a pattern of impulses similar to the perceived object
RENE DESCARTES
which neurons are active
- amount of response
CODING
law of specific nerve energies
> “brain codes information based on the activated neurons, and how active they are at any moment”
JOHANNES MULLER
- hole where light passes through
- contracts depending on the amount of light
PUPIL
clear, dome-shaped surface that covers the front of the eyes
- light enters
CORNEA
focuses the light to the retina
LENS
- colored part of the eyes
- regulates the amount of light that reaches the retina
IRIS
- contains photoreceptors responsible for the creation
of electrical impulses - inside-out
- signals pass through layers before being received by
the receptors then goes back to the optic nerve
RETINA
- distorts light for fine details
- acute, detailed vision
- midget ganglion cells
- better acuity than
peripheral vision
FOVEA
- gaps where optic nerves exit
- difference between left and
right eye
BLIND SPOT
- weak lights
- rhodopsin: responds to light;
scotopic vision
RODS
- bright lights
- color vision
CONES
- release energy
when struck by light - vitamin A + opsin
- light absorption
PHOTOPIGMENTS
depending on the responses across receptors and their sensitivity to wavelength
COLOR VISION: TRICHROMATIC THEORY
by Thomas Young
response of three types of cones
- amount of light affects intensity
COLOR VISION: TRICHROMATIC THEORY
by Henry Von Helmholtz
COLOR VISION: OPPONENT PROCESS THEORY by Edward Hering
- opposites
- continuum: red vs. green, blue vs. yellow, black vs. white
- negative afterimage
- excitations and inhibitions in ganglion cells
- cortex compares information from retina to determine brightness and color
- color constancy: recognizing colors despite changes in lighting
- visual perception requires reasoning
COLOR VISION: RETINEX THEORY by Edwin Land
inhibition of neurons due to the excitation of a neighboring neuron
- sharpening contrasts to emphasize the borders of objects
LATERAL INHIBITION
- area in visual space that excites or inhibits a receptor
- sensitive tiny receptive fields in rods and cones
- rods and cones => bipolar cells => ganglion cells
RECEPTIVE FIELD
DEPRIVED EXPERIENCE IN ONE EYE…
weakens neural responses
DEPRIVED EXPERIENCE IN BOTH EYES
- weakens neural responses, with the visual cortex responding to other stimuli (touch and hearing)
- sensitive periods
blurring of vision for lines in one direction caused
Astigmatism
UNCORRECTED STIMULATION IN THE
EYES…
- stereoscopic depth perception
> comparison of input from both eyes
> retinal disparity
> cloudy spots in the lens
corrected through surgery
cataracts
guidance of movement, visual spatial perception, visually guided behavior
DORSAL STREAM
- perception of objects
- Temporal Cortex
- visual pattern recognition
- conscious visual percetion
VENTRAL STREAM
- identifiable objects
- viewer’s perception
- similar response to stimulus regardless of change in
various aspects
INFERIOR TEMPORAL CORTEX
inability to recognize objects despite satisfactory vision
> visual lack of knowledge
> pointing to or describing objects without knowing them
Visual Agnosia
> inability to recognize faces
connections to and from the fusiform gyrus
Prosopagnosia
pictures of places
parahippocampal cortex
faces
fusiform gyrus
MIDDLE TEMPORAL CORTEX (MT; V5)
- overall patterns
- color-insensitive
- speed and direction of moving objects
- acceleration, deceleration, and absolute speed
> impairment in the ability to perceive movemen
Motion Blindness
