L.3 Sensation and Perception

sensation

detecting environmental stimuli (eg. light) / stimuli from body (eg. pain)

perception

interpreting sensory information based on knowledge

sensory receptors

specialized cells that detect change in internal or external conditions

sensory transduction

stimulus —> sense organs —> neural activity —> brain

absolute threshhold

the smallest amount of stimuli that can be detected

how light enters the eye:

cornea —> pupil —> lens → retina

lens accomodation

changing the shape of lens to allow for extra power and focus

flat lens

distant objects – little refraction

fat lens

near objects – greater refraction

photoreceptors

sensory receptors sensitive to light: rods, cones, ganglion cells

rods

peripheral vision

permits vision in low light

detects black, white, and gray

cones

foveal vision

permits vision in bright light

fine detail and color – blue, green, red

dichromats

deficits in color vision (ishihara color test)

depth perception

ability to use 2D image on retina to perceive 3D images