sensation
stimulation of sense organs
perception
interpretation of sensory input
psychophysics
how physical stimuli are translated into psychological experience (used to measure threshold)
gustav fechner
discovered the concept of threshold
absolute threshold
minimal amount of stimulus that can be detected 50% of the time
threshold
at what point do we detect stimulus
JND
smallest difference detectable between 2 stimuli
Websters Law
Size of JND is proportional to size of original stimulus ex: 30-31, 60-62 etc
signal detection theory
detection of sensory information is influenced by sensory processes and decision processes– hit, false alarm, miss, correct rejection
“hit”
stimulus present and subjects response is present
miss
stimulus present but subject response is absent
absent
stimulus is absent but subject believes it is present
correct rejection
stimulus is absent and subject believes it is absent
Perception without awareness
advertising** used to influence buyers without buyers noticing
subliminal perception
stimulus presented just beyond our threshold
sensory adaptation
stimulus is present and doesn’t change but our reaction has changed– decline in sensitivity, overtime we become less sensitive to the stimulus
synaesthesia
condition in which perceptual/cognitive activities trigger special experiences–senses overlap (ex see colour over math)
Graphemes
numbers and letters have colour
light
electromagnetic radiation
brightness of light
amplitude (height of light wave)
colour of light
wavelength, distance from one peak to the next, long-red, short-blue
purity
mixture of wavelength in the light
saturation
richness of colour, amount of whiteness in a colour impact saturation
pure vs not pure (aka saturation)
pure- one wave
not pure- a bunch of wavelength
retina
neural tissue at the back of our eye
cornea
where light waves begin to penetrate our eyes, transparent
anterior chamber,
filled with a fluid called aqueous humor, flows through canals, constantly being replaced, blockage in the canal leads to build up of pressure in the eye–> glaucoma, leads to blindness
lens
lens refract the light waves when it enters the eye, bending the light waves causes it to be flipped and backwards
little muscles relax: lens fattens, near
little muscles flex: lens becomes thin, far
vitreous humor
jelly like substance in the posterior chamber, developed as a fetus, leftover proteins are squiglys
pupil
gap, changes in size in order to control the amount of light that is let in
iris
coloured part of the eye, ring of muscle that control the contraction of pupil
fovea
dip at the back of the eye, crispest vision
saccade
tiny eye movements we are constantly making, constantly moving to fill the blind spot
nearsighted
myopia, less round, more football shape, focus point falls in front of the retina
far sighted
hyperopia, see further away, focus point behind retina
presbyopia
happens when we get older the shape of our lens does not change as much as before, begin to have problems seeing things that are close to us
photoreceptor cells
cones and rods
rods
night vision, respond well to dim lighting , more, peripheral vision, no colour information
cones
need lots of light, bright will be most active during the day, what gives us our colour vision
dark adaption
rods react to darkness and increase sensitivity
receptive fields
retinal area that affects firing of cell, ganglion is reactive to pinpricks of light
no light: action potential firing at a normal baseline
light in centre: basically turns on the cell, INCREASING firing rate
light in the surrounding: DECREASING firing rate
computer vision function
computer models function the same way our receptor fields work, to find out what kind of information we can obtain from this, at the initial level our ganglions are receiving information on where the edges are
Magnocellular
associated with ganglions that are large, cells that process information about brightness
parvocellular
tend to be smaller, process colour information
brain structures involved in vision
70 different parts of the brain involved in vision that work together (right visual field–> left brain, left visual field–> right brain)
optic chiasm
point where information splits and crosses over into either right or left hemisphere
pathway of visual information
optic nerve- optic chiasm- lateral geniculate nucleus- occipital cortex- primary visual cortex
hubel and wiesel
simple- width and orientation of lines when in right position,
complex- width and orientation when in any position
primary cortex in occipital lobe, cells do not responds to pinpricks of light but lines, complex fire in response to the bar of light in the receptor field
ventral pathway
what an object is
WHATs on TV
dorsal pathway
where an object is and how to it
WHEREs the PD
trichromatic theory- young and helmholtz
receptors 3 different photopigments(cones), sensitive to short medium or long wavelengths, different levels of neural activation translated into different colours
opponent process theory- hering
3 pairs of antagonistic colours (red/green, black/white, blue/yellow), not just three cones, we have cells that bunch in an opponent process, each cells responds to two different colours, you fatigue the part that is responding to the colour you stare at, you see the opposite colour
theory of vision
both are correct- trichromatic applies at retinal level, opponent process applies at retina( ganglion cells), LGN, and visual cortex
effects of colour on behaviour
associations between colours and experiences
adaptive value- association to the colour depends on the context
ex RED negative in academic, positive in dating situations
perceiving forms, patterns and objects
what you perceive depends on many things,
perceptual set
readiness to perceive in a particular way
inattentional blindness
failure to see visible objects or events because attention is focused elsewhere
change blindness
we often miss large changes in our visual world without notice
feature analysis
process of detecting specific (basic) elements in visual input and assemble into more complex form
gestalt theory
whole can be greater than the sum of its parts, figure (close to you) and ground (background)
distal
stimuli outside the body
proximal
stimulus energies impinging on sensory receptors, pattern of light that the distal stimulus casts on your retina, sometimes hard to recognize… context will influence
binocular cues
cues from both eyes
retinal disparity
difference between the 2 images projected on each retina
monocular cue
information from one eye
convergence
eyes turn toward each other to focus on near objects
motion parallax
depends on one eye- objects at different distances move at different rates, things that are close to you move a lot more in comparison to objects further away
accomodation
when you are focusing on something close vs far the shape of your lens has to change
pictorial cues
take advantage of pictorial cues, ex linear perspective, realtive size, texture gradiant, shadow etc
perceptual constancies
stable perceptions amid changing stimuli ex size and shape (what we are looking at is constantly changing in terms of our retina, as things change, your visual system assumes its not the case that the object has gotten bigger, just closer)
optical illusion
inexplicable discrepancy between appearance and reality (the visual system interprets the angles in certain way because of our society)
Ames room
visual system overrides what you are actually seeing, can sometimes be used in movies to fool your visual system)|_\
Hearing
amplitude and frequency (also prosody) specific mixture of sound waves will cause timbre
amplitude
dB decibels- sound pressure
frequency
Hz- cycles per second
prosody
melodic musical quality of our voices
aprosodia
someone who cant pick up on musical qualities
human hearing range
20-20000 hz
pinna
external ear, directs sound waves toward auditory canal
ear drum
piece of membrane that vibrates when they encounter sound waves
ossicles
tiny chain of bones hammer anvil and stirup
cochlea
tiny structure in inner ear, filled with fluid when the sound travels through it will lead to vibrations of the fluid
auditory nerve
axons, once neural impulse are formed they travle through the auditory nerve to the brain
basilar membrane
cilia, vibration of fluid leads to bumping or sheering of cilia they cause a neural impulse into the brain processed by the thalamus then into the auditory cortex which is in the temporal lobe, cilia do not grow back
place theory
von helmholtz 1863 high frequency sound the specific area of high frequency sound will vibrate along that specific part of the cochlea not the whole thing
Frequency theory
Rutherford 1886
we would have the cochlea firing at a frequency of the sound we are hearing
Initial hearing sound
at the base of the cochlea was higher frequency sounds and apex was lower frequency
George Von Bekesy 1947- traveling wave theory
when we bring the two thoeries together; the whole basilar membrane does vibrate but depending on specific frequency of the sounds it will increase vibration in certain parts of the cochlea, biggest vibration will occur at the coding area for that frequency
Volley principal
if we have extremely high frequency sounds it isnt just coding cells, we need pools of neurons to work in succession, groups of neurons that fire one after the other that code for very high frequency sounds
auditory localization
Two cues:
1) timing of sounds arriving at each ear (if i have a sound coming from the right side, it will arrive at the right ear first and brain will pick up on that– brain can pick up on a difference as small as one hundreth of a second)
2) intensity aka loudness (if a sound is coming from a right side not only will it get processed first it will be louder in that ear)
Gustation aka taste
receptors in taste buds react to soluble chemical substances (dissolved in our saliva) taste buds are being replace constantly (approx. a week in a half)
taste buds–> neural impulse–> thalamus–> insular cortex
distribution of taste buds
certain parts of our tongue are more sensitive to taste, but the whole tongue can pick up on taste, each person has a different distribution of taste buds on their tongue
5 Tastes
sweet, salty, sour, umami, bitter
super taster
super sensitive to certain tastes (picky eaters) 25% less smokers, less sweets etc usually healthier
cultural and social influence on taste
taught to enjopy certain things often within our culture ex worms, fish eyes, blood (if we are exposed at a young age we might enjoy)
perception of taste
multi sensory experience, smell/taste
olfactory cilia
receptors cells for smell
olfactory process
physical stimuli associated without a sense of smell of substances carried through the air dissolved in the mucus nasal cavity, (cilia are replaced about 30-60 days) olfactory cilia–>neural impulse–> olfactory nerve–> olfactory bulb (brain)
skin senses
mechanical, thermal, chemical– energies impinging on the skin
skin sensory receptors
six types Ex pressure, pain, temperature,
touch process
sensory receptors–> the spinal column–> brainstem–> thalamus–> somatosensory cortex (parietal lobe)
pathway for pain signals
delta fiber c fiber, descending pathway
Delta Fiber
associated with myelinated axons, these signals will be very very fast, first thing that will kick in
c Fiber
non-myelinated axons that will be that pain that you feel after initial pain (throbbing)
descending pathway
from the brain, it goes down and connects to the other pathways, modifies or changes the pain happening in other pathways, focusing on something else might lessen feeling of pain
kinesthesis
knowing the position of the various parts of the body, where we are in space– receptors in joints/muscles (where limbs are, if muscles are flexed)
Vestibular
equilibrium and balance
semicircular canals
a lot of balance is connected to visual system (stabilize the image, allow for clear image when shaking head–damaged canal-appear that world is shaking)