Sensation and Perception

sensation

process of taking in information from the environment

perception

the way we recognize, interpret, and organize our sensations

psychophysics

branch of psychology that deals with the effects of physical stimuli on sensory response

absolute threshold

minimum amount of stimulation needed to detect a stimulus and cause the neuron to fire 50 percent of the time

detection threshold

same as absolute threshold

Gustav Fechner

founder of psychophysics

typical absolute threshold experiment

playing series of tones of varying volume to determine what volume the participant first reports hearing the tone

signal detection theory

four possibilities of a detection trial, takes into account bias, moods, feelings

discrimination threshold

the point which one can distinguish the difference between two stimuli

just noticeable difference (JND)

minimum amount of distance between two stimuli to be detected as distinct

difference threshold

same as just noticeable difference

Ernst Weber

Weber’s law

Weber’s law

JND is a proportion of stimulus intensity, the greater the stimulus, the larger the difference must be to notice

subliminal perception

form of preconscious processing that we are not consciously aware of them

priming

preconscious processing

tip of the tongue phenomenon

recalling something that we know is available but it isn’t easily available for conscious awareness

specialized cells in sensory organs

receptor cells

receptor cells

designed to detect specific types of energy

receptive field

the area from which receptor cells receive input

transduction

process in which receptors convert stimuli into neural impulses

thalamus function in receiving input

redirects sensory information, filters out some inputsc

contralateral shift

sensory input from one side of the body traveling to the opposite side of the brain

sensory coding

the process by which receptors convey the wide range of input to the brain

qualitative dimension

coded and expressed by which neurons are firing

quantitative dimension

coded by the number of cels firing

single cell recording

a technique by which the firing rate and pattern of a single receptor cell can be measured in response to varying sensory input

visual sensation

occurs when the eye receives light input from the outside world

distal stimulus

the object as it exists in the environment

proximal stimulus

the image of the object on the retina

cornea

protective layer on the outside of the eye

lens

under the cornea, curvature changes to accommodate for distance

accommodations

changes in the curvature of the lens to accommodate for distance

retina

back of the eye, screen onto which the proximal stimulus is projected, covered with rods and cones

rods

periphery of the retina, sensitive in low light

cones

center of the retina, sensitive to bright light and color vision

fovea

center of the retina

bipolar and amacrine cells

passed here after receptors, low level processing

optic nerves

send information to the brain

blind spot

the spot where the optic nerve exits the retina

optic chasm

where the optic nerves cross

serial processing

when the brain processes information step by step

parallel processing

when the brain computes multiple pieces of information simultaneously

vision processing type

parallel processing

feature detector neurons

“see” different parts of the pattern

convergence

the process by which information becomes more complex as it travels through the sensory system

ventral stream

connects to the prefrontal cortex, allows recognition of an object

dorsal stream

connects to the somatosensory cortex, integrates visual information with the other senses

David Hubel and Torsten Wiesel

experiments with cats, mammals will develop normal vision as long as impairments are corrected during the critical period

critical period

the first months after birth which vision impairments can be corrected

Young-Helmholtz trichromatic theory

colors are made from a mix of blue, red, and green

opponent process theory

thalamus responds to pairs of colors, if one is on, the other is off

opponent process theory color sets

black and white, red and green, blue and yellow

afterimage

opposite color receptors are more active after the others have become fatigued

color blindness

mostly occurs in males, sex-linked genetic condition

dichromats

inability to distinguish along the red/green or blue/yellow continuums

monochromats

see only in shades of black and white

auditory input

sound waves

outer ear

sound waves enter here, outside of head, collects and magnifies sound waves

ear canal

inner part of outer ear

middle ear composed of

tympanic membrane, ossicles

tympanic membrane

eardrum, first vibrated in middle ear

ossicles composed of

malleus, incus, stapes

ossicles

vibrated by eardrum, vibrato against the oval window

inner ear composed of

oval window, cochlea, basilar membrane, vestibular sacs, auditory nerve

oval window

beginning of inner ear, vibrate against cochlea

cochlea

contain receptor cells

hair cells

auditory receptor cells in the cochlea along the basilar membrane

basilar membrane

structure where hair cells are lined on

auditory nerve

receives sound energy from cochlea, transmits to temporal lobe

vestibular sacs

responsible for balance, receptors sensitive to tilting

Georg von Bekesy

traveling wave energizes the basilar membrane, higher frequencies have higher travel wave peaks

place theory

sound waves cause activity at different places along the basilar membrane

frequency theory

rate of neural impulses equals the frequency of a particular sound, pitch

deafness

can occur from damage to the ear structure or the neural pathway

conductive deafness

injury to the outer or middle ear structures

sensorineural (nerve) deafness

injury to inner ear

hearing aids

addresses conductive and milder forms of sensorineural deafness

cochlear implant

addresses profound sensorineural deafness

olfaction

smell, chemical sense, olfactory epithelium

gustation

taste, chemical sense, taste buds on papillae on tongue

5 basic tastes

sweet, salty, bitter, sour, unami (savory)

cutaneous and tactile receptors

skin, provides information about pressure, pain, and temperature

cold fibers

fire in response to cold stimuli

warm fibers

fire in response to warm stimuli

vestibular sense

sensation of balance, found in ear

kinesthesis

location and position of the limbs and body parts, found in joints and ligaments

synesthesia

stimulation of one sense leading to automatic activation of another

dynamic feature of senses

ability to detect changes in stimulus intensity and quality

adaptation

unconscious, temporary change in response to environmental stimuli, example: seeing in the dark

habituation

accustomation to a stimulus over time, can be conscious

dishabituation

change in stimulus causes us to notice it after it was habituated

attention

focusing on one aspect of our perceptual world

selective attention

paying attention to one thing while ignoring another

cocktail party phenomenon

being able to hear your name in a room full of conversations

shadowing

repeating something played in one ear while ignoring the other ear

filter theories

stimuli must pass through some form of screen or filter to enter into attention

attentional resource theories

fixed amount of attention, divided up as required

divided attention

trying to focus on more than one task at a time

inattention blindness / change blindness

focusing too intently on a specific stimuli, missing the bigger picture

perceptual processes

how the mind interprets stimuli