Unit 3 Sensation and Perception

sensation

the process by which our sensory receptors and nervous system receive stimulus from the environment

perception

the process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events

TOP + UP

brain (processing)

BOTTOM + DOWN

senses (experience w/senses)

TOP DOWN processing

information processing guided by higher-level mental processes, as when we construct perceptions drawing on our experience and expectations

BOTTOM UP processing

analysis that begins with the sensory receptors and works up to the brain’s integration of sensory information

psychophysics

relationship between physical stimuli and our psychological experience to them

absolute threshold

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

difference threshold or noticeable difference

the minimum difference that a person can detect between two stimuli

weber’s law

the idea that, to perceive a difference between two stimuli, they must differ by a constant percentage; not a constant amount

signal detection theory

predicts how we detect a stimulus amid other stimuli, assumes that we do not have an absolute threshold, and we detect stuff based on our experiences, motivations, and fatigue level

subliminal stimulation

below one’s absolute threshold for conscious awareness

sensory adaptation

diminished sensitivity as a result of constant stimulation (applies to all of our senses)

selective attention

the focusing of conscious awareness on a particular stimulus

cocktail party effect

ability to listen to one voice among many

sensory receptors

sensory nerve endings that respond to stimuli

inattentional blindness

failing to see visible objects when our attention is directed elsewhere

change blindness

failing to notice changes in the environment; a form of inattentional blindness

transduction

conversion of one form of energy into another, in sensation, the transforming of stimuli energies such as sights, sounds, and smells, into neural impulses our brain can interpret

Gustav Fechner

studied the edge of our awareness; absolute thresholds

subliminal

below one’s absolute threshold for conscious awareness

Ennst Weber

created and described Weber’s law

priming

the activation, often unconsciously, of certain associations, thus predisposing one’s perception, memory, or response

perceptual set

a mental predisposition to perceive one thing and not another context, motivation, and emotion affects our interpretations

extrasensory perception (ESP)

the controversial claim that perception can occur apart from sensory input; includes telepathy, clairvoyance, and precognition

telepathy

mind-to-mind communication

clairvoygance

perceiving remote events, such as a house fire in another state

precognition

perceiving future events, such as an unexpected death in the next month

phrapsychology

the study of paranormal phenomena, including ESP and psychokinesis

wavelength

the distance from the peak of one light or sound wave to the peak of the next

short wavelength

high frequency (bluish colors, high-pitched sounds)

long wavelength

low frequency (reddish colors, low-pitched sounds)

hue

the dimension of color that is determined by the wavelength of light

intensity

the amount of energy in a light wave or sound wave, which influences what we perceive as brightness or loudness; determined by the wave’s amplitude (height)

great amplitude

bright colors, loud sounds

small amplitude

dull colors, soft sounds

cornea

the eye’s clear, protective outer layer, covering the pupil and iris

pupil

the adjustable opening in the center of the eye through which light enters

iris

a ring of muscle tissue that forms the colored portion of the eye

lens

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

retina

the light-sensitive inner surface of the eye, containing the receptor rods and cones plus layers of neurons that begin with the processing of visual information

accommondation

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

rods

retinal receptors that detect black, white, and gray, and are sensitive to movement; necessary for peripheral and twilight vision, when cones don’t respond

cones

retinal receptors that are concentrated near the center of the retina and that function in daylight or in well-lit conditions; detect fine detail and give rise to color sensations

optic nerve

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

blind spot

the point at which the optic nerve leaves the eye, creating a “blind” spot because no receptor cells are located there

fovea

the central focal point in the retina, around which the eye’s cones cluster

Young-Helmnoltz trichromatic (three-color) theory

the theory that the retina contains 3 different types of color receptors - one most sensitive to red, one to green, one to blue - which when stimulated in combination, can produce the perception of any color

opponent-process theory

the theory that opposing retinal processes (red-green, blue-yellow, white-black) enable color vision (we cannot see certain colors together)

feature detectors

nerve cells in the brain’s visual cortex that respond to specific features of the stimulus, such as shape, angle, or movement

parallel processing

processing many aspects of a problem simultaneously; the brain’’s natural mode of information processing for many functions (allows us to notice color, motion, form, depth)

David Hubel and Torsten Wiesel

showed that our visual processing deconstructs visual images then reassembles them

gestalt

an organized whole; Gestalt psychologists emphasized our tendency to integrate pieces of information into meaningful wholes

figure-ground

the organization of the visual field into objects (the figures) that stand out from their surrondings (the ground)

grouping

the perceptual tendency to organize stimuli into conveint groups

proximity

we group nearby figures together

continuity

we perceive smooth, continuous patterns rather than discountinous ones

closure

we fill in gaps to create a complete, whole object

depth perception

the ability to see objects in 3 dimensions although the images that strike the retina are two-dimensional; allows us to judge distance

visual cliff

a laboratory device for testing depth perception in infants and young animals

binocular cue

a depth cue, such as retinal disparity, that depends on the use of 2 eyes

retinal disparity

a binocular cue for perceiving depth by comparing retinal images from the 2 eyes, the brain computes distance - the greater the disparity between the 2 images, the closer the object

monocular cue

a depth cue, such as interposition or linear perspective, available to either eye alone

examples of monocular cues

interposition, relative size, relative clarity, texture gradient, relative height, relative motion, linear perspective, and line and shadow

phi phenomenon

an illusion of movement created when 2 or more adjacent lights blink on and off in quick succession

perceptual constancy

perceiving objects as unchanging (having consistent color, brightness, shape, and size) even as illumination and retinal images change

color constancy

perceiving familiar objects as having consistent color, even if changing illumination alters the wavelengths reflected by the object

Immanuel Kant

maintained that knowledge comes from our inborn ways of organizing sensory experiences

John Locke

argued that through our experiences we also learn to perceive the world

perceptual adaptation

the ability to adjust to changed sensory input, including an artificially displaced or even inverted visual field

audition

the sense or act of hearing

frequency

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

pitch

a ton'e’s experienced highness or lowness; depends on frequency

middle ear

the chamber between the eardrum and cochlea containing 3 tiny bones (hammer, anvil, and stirrup) that concentrate the vibrations of the eardrum on the cochlea’s oval window

cochlea

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

inner ear

the innermost part of the ear, containing the cochlea, semicircular canals, and vestibular sacs

sensorineural hearing loss

hearing loss caused by damage to the cochlea’s receptor cells or to the auditory nerves; most common form of hearing loss, also called nerve deafness

conduction hearing loss

less common form of hearing loss, caused by damage to the mechanical system that conducts sound waves to the cochlea (due to constant exposure to sounds greater than 85 decibels)

cochlear implant

a device for converting sounds into electrical signals and stimulating the auditory nerve through electrodes threaded into the cochlea

place theory

in hearing, the theory that links the pitch we hear w/ the place where the cochlea’s membrane is stimulated (we hear different pitches because different sound waves trigger activity at different places along the cochlea’s basilar membrane)

frequency theory

in hearing, the theory that the rate of nerve impulses traveling up the auditory nerve matches the frequency of a tones thus enabling us to sense its pitch; also called temporal theory (has trouble explaining high pitches sounds because our hairs cannot vibrate at certain speeds)

4 basic senses of skin

pressure, warmth, cold, and pain

pain reflects…

bottom-up sensations and top-down cognition

nociceptors

detect hurtful temperatures, pressure, and chemicals; found in skin, muscles, and organs

gate-control theory

theory that the spinal cord contains a neurological “gate” that blocks pain signals or allows them to pass on to the brain; the gate is opened by the activity of pain signals traveling up small nerve fibers and is closed by activity in larger fibers or by information coming from the brain

Ronald Melzack and Patrick Wall

proposed the gate control theory

gustation

our sense of taste

5 specific tastes

sweet, salty, sour, bitter, and umami

sweet

energy source

salty

sodium essential to physiological processes

sour

potentially toxic acid

bitter

potential poisons

umami

proteins to grow and repair tissue

olfaction

the sense of smell

kinesthesia

our movement sense - our system for sensing the position and movement of individual body arts

vestibular sense

our sense of body movement and position that enables our sense of balance

sensory interactions

the principle that one sense may influence another, as when the smell of food influences its taste

embodied cognition

the influence of bodily sensations, gestures, and other states on cognitive preferences and judgements

source, receptors, and brain area in vision

light waves striking the eye, rods and cones in the retina, occipital lobes

source, receptors, and brain area in hearing

sound waves striking the outer ear, cochlear hair cells (cilia) in the inner ear, temporal lobes