PSYCH 100: Sensation and Perception

Sensation

detecting physical energy with our sense (eyes, ears, skin, nose, tongue

Perception

the brain’s interpretation of raw sensory information

Illusion

the way we perceive a stimulus doesn’t match its physical reality

Transduction

conversion of an external stimulus into a neural signal

Sensory receptors

specialized cells designed to convert a certain kind of external information into a neural signal (mind only contact with outside world)

Sensory adaptation

sensory neurons adjust their sensitivity based on recent stimulus history

Aftereffects

opposing sensory or perceptual distortions that occur after adaption

Waves

sound and light are _

Psychophysics

the study of how our sensations (psychological events) correspond to physical events in the world

Absolute threshold

the lowest level of stimulus needed for the nervous system to detect a change 50% of the time

Just Noticeable Differences (JND)

the smallest change in the intensity of a stimulus that we can detect

Weber’s Law

the stronger the stimulus the bigger the change needed to detect it

Signal Detection Theory

how stimuli are detected under different conditions

what you are trying to detect

signal

noise

similar stimuli that might complete with the signal and interfere with your ability to detect the signal

Signal-to-noise ratio

difficulty of detecting the signal depends on the strength of the signal in relation to the strength of the noise

Dichotic listening

cocktail party effect

important information pops out in a conversation that you are not attending

inattentional blindness

occurs when unattended stimuli are ignores as if they weren’t there

Change blindness

version of this that occurs when you fail to detect obvious change in your environment

Attention

allows us to focus on sensory information and deemphasize other information making it easier to detect what we’re interested in

Bottom-Up processing

constructing a representation from parts and basic features (sensation) 

Top-Down processing

processing influenced by previous experience and knowledge

Perceptual sets

set formed when our expectation influence our perceptions

Sclera

white part of eye

Pupil

Circular hole where light enters

Iris

colored portion of the eye that controls pupil size (letting in more or less light)

Cornea

curved, transparent layer covering the iris and pupil that helps focus light

Lens

oval shaped disc that bends light

Accommodation

changing the lens’ shape to focus on the near/far objects

Myopia

(nearsightedness) if your eye is too long

Hyperopia

(farsightedness) eye is too short

Retina

Membrane at the back of the eye responsible for converting light into a neural signal

Fovea

central portion of the retina, responsible for visual acuity (very small)

acuity

sharpness of vision

saccades

small jerky movements of the eye allowing for rapid changes of focus

rods

(photoreceptor) respond under low level light, not color sensitive, more common outside of fovea

Cones

(photoreceptor) sensitive to fine detail, primarily located in fovea, color sensitive, less plentiful than rods

optic nerve

bundle of axons that travels from the retina to the brain

blind spot

area of the retina where the optic nerve exits the eye

object processing

ventral “what” stream, color, texture, shape, size

spatial processing 

dorsal “where” stream, location, movement, spatial relations

White objects

reflect all light

Black objects

reflect no light

Hue

color of light, corresponds to wavelength

Trichromatic Theory

color vision is based on three primary colors: red, green, blue

Opponent process theory

we perceive colors in terms of three pairs of opponent color (red-green, blue-yellow, black-white)

Color blindness

inability to see some or all colors due to loss of one or more types of cones

Depth perception

ability to judge distance and spatial relations depending on binocular and monocular depth cues

Binocular depth cues

involves two eyes

Monocular depth cues

involve one eye

Binocular disparity

each eye sees slightly different images, brain can judge depth

Convergence

eyes converge to see near objects

Relative size

distance objects look smaller than objects look closer (mono)

texture gradient

texture is more clear on closer objects (mono)

interposition

closer objects appear in front of distant objects

linear perspective

parallel lines converge with distance

height in plane

distant objects appear higher than closer objects

Light and shaow

shadow can tell us about form

motion parallax

closer objects pass more quickly than distant obejcts

perceptual constancy

we perceive objects as constant despite change in sensations that arise from those objects

shape constancy

perceived shape is constant even thought shape of the image varies

size constancy

perceive stimuli as consistent across varied conditions

color constancy

perceive stimuli as consistent across varied conditions