Chapter 4: Senstation and Perception Flashcards
Binocular Depth Cues
distance cues that are based off on the differing perspectives of both eyes
Cones
photoreceptors that are sensitive to the different wavelengths of the light that we perceive as colour
Convergence
occurs when the eye muscles contract so that both eyes focus on a single object
Cornea
The clear layer that covers the front portion of the eye and also contributes to the eye’s ability to focus
Dark adaption
the process by which the rods and cones become increasingly sensitive to the light under the low levels of illumination
A dorsal stream
a neural circuit for vision that extends from the visual cortex to the parietal lobe
Feature detection cells
set of cells in the visual cortex that respond selectively to simple and specific aspects of a stimulus such as angles and edges
Fovea
the central region of the retina
Iris
A round muscle that adjusts the size of the pupil; it also gives the eyes characteristic colour
Lens
a clear structure that forces light onto the back of the eye
Monocular cues
depth cues that we can perceive with only one eye
Opponent process theory
theory of colour perception stating that we perceive colour in terms of opposing pairs: red to green, yellow to blue, and white to black
Optic chiasm
the point at which the optic nerve crosses at the mid line of the brain
optic nerve
a dense bundle of fibers that connect to the brain
perceptual constancy
the ability to perceive objects as having constant shape, size, and colour despite changes in perception
prosopagnosia
an inability to recognize faces or face blindness
pupil
regulates the amount of light that enters the eye by changing size, it dilates (expands) to allow more light in and constricts (shrinks) to allow less light in
retina
lines the inner surface of the eye and consists of specialized receptors that absorb light and send signals related to the properties of the light to the brain
retinal disparity (binocular disparity)
the difference in the relative position of an object as seen by both eyes, which provides info to the brain about depth
rods
photoreceptors that occupy peripheral regions of the retina; they are highly sensitive under low light levels
Scerla
is the white outer surface of the eye
trichromatic theory (young Helmholtz theory)
maintains that coulour vision is determined by three different cone types that are sensitive to short, medium and long wavelengths of light
ventral stream
a neural circuit for vision that extends from the visual cortex to the lower part of the temporal lobe
How does visual info travel from the eye through the brain to give us the experience of sight
Light is transformed into the neutral signal by photoreceptors in the retina
- this info is relayed to the optic nerve through the thalamus and then to the occipital lobe of the cortex
- from this location, neural circuits travel to the other regions for specific levels of processing
- these include the temporal lobe for object recognition (ventral stream) and the parietal lobe for the visually guided movement (dorsal stream)
Explain the TT colour theory
- TT: the retina contains 3 cones that are sensitive to diff wavelengths.
- Colour is experienced as the net combined stimulation of these receptors.
- not supported by phenomena such as the negative afterimage
explain the OP colour theory
-emphasizes how colour perception is based on excitation and inhibition of opposing colours (red-green, blue-yellow, white to black.
explain how we perceive depth in our visual field?
- pictorial depth cues: linear perspective texture gradient height in plane relative size
How do we perceive objects and faces
- accomplished by specialized perceptual regions of the temporal lobe (ventral stream of vision)
- damage to this could cause impairments in recognizing specific categories of objects
- ## facial recognition is a specialized perceptual process, which is supported by evidence from people who are face blind but are otherwise successful at seeing objects
absolute threshold
the minimum amount of energy or quantity of a stimulus required for it to be reliably detected at least 50% of the time
bottom-up process
occurs when we perceive individual bits of sensory information and use them to construct a more complex perception