perception Flashcards
perception includes:
visual perception
audition
touch
pain
world to visual signal in brain
signal of 400-700mm for brain to process and encode
photoreceptors convert light wave energy into neural signal
- light energy –> neural activity
structure and function of the eye
Retina
- image on the retina is flipeed upside down and backwards
- light wave energy into back surface of eye
- shadows and disruptions are not seen
photoreceptor specialised function
first stage of information processing
2 photoreceptor types
Cones
Rods
RODS
work in dim lighting
- sensitive to movement but not fine detail or colour
- in dim lighting no colour, cone photoreceptors can’t work
* found in the periphery
CONES
function and location
work in good lighting and are sensitive to fine detail and colour
* interpret colour detail
* predominately found at the fovea
* at the fovea - 170 thousand receptors per mm^2
Visual acuity
ability to see fine detail
- this is determined by the properies of rods and cones
- no light receptors when blinking
context for vision
C + C
- colour contrast - colours we perceive are influenced by its surrounding
- colour constancy - tendency of a surface to appear the same colour under range of illuminants
* need to discount the illuminant (light) and determine true colour
light sources - bent shape, colours to different, creates shadow
retinal image to recognisable objects
- visual info seen on right of fixation is processed in left of brain
- visual info on left of fixation is processed on right
of brain
primary visual cortex
V1
first stage of cortical (visual processing)
- involved with the coding of lines and edges in visual scene
cortical cell sensitive to orientation
rules for visual cues
4 gestalt principles
linking oriented lines to outline shapes
- organise images into figures of interest and background = figure ground segregation
* similarity
* proximity
* closure
* continuity
Similarity
Proximity
Closure
Continuity
2 cues
depth of vision
- monocular cues
- binocular cues
M
- linear perspective
tendency for lines to converge when parallel
further away = smaller
eg. train tracks