HP1000 Lecture 3: Sensation & Perception

cortex in parietal lobe

primary somatosensory cortex

cortex in occipital lobe

primary visual cortex

cortex in temporal lobe

primary auditory cortex

cortex in frontal lobe

prefrontal cortex

taste cortex

gustatory cortex

smell cortex

olfactory cortex

synaesthesia: definition

sense information being interpreted as more than one sensation

McGurk Effect

what we see overrides what we hear

transduction: definition

converting outside stimuli into neural activity

sensation: definition

converting outside stimuli into neural signals in the brain via transduction

perception: definition

interpretation and organisation of senses in some meaningful fashion

habituation: definition

tendency of the brain to stop attending to constant, unchanging information at the level of PERCEPTION

habituation: example

filtering out sound of a fan

sensory adaptation: definition

tendency of sensory receptor cells to become less responsive to an unchanging stimulus at the level of SENSATION

sensory adaptation: example

swimming in cold water

absolute threshold: definition

smallest amount of energy needed for someone to consciously detect a stimulus 50% of the time it is present

absolute threshold for sight

candle flame 48km away at night

absolute threshold for hearing

watch ticking 6m away in quiet room

absolute threshold for smell

1 drop of perfume diffused in a 3-room apartment

absolute threshold for taste

1 tsp of sugar in 7.6l of water

absolute threshold for touch

bee’s wing falling on cheek from 1cm above

Just Noticeable Difference (JND) / Difference Threshold: definition

smallest difference or change between 2 stimuli that is detectable 50% of the time

law regarding thresholds

Weber’s Law

Weber’s Law: definition

the size of the difference threshold is proportional to the intensity of the initial stimulus

VISION: Layer 1 in the eye

retina

retina: function

converts incoming light to nerve impulses

retina: contains ____ cells

photoreceptor

central area of retina

fovea

fovea: function

where light rays are most sharply focused

fovea: greatest density of ____

cones

eye layer 3

blind spot

blind spot: also known as

optic disc

blind spot / optic disc: function

where optic nerve leaves the eye

eye layer 4

optic nerve

optic nerve: function

transmits visual information from retina to the brain

transduction in vision: neural pathway

retina → optic nerve → optic chiasm → optic tract → thalamus → primary visual cortex

retina layer 1

ganglion cells

ganglion cells: function

bundled axons form optic nerve

retina layer 2

bipolar cells

bipolar cells: function

relay information

2 kinds of photoreceptors in retina

rods and cones

rods: responsible for

night vision

cones: responsible for

colour, sharpness of vision

light waves: visible light to humans on EM spectrum

400-700nm

less than 400nm: colour

violet

400nm colour

blue

500nm colour

green

600nm colour

yellow

700nm colour

red

wavelength for blue

400nm

wavelength for green

500nm

wavelength for yellow

600nm

wavelength for red

700nm

amplitude of light wave is perceived as

brightness

wavelength of light wave is perceived as

colour

purity of light wave is perceived as

saturation

first theory of colour perception

trichromatic (three colours) theory (RGB)

trichromatic (three colours) theory: proposes ____

we have 3 types of cones (RGB)

second colour perception theory

opponent-process theory

opponent-process theory proposes _____

4 primary colours arranged in opponent pairs beyond the cones

colour-deficient vision: 2 types

monochromatic and dichromatic

monochromatic vision: condition where _____

2 or 3 cones do not work properly

dichromatic vision: condition where ____

one cone does not work properly

HEARING: physical pathway

sound waves → eardrum → hammer - anvil - stirrup → cochlea → auditory nerve

HEARING: neural pathway

cochlea → auditory nerve → thalamus → primary auditory cortex

sound waves cause ____ to vibrate

eardrum

eardrum vibrating causes _____ to vibrate

hammer, anvil, stirrup

when hammer, anvil, stirrup vibrate → ______ sound

amplify

what is suspended in the fluid within cochlea

basilar membrane

basilar membrane contains ________

organ of corti (hair cells)

organ of corti are bent by ___________, [function]

mechanical vibrations in cochlear fluid, decide whether to fire neural signals to auditory cortex for processing

transduction in hearing: 2 theories

place theory and frequency theory

place theory

theory of pitch that states that different pitches are experienced by stimulation of hair cells in different locations on organ of corti

frequency theory

theory of pitch that states that pitch is related to the speed of vibrations in the basilar membrane

soundwaves: amplitude is perceived as ______

loudness

soundwaves: frequency is perceived as ______

pitch

soundwaves: complexity/purity is perceived as ______

timbre

smell: olfactory bulb (location)

just below frontal lobe

olfaction: physical and neural pathway

odour molecules → cilia → olfactory receptor cell → olfactory nerves → olfactory bulb → primary olfactory cortex and amygdala

olfaction: why unlike other senses

direct path to amygdala instead of thalamus

transduction in taste

taste bud → gustatory hair in taste pore → gustatory cell → thalamus → primary gustatory cortex and amygdala

5 primary tastes

sweet, sour, bitter, salty, umami

additional taste

oleogustus (taste of fat)

sense of touch is called ____

somesthetic senses

Somesthetic senses: The body senses consisting ____, _____ & ______

skin senses, kinesthetic sense, vestibular sense

skin senses: function

transduce signals about touch, pressure, temperature, pain through nerve endings

skin senses: neural pathway

skin → spinal cord → primary somatosensory cortex and limbic system

kinesthetic sense: 2 parts

kinesthesia and proprioception

kinesthesia: definition

awareness of body movement (how much to move, in what direction)

proprioception: definition

awareness of where the body and body parts are located in relation to each other in space and to the ground

vestibular sense: related to ______

proprioception

vestibular sense: definition

awareness of balance, posture, position, movement of the head and body through space in relation to gravity’s pull

vestibular sense: responsible for

motion sickness

theory relating to vestibular sense

sensory conflict theory

sensory conflict theory

when visual information from the eyes conflicts with information from the vestibular senses

vestibular sense is processed by _______ in the _____, particularly the ______

vestibular organs in the inner ear, particularly the semicircular canals

vestibular sense neural signal pathway

semicircular canals → vestibular nerve → parietal cortex

Perception: what theory

Gestalt theory

Gestalt Theory: proposes that ___

the brain forms a perceptual whole that is more than the sum of its parts

Gestalt theory: nature or nurture

nature