unit 3 sensations & perception

Question 1

transduction

Answer 1

process that stimuli received by our sensory organs go through
- signals are transformed into neural impulses
- neural impulses travel first to thalamus then to different cortices of brain (exception: smell)

Question 2

sensory adaptation

Answer 2

decreasing responsiveness to stimuli due to constant stimulation

Question 3

sensory habituation

Answer 3

perception of sensations due to how focused we are on them
- what we perceive depends on what sensations activate our senses & by what we focus on perceiving voluntarily/involuntarily

Question 4

sensation

Answer 4

activation of senses (e.g. ears, eyes…)

Question 5

perception

Answer 5

process of understanding sensations

Question 6

vision (energy sense) - 1. light is reflected off objects & gathered by eye

Answer 6

color perceived depends on
- light intensity: determines how bright object appears
- light wavelength: determines particular hue we see (red-longest, violet-shortest)

Question 7

vision (energy sense) - 2. within eye

Answer 7

1) reflected light enters eye thru cornea
2) light goes thru pupil: iris (=muscle that controls pupil) open it (=dilate) to let more light in & close to let less light in
3) accommodation: light that enters pupil is focused my lens, image gets upside down & inverted
4) focused inverted image projects on retina where there are specialized neurons activated by different wavelengths of light

Question 8

vision (energy sense) - 3. transduction

Answer 8

translation of incoming stimuli to neural signals occurs when light activates neurons in retina (has several layers of cells)
- 1st layer: directly activated by light
- cones: cells activated by color, concentrated in center
- rods: cells respond to black/white, distributed throughout retina
-> more rods than cones
- fovea (indentation) @ v center of retina: contains highest conc of cones
- 2nd layer: bipolar cells
- next layer: ganglion cells activated when enough bipolar cells fire
- optic nerve: made up by axons of ganglion cells, sends impulses to lateral geniculate nucleus (LGN) in thalamus
-> messages sent to visual cortices @ occipital lobe
- blind spot: where optic nerve leaves retina so no rods&cones
- optic nerve is divided into 2 parts: impulses from left side of each retina go to left hemisphere…, optic chiasm=spot where nerves cross each other

Question 9

vision (energy sense) - 4. in the brain

Answer 9

visual cortex @ occipital lobe receives impulses from retina cells that activate feature detectors
- David Habel & Torsten Wiesel) discovered that groups of neurons in visual cortex respond to diff types of visual message, what we perceive visually is combination

Question 10

trichromatic theory - theory of color vision

Answer 10

3 types of cones in retina that detect red/green/blue
- cones are activated in diff combinations to produce all colors
- can’t explain some visual phenomena:
- afterimage: staring @ one color for a while then looking @ white/blank space -> color afteriamge
- colorblindness: dichromatic - can’t see red/green or blue/yellow shades // monochromatic - only see shades of grey

Question 11

opponent-process theory - theory of color vision

Answer 11

sensory receptors arranged in retina come in pairs: red/green, yellow/blue and black/white pairs
- when one sensor is stimulated, its pair is inhibited from firing
- explains color afterimage: if u stare @ red for while, you fatigue sensors for red & opponent part of pair for red fires when looking @ blank wall -> sees green afterimage
- explains color blindness: individuals missing one pair has difficulty seeing those hues

Question 12

hearing (energy sense)

Answer 12

sound waves: vibration in air NOT electromagnetic waves
- created by vibrations that travel through air -> are connected by ears -> go through transduction into neural messages & sent to brain
- has amplitude & frequency
- amplitude: determines loudness
- frequency: determines pitch (high pitched=high frequency)

Question 13

process of hearing (energy sense)

Answer 13

1) sound waves collected in outer ear (pinna)
2) waves travel down auditory canal until they reach eardrum (tympanic membrane) - vibrates
- eardrum is attached to ossicles (3 small bones): eardrum connects to hammer(malleus) which connects to anvil(incus) which connects to stirrup(stapes)
3) vibration of eardrum transmitted by these 3 bones to oval window which is attached to cochlea (snail’s shell shape w/ fluid)
- as oval window vibrates, fluid moves
- floor of cochlea = basilar membrane (covered w/ hair cells connected to organ of corti - neurons activated by hair cell movements)
-> fluid moves -> hair cells move & transduction occurs -> organ of corti fires & impulses transmitted to brain via auditory nerve

Question 14

place theory - pitch theory

Answer 14

hair cells in cochlea respond to diff frequencies of sound based on their location in cochlea -> move in diff places

Question 15

frequency theory - pitch theory

Answer 15

hair cells fire @ diff rates (frequencies) in cochlea
- lower tones: sensed by rate that cells fire
- accurately describes how hair cells sense upper range of pitches but not lower tones

Question 16

deafness

Answer 16

• conductive deafness: smth wrong w/ system of conducting sound to cochlea
• nerve (sensorineural) deafness: hair cells in cochlea are damaged (usually by loud noise), they don’t regenerate

Question 17

touch

Answer 17

brain interprets amount of indentation/temp change as intensity of touch (some nerve endings in skin respond to pressure, some to temp)
- when stimulated sharply) pain receptors fire
- grate-control theory: some pain messages have higher priority than others
- high priority -> gate swings open for it
- low priority -> gate swings shut -> doesn’t feel it
- endorphins (pain-killing): swings body shut, natural endorphins in brain control pain

Question 18

taste (gustation) - chemical sense

Answer 18

taste buds: absorb chemicals from food
- located on papillae (bumps on tongue)
- located all over tongue
- more densely packed = more chemical absorbed, more intensively food tastes

humans sense 5 types of tastes: sweet, salty, sour, bitter, umami (savory)
- some taste buds respond more intensively to specific taste
- flavor of food = combination of taste & smell

Question 19

smell (olfaction) - chemical sense

Answer 19

molecules rise to air, some drawn to nose -> molecules settle in mucous membrane @ top of nostril & absorbed by receptor cells there
- receptor cells are linked to olfactory bulb which gathers messages from olfactory receptor cells & sends info to brain
- impulses from other senses go through thalamus first before cortex BUT smell impulses go directly to amygdala (emotional) than to hippocampus (memory)
-> this direct connection to limbic system may explain why smell is powerful trigger for memory

Question 20

vestibular senses - body position sense

Answer 20

how body is oriented in space
3 semicircular canals in inner ear give brain feedback about body orientation:
- canals: tubes partially filled w/ fluid
- position of head changes -> fluid moves -> sensors in canals move
- movement of hair cells activate neurons -> impulse goes to brain

Question 21

kinesthetic sense - body position sense

Answer 21

feedback about position & orientation of specific body part
- receptors in muscle & joints send info to brain about limbs -> info + visual feedback lets us keep track of body

Question 22

perception

Answer 22

process of understanding & interpreting sensations
- psychophysics: study of interaction btwn sensations we receive & our experiences of them

Question 23

threshold

Answer 23

absolute threshold: smallest amount of stimulus we can detect
- of vision: smallest amount of light we can detect
- minimal amount of stimulus we can detect 50% of time
- subliminal: stimulus below absolute threshold

different threshold: smallest amount of change needed in stimulus before we detect change
- Weber’s law: change needed is proportional to original intensity of stimulus
- more intense stimulus, more it needs to change before we notice difference

Question 24

signal detection theory - perceptual theory

Answer 24

• investigates effects of interference we experience while perceiving
• tries to predict what we’ll perceive among competing stimuli
• response criteria (receiver operating characteristics): how motivated we are to detect certain certain stimuli & what we expect to perceive
• false positive: we think we received a stimulus that’s not there
• false negative: not perceiving a stimulus that’s present

Question 25

top-down processing - perceptual theory

Answer 25

we perceive by filling in gaps in what we sense
- occurs when using background knowledge
- schemata: mental representations of how we expect the world to be (created by experience)
- creates perceptual set: predisposition to perceiving smth in certain way
- faster but more prone to error

Question 26

bottom-up processing (feature analysis) - perceptual theory

Answer 26

only use features of object itself to build a complete perception
- takes longer but more accurate

Question 27

figure-ground relationship - principles of visual perception

Answer 27

determines what part is figure and what part is background

Question 28

gestalt rules - principles of visual perception

Answer 28

we perceive image as groups, not as isolated elements (innate & inevitable)

factors influencing how we group objects:
- proximity: objects close together -> same group
- similarity: objects similar in appearance -> same group
- continuity: objects arranged in continuous line or curve -> same group
- closure: objects that make up a recognizable image -> same group

Question 29

constancy - principles of visual perception

Answer 29

ability to maintain constant perception of object despite changes
- size constancy: we take distance into account in estimations of size -> keep a constant size in mind for an object
- shape constancy: object views from diff angles -> still knows shape of object remains constant
- brightness constancy: objects being constant color even as light reflecting off object changes

Question 30

perceived motion

Answer 30

brain detects how fast images move
- stroboscopic effect: brain perceives objects to be moving when they aren’t (e.g. movies)
- phi phenomenon: series of lightbulbs turned on & off @ particular rate will appear to be one moving light
- autokinetic effect: ppl report seeing spot of light in same place moving when staring at it

Question 31

depth cues

Answer 31

Eleanor Gibson) visual cliff experiment to determine when human infants can perceive depth
- other experiments: depth perception develops about three months old

cues we use to perceive depth: monocular cues
(not depend on having 2 eyes) // binocular cues (depend on having 2 eyes)

Question 32

monocular cues

Answer 32

• linear perspective: two lines converge @ top of paper to show distance
• relative size cue: objects closer as larger
• interposition cue: objects that block view of other objects must be closer to us
• texture gradient: closer objects w/ more details
• shadowing: implys where light source is -> imply depth & position of objects

Question 33

binocular cues

Answer 33

• binocular disparity (retinal disparity): each of our eyes sees any object from slightly different angle -> closer the object, more disparity there will be btwn images coming from each eye
• convergence: as object gets closer, eyes must move toward each other to keep focus

Question 34

effect of culture on perception

Answer 34

some perceptual sets are learned from culture

Question 35

extrasensory perception (ESP)

Answer 35

perceiving sensation “outside” senses
- skeptical