sensations (eyesight)

unit 2

sensation

a process where our sensory receptors and nervous system receive and represent stimulus energy

absolute threshold

minimum needed stimulation needed to detect a particular stimulus 50% of the time

difference threshold

minimum difference detected between two stimuli 50% of the time

webers law

the larger or stronger a stimulus, the larger change required for a person to notice that anything has happened

sensory adaptation

diminished sensitivity to a constant stimulus

accommodation

the process by which the eye’s lens changes shape to help focus on near or far objects

lens

transparent structure behind the pupil that changes shape to focus images on the retina

retina

the inner surface of the eye that is sensitive to light. also contains receptor rods and cones plus layers of neurons that begin the processing of visual info

blind spot

the location in the retina where there are no receptors there

blindsight

we can see things we dont perceive

acuity

the sharpness of vision

nearsightedness

close objects are seen more clearly than distant objects

farsightedness

faraway objects are seen more clearly than near objects

astigmatism

the shape of the lens is oval instead of round

presbyopia

loss of the lens’ flexibility over time, necessitates reading glasses

rods

detect movement, black, white, and gray. they activate best in twilight or low light

cones

detect fine detail and color vision. also activate best in daylight or well-lit conditions

parallel processing

processes several parts of a stimuli simultaneously

afterimages

overstimulation of photoreceptors leads to continued visual perception even after stimulus is removed

prosopagnosia

face blindness; a neurological disorder impairing the ability to recognize faces. this impacts the ability to identify individuals, so they rely on non-facial cues

dichromatism

colorblindness where one type of cone is missing or dysfunctional. this means that you are not able to distinguish between certain colors like red and green

monochromatism

total color blindness, two or three cones are nonfunctioning, resulting in only seeing shades or grey