Unit 3: Sensation and Perception

absolute threshold

the minimum amount of energy or chemicals that can be detected 50% of the time by our senses.

Difference Threshold/just noticeable difference (JND)

The smallest change in stimulation that can be detected 50% of the time (ex. shower temperature difference)

Weber's Law

States that the difference threshold is a constant proportion of the specific stimulus

signal detection theory

a theory predicting how and when we detect the presence of a faint stimulus (signal) amid background stimulation (noise). (hits, misses, false alarms, correct rejections)

signal detection theory - hit

when a signal is present and you noticed the signal

signal detection theory - misses

when a signal is present but you don't notice the signal

signal detection theory - false alarm

when a signal is not present but you notice the signal

signal detection theory - correct rejection

when a signal is not there and you don't notice the signal

subliminal perception

the notion that we may respond to stimuli that are below are level of awareness (only happens in controlled laboratory studies)

Psychophysics

the branch of psychology that deals with the relationship between physical stimuli and mental phenomena (transduction)

Transduction

turning energy into a neural impulse

selective attention

the focusing of conscious awareness on a particular stimulus

cocktail party effect

can listen to one person in the crowd but attention turns away when you hear your name being called

divided attention

concentrating on more than one activity at the same time

inattentional blindness

failing to see visible objects when our attention is directed elsewhere (ex. gorilla test)

change blindness

failing to notice changes in the environment (form of inattentional blindness)

Sensation

The experience of sensory stimulation

Perception

The process of creating meaningful patterns from raw sensory information

bottom-up processing

starts at your sensory receptors and works up to higher levels of processing (lines, angles, colors) (slower but more accurate)

top-down processing

constructs perception from this sensory input by drawing on your experiences and expectations (faster but less accurate)

sensory adaptation

diminished sensitivity as time continues (ex. don't realize your pen is in your ear after a while)

Habituation

an organism's decreasing response to a stimulus with repeated exposure to it (ex. what your house smell's like)

context

The circumstances, atmosphere, attitudes, and events surrounding a text.

perceptual set

a mental predisposition to perceive one thing and not another (ex. seeing ABC or 12, 13, 14 when looking at an image)

schemas

Concepts or mental frameworks that you already know and organize to interpret/categorize information. (ex. school schema)

accommodation

change schema to fit new information

Rods

black and white vision, provide night vision, very sensitive to light, respond to light and dark, many rods connect to single bipolar cell (120 million)

cones

respond to color as well as light and dark, works best in bright light, found mainly in the fovea, only a single cone connects to a bipolar cell

motion detector cells

cells in the visual cortex that are sensitive to an image moving in a particular direction across the retina

feature detector cells

cells in the visual cortex that are sensitive to specific features of the environment

opponent-process theory

the theory that opposing retinal processes (red-green, yellow-blue, white-black) enable color vision. For example, some cells are stimulated by green and inhibited by red; others are stimulated by red and inhibited by green

trichromatic

three different types of cones (red, green, blue/violet), experience of color is the result of mixing of the signals from these receptors

additive color mixing

mixing of lights and different hues (lights, TV, computer monitors)

subtractive color mixing

mixing pigments (ex. paint)

color blindness

dichromatic - when someone cannot see either red/green shades or blue/yellow shades

monochromatic

people can only see in shades of grey

cornea

transparent protective coating over the front of the eye

pupil

small opening in the iris though which light enters the eye

iris

the colored part of the eye

lens

focuses light onto the retina

retina

lining of the eye containing receptor cells that are sensitive to light

fovea

center of visual field

optic nerve

the nerve that carries neural impulses from the eye to the brain

blind spot

area where axons of ganglion cells leave the eye

bipolar cells

receive input from receptor cells (rods and cones)

ganglion cells

receive input from bipolar cells

dark adaptation

increased sensitivity of rods and cones in darkness

the visual cortex

The visual processing areas of cortex in the occipital and temporal lobes.

light adaptation

decreased sensitivity of rods and cones in bright light

afterimage

sensory experience that occurs after a visual stimulus has been removed

transduction takes place in...

the rods and cones

perceptual adaptation

in vision, the ability to adjust to an artificially displaced or even inverted visual field

hue

colors (red, green, etc)

saturation

vividness of a hue

brightness

how close it is to the color white

Wavelength

Horizontal distance between waves (hue/color)

Frequency

the number of complete wavelengths that pass a point in a given time

long wavelength

red colors (low frequency)

short wavelength

blue/purple colors (high frequency)

Amplitude

Height of a wave (intensity/brightness)

large amplitude

bright colors

small amplitude

dull colors

pinna

outer ear, collects sound waves

auditory cortex

the area of the temporal lobe responsible for processing sound information

tympanic membrane (eardrum)

vibrates in response to sound waves

hammer/anvil

concentrates vibrations from the tympanic membrane

stirrup

sends concentrated vibration to the cochlea

stapes, incus, malleus

ossicles (protect or amplify certain sounds)

cochlea

a coiled, bony, fluid-filled tube in the inner ear through which sound waves trigger nerve impulses

oval window

receives vibration from stirrup

basilar membrane

Membrane in the cochlea which contains receptor cells, called hair cells

Organ of Corti

Center part of the cochlea, containing hair cells, canals, and membranes

hair cells in ear

receptor cells that turn (sound) energy of movement into neural impulses

auditory nerve

connection from ear to brain that provide information to both sides of the brain

sound localization

-use both monaural (1) and binaural (2) cues

-louder sounds are closer

-sounds will arrive at one ear sooner than the other to help determine the direction the sound is coming from

conduction deafness

ossicals are effected (physical damage, uses hearing aids)

sensorineural (nerve) deafness

problems with transduction/nerve sending message to the brain (uses cochlear implant)

place theory

Pitch is determined by location of vibration along the basilar membrane

Frequency theory

pitch is determined by frequency of hair cells produce action potentials

volley principle

pattern of sequential firing determines pitch

sound waves

changes in pressure caused by molecules of air moving

frequency

the number of complete wavelengths that pass a point in a given time (determines pitch and is measured in hertz)

Amplitude

Height of a wave, determines loudness (measured in decibels)

overtones

multiples of the basic tones

timbre

quality of texture of sound

The sense of touch

starts when something touchs your skin ->travels along sensory nerves connecting to the spinal cord ->signal sent to somatosensory cortex

somatosensory cortex

registers and processes body touch and movement sensations

transduction in touch

sensory receptor within the skin that turns the touch into electrical receptor sending it to the brain

phantom pain

pain or discomfort felt in an amputated limb

gate control theory

neurological "gate" in spinal cord which controls transmission of pain to brain

vestibular sense

the sense of body movement and position, including the sense of balance

semicircular canals in vestibular sense

provide information about equilibrium and body position

kinesthetic sense

sense of the location of body parts in relation to the ground and each other (allows coordination of body parts)

olfactory sense

sense of smell

anosmia

complete loss of smell

pheromones

used by animals for communication, provides information about identity

gustatory sense

sense of taste

taste buds (taste cells)

the organ of taste transduction (dissolve in saliva and activate receptors sent to the parietal lobe)

Supertasters/Nontasters

There are both people who experience the sense of taste with far greater intensity than average, and those who cannot sense taste at all.

synesthesia

describing one kind of sensation in terms of another ("a loud color", "a sweet sound")