sensation and perception Flashcards
definition of colour
visible light forms narrow band of frequencies in electromagnetic spectrum and within band different frequencies have different hues
hue
determined by wavelength of light reflected
saturation
how much white light is mixed in pure hue
what does wavelength determine
hue
blue sensitive cones
cones respond to short wavelengths 419nm
green sensitive cons
medium wavelengths, 531nm
red sensitive cones
long wavelengths 558nm
pigment in cones
determine which wavelengths they best resond to
how does brain interpret colour
from cones light is encoded as electrical signal
anopias
insensitive to long, medium and short wavlenegths from missing cone
anomolies
misalignment of l or m wavelengths in trichomats due to distribution deficiecny
occulomotor cues
depend on ability to sense position of eyes and tension in eye msucles
what happens when you look at close up images
tightening of ciliary muscles
emmerts law
size constancy- objects that are the same size look differnt in retinal image if theyre at different distances
atmospheric perspective
distant objects less sharp as light from distant object has to pass through more air and more blue light
motion parallax
as observer moves relative to 3D scene, nearby objects appear to move slower
stereo blindness
strabismus, failure to converge on common target
Marr’s approach
bottom up, computational model, retinal image analysed sequentially at different levels
pragnanz figure ground segregation
best solution is most stable and simple
affecting properties of figure ground segregation
symmetry, convexity, area, orientation, meaning/ importance
gestalts approach
whole is greater than sum of its parts
gestalts features
similarity, good continuation, proximity, connectedness, closure, common fate, familiarity, invariance
rods
night, high convergence, low acuity, monochromatic
cones
daytime, less convergence, high acuity, 3 cones of colour
receptive fields
area on retina which elicits change in firing rate of cell when stimulated
retinal ganglion cells
condense raw data/ info from photo receptors
lateral inhibition
a neuron’s response to stimulus is inhibited by excitation of neighbouring neurons
sensory receptor cell
specialised neuron which responds to a particular physical property of environmental stimuli
