Sensation and Perception Flashcards
stimulus
- elicits reaction from sensory systems
transduction
translation from stimulus to neural signal
sensory adaptation
pay less attention to a non changing source of stimulation
selective attention
prioritize input to focus on avail info and exclude the rest
bottom-up processing
building simple input into more complex perceptions
eg. learning a new word
top-down processing
stuff u know already help u interpret incoming sensory info
eg. recognizing a friend
psychophysics
Gustav Fechner
- relationship between physical qualities of stimuli and response they produce
absolute threshold
smallest amount of stimulus that can be detected
eg. seeing light from a candle flame 30 miles away at night
difference shreshold
smallest detectable difference between 2 stimuli
eg. difference between 2 weights
signal detection
detection of faint, uncertain stimuli
1. intensity of stimulus
2. criteria for deciding whether stimulus occurred
vision
- process reflected light
- approx 50% of cerebral cortex processes visual info
visual stimulus
visible light or energy within electromagnetic spectrum that our visual system responds to
cornea
clear surface at front of eye that begins to bend light into eye
pupil
opening formed by iris
iris
adjusts opening of pupil in response to amount of light and in response to signals from the autonomic nervous system
lens
bends light toward retina
retina
layers of visual processing cells in back of eye - converts light into electrical signals
fovea
- part of retina for highly detailed vision
- central vision
- image of object we stare directly at is projected onto fovea
rod
photoreceptor detecting dim light
- more in PHERIPHERY of retina
- provide no colour, clear or sharp images
- around 90 million rods
cone
photoreceptor processing colour and detail
- functions best under sharp, bright light
- 4-5 million cones
blind spot
optic nerve exit w/o rods or cones
optic nerve
nerve exiting retina of eye
partial crossing
- axons closest to nose cross over to other hemisphere while axons on outside go to same hemisphere
- everything to the left of centre in visual field is processed by the right hemisphere and vice versa
trichromatic theory
based on existence of different types of cones for detection of short (blue), medium (green) and long (red) wavelengths
opponent process theory
we have red-green and blue-yellow color channels
- if u stare at one colorand then look at a white wall you’ll start to see the other
colorblind
- people who have two types of cones instead of the usual three
organization principle
identify main object in the scene
proximity principle
objects that are close together tend to be grouped together
continuity principle
we assume that points which form smooth lines when connected belong together
closure principle
we “fill in the blanks” when we see an image made of lines or gaps
simplicity principle
we will use the simplest solution to a perceptual problem
depth perception
ability to use 2D image projected onto retina to perceive 3D
monocular cue
depth cue using only ONE eye
- texture gradients and shading
- occlusion: blocking distant object by closer objects
binocular cue
- use both eyes
- retinal disparity: difference between images projected onto each eye
- provides info of relative distance between two objects
