Unit 4 Sensation and Perception

Sensation

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

perception

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

bottom-up processing

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

top-down processing

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

selective attention

the focusing of conscious awareness on a particular stimulus

inattential blindness

failing to see visible objects when our attention is directed elsewhere

change blindness

failing to notice changes in the environment, man switch behind door -man giving directions doesn’t notice the man changed

transduction

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

absolute threshold

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

priming

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

difference threshold

the minimum difference between 2 stimuli required for detection 50% of the time. we experience the difference threshold as a just noticable difference (jnd)

weber’s law

the principle that, to be perceived as different, 2 stimuli must differ by a constant minimum % (rather than a constant amount)

sensory adaptation

diminished sensitivity as a consequence of constant stimulation

psychophysics

the study of relationships between the physical characteristics of stimuli, such as their intensities, and our psychological experience of them

subliminal

below one’s absolute threshold for conscious awareness

wavelength

the distance from the peak of one light or sound wave to the peak of the next. electromagnetic wavelengths vary from the short blips of cosmic rays to the long pulses of radio transmission

intensity/amplitude

the amount of energy in a light or sound wave, which we perceive as brightness or loudness, as determined by the wave’s output

long/low-frequency wavelength=

light- red hue

sound- low pitch

wavelength=

hue and pitch

short/high-frequency wavelength

light- blue hue

sound- high pitch

short amplitude

light- dim

sound- quiet

tall amplitude

light- vibrant

sound- loud

amplitude

saturation/brightness and volume

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 around the pupil and controls the size of the pupil opening

locate all of the terms

eye diagram

lens

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

mnemonic for eye structure

can people in london read french? really cool brits give other nations (cornea pupil iris lens retina fovea rods cones bipolar cells ganglion cells optic nerve -thalamus occipital lobe visual cortex)

retina

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

where does transduction occur in the eye

retina

accomodation

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

rods

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

cones

retinal receptor cells that are concentrated near the center of the retina (close to the fovea) and that function in daylight or in well-lit conditions. the cones detect finer details and give rise to color sensations

fovea

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

blind spot

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

feature detectors

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

cocktail party effect

ability to attend to one voice among a sea of others (being able to hear your name being said no matter how quiet or far away)

choice blindness

being unaware of choices made; usually by not paying attention (and the brain makes up a reason) - order something and given another thing but you didnt notice so you think you actually did order it

cornea

eye’s clear, protective outer layer

sensory adaptation allows us to

focus on more important things/changes in the environment (biological process- can’t prevent it)

nearsightedness

eyeball is abnormally long, focal point of light occurs in front of retina (myopia)

farsightedness

eyeball is abnormally skinny, light never gets focused by the time it reaches retina (hyperopia)

bipolar cells

neurons transport from the retina into the bipolar cells which then transport it to the ganglion cells

ganglion cells

connected to the bipolar cells and neurons get transported through it, ganglion cells intertwine to turn into the optic nerve

optic nerve

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

young-helmholtz trichromatic theory

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

parallel processing

the processing of many aspects of a problem simultaneously; the brains natural mode of info-processing for many functions (like vision)

opponent-process theory

the theory that opposing retinal processes (red-green, yellow-blue, black-white) enables color vision

afterimage

our brain tires of white response, so it fires its opponent color 

(if you look at something red for a long time and then look away and blink rapidly, you will see the object in green- ex the random shape on the slides in white and black outline (looking at the white shape in the middle), look at the white slide and you blink and you see the black outline of jesus)

dichromatism

2 cones function, one not, red-green color blindness is most common-98% of all color blindness cases

monochromatism

one cone functional, two not, everything appears as shades of one color, very rare

frequency

the number of complete wavelengths that pass a point at a certain time

pitch

a tone’s experienced highness or lowness, depends on frequency

middle ear

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

cochlea

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

pinna

external part of your ear, funnels sound into ear canal

ear canal

channels sounds toward ear drum (tympanic membrane)

eardrum (tympanic membrane)

tight membrane in outer ear, starts hearing process

oval window

cochlea’s membrane covered opening

basilar membrane

stiff inner structure of the cochlea, contains hair cells, hair bends, transduction occurs

auditory nerve

carries neural message to thalamus, then auditory cortex

semicircular canals

contains fluid to help our body sense movement and balance

vestibular sacs

contains calcium crystals that send information to cerebellum about balance

cochlear implant

converts sound into electrical signals and directly stimulates auditory nerve through electrodes threaded into cochlea

Sensorineural Hearing Loss/Deafness

hearing loss caused by damage to the cochlea’s receptor cells or to the auditory nerve

Conduction Hearing Loss/Deafness

hearing loss caused by damage to the mechanical system, that conducts sound waves to the cochlea

place theory

in hearing, the theory that links the pitch we hear with the place where the cochlea’s membrane is stimulated

place theory explains

high pitched sounds

frequency theory

in hearing, the theory that the rate of nerve impulses traveling up the auditory nerve matches the frequency of a tone, thus enabling us to sense its pitch

frequency theory explains

low pitched sounds

gate-control theory

the 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 nerve fibers or by information coming from the brain

gate-control theory explains the effectiveness of

acupuncture

volley principle

neurons fire in alternative bursts to account for frequencies above 1000 waves per second

nociceptors

sensory receptors that detect harmful temperatures, pressure and chemicals

phantom limb sensations

brain misinterprets spontaneous stimulation of central nervous system as sensory input, happens to amputees who lose a limb

tinnitus

ringing in ear

super taster

Higher number of tastebuds than average. Low gustatory absolute threshold. (25% of population)

medium taster

Average number of tastebuds. Average gustatory absolute threshold (50% of population)

non-taster

Lower number of tastebuds than average. High gustatory absolute threshold. (25% of population)

6 taste sensations

salty, sweet, bitter, sour, umami (savory/meaty), fatty (oleogustus)

which senses are chemical?

smell and taste

olfactory membrane

contains olfactory receptor cells in the top of each nasal cavity

olfactory nerve

formed from converging axons of the olfactory membrane

olfactory bulb

in the frontal/temporal lobes

kinesthetic sense

the system for sensing the position and movement of individual body parts

vestibular sense

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

which sense bypasses the thalamus?

smell

synesthesia

Stimulation of one sense triggers the experience of another, Brain circuitry for one sense gets wired with another (people who say music appears to them visually in shapes and colors)

perceptual set

mental predisposition to perceive one thing and not another

4 things that affect our perceptual set

context, motivation, emotion, culture

figure-ground

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

sensory interaction

the principle that 1 sense may influence another, as when the smell of food influences taste (ex: vision and hearing, yanny-v-laurel, stairway to heaven in reverse sounds like satanic worship)

gestalt

an organized whole- human tendency to integrate pieces of information into meaningful wholes

grouping

the perceptual tendency to organize stimuli into coherent groups

depth perception

the ability to see objects in 3 dimensions although the images that strike the retina are 2-dimensional; allows us to judge distance

visual cliff

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

binocular cues

depth cues, such as retinal disparity, that depend of the use of both(2) eyes

perceptual context

our immediate surroundings affect how we perceive the world

motivation

gives us energy to work toward a goal: disrupt our perceptions (desirable objects appear closer than they are, water bottle for a thirsty person (energizes us to work toward it))

Muller Lyer Illusion

optical illusion, lines are same length but people think the second is longer because the branching lines are extending out