Chapter 4 Flashcards
sensation
detection of physical energy by our sense organs
perception
the brain’s perception of the raw sensory inputs
transduction
the process where the nervous system turns external stimuli into electrical signals within neurons via sense receptors ex. mechanical receptors, rods and cones, olfactory cilia, ect.
what is sensory adaptation and what is its adaptive purpose
gradual decline in sensitivity due to prolonged stimulation, adaptive process - keeps us in tune to the changes in our environments rather than its constants
what is psychophysics, who founded it, and what was its significant finding?
The study of how we perceive sensory stimuli based on their physical characteristics, founded by Gustav Fechner, first to describe that a stimulus is required for sensation
absolute threshold
the lowest level of a stimulus that we can detect (at least 50% of the time). Stimulus much reach absolute threshold in order to be detected
ex. a candle flame 50 km away on a dark and clear night
“something compared to nothing”
just noticeable difference (JND)/difference threshold
The smallest change in the intensity of a stimulus that we cant detect(at least 50% of the time)
ex. detecting the difference between the brightness of 2 different flashlights from a distance
Weber’s Law
there is a constant and proportional relationship between the JND and the original stimuli
ex. the difference between a 10lbs weight and an 11lbs weight is 10% so you can feel it. but if you have a 100 lbs weight and a 101 lbs weight, proportionally you won’t feel the difference because its no longer 10%.
Weber’s fraction
the constant proportion mentioned in Weber’s Law
Synesthesia
condition where people experience cross-modal sensations and perceptions, most common type is grapheme-colour synesthesia(where a persons experience of numbers and letters are associated with colour)
what is selective attention, what systems are involved and how is it studied?
ability to attend to one thing and exclude all else/ select one sensory channel and ignore or minimize others,
Reticular Activating System and forebrain involved
studied using dichotic listening tasks
Inattentional blindness
when we pay attention to some events in a scene, we may fail to notice when an unexpected but completely visible object suddenly appears
how do attention and perception interact
selective attention, inattentional blindness
Broadbent’s filter model
the only thing you understand is the the meaning of the words the person you are paying attention to is saying and filter everything else out
doesn’t explain cocktail effect (our ability to pick out important word like our name, s in conversations that do not involve us)
The binding problem
different aspects of complex stimulus are processed in different parts of the brain, but we perceive the stimulus as a single unit. psychologists can’t explain how the rapid binding of these sitmuli works.
Name and describe the 2 parallel processes of perception
Bottom-up processing: we construct a whole stimulus from its parts, starts with activity in the primary visual cortex, then processing in the association cortex (stimulus driven)
Top-down processing: influences what we perceive due to our beliefs, expectations, and past experiences, starts with processing in the association cortex, then processing in the primary visual cortex.(conceptually drive)
happen simultaneously
perceptual hypothesis
educated guesses about what our sensory system is telling us. Mostly correct, but not always.
perceptual sets
and example of top-down processing, when our expectations influence our perceptions in a specific way in a given circumstance or environment
what is perceptual constancy, and what are the 3 types
the process by which we perceive stimuli consistently across varied conditions
size constancy
shape constancy
colour constancy
Gestalt Principles of perception
rules governing the way we perceive an object as a within their overall context
proximity
similarity
continuity
closure
symmetry
figure-ground
proximity
close objects are perceived as a whole
similarity
similar objects appear as a whole
continuity
we perceive objects as wholes even if another objects block a part of them (+ is perceived as 2 whole lines)
closure
the tendency to fill in gaps
symmetry
the tendency to see things in the most symmetrical/simplest way possible
figure-ground
we only focus on what we believe to be the central figure of an image and ignore the background ex. bistable image
perceiving motion
we determine whether something is moving by comparing visual frames from one moment to the next, visual receptors that activate from one millisecond to the next have tiny differences that our brain perceives as motion
Phi phenomenon
apparent motion, when stimuli flash in different locations next to each other giving the illusion of movement
Face perception
we may be born with the ability to recognise some objects, like faces
perceiving depth and the 2 types of depth cues
ability to see spatial relations in 3D
Monocular depth cues
binocular depth cues
Light
form of electromagnetic radiation that travels as a wave, vary in amplitude, wavelength, and purity
amplitude
affects perception of brightness
subliminal perception
registration of sensory input without conscious awareness
wavelength
affects perception of colour (hue)
purity
affects perception of saturation/richness of the colour
rods
nighttime vision, peripheral vision
ciliary muscles
contracts or stretches lens, when you focus on a close object the lens roundens, when you focus on a distant object the lens flattens
near point
the point where your eyes can no longer adjust your lens so the light focuses onto the retina (too close)
The eye
reflected light enters the pupil, cornea and lens focuses the light on the retina where photo-receptors (rods and cones) are stimulated, then stimulating bipolar neurons, which stimulate ganglion neurons, which form the optic nerve
presbyopia
the distance of the near point for focusing the eye changes as we age, the old eye
Monocular depth cues
relays on 1 eye
2 kinds:
motion parallax: ability to judge distance of an object based on its speed; farther=slower, closer=faster
pictorial depth cues: clues about distance that can be given in a flat picture (linear perspective, texture gradients, interposition, relative size, height in plane, light and shadow)
The cornea
clear layer that covers the eye and lets light in, focuses it to the fovea centralis
Binocular depth cues
relays on both eyes
1. binocular disparity: each eye sees the world differently, allowing us to judge depth
2. binocular convergence: when looking at close objects our eye muscles turn our eyes inwards(convergence). Our brains estimate distance based on how much our eyes are converging.
The lens
flexible and adjusts to focus the light from near or far objects
the retina
neural tissue that absorbs light, processes images and sends visual information to the brain, contains rods and cones
fovea centralis
focal point, responsible for acuity, high concentration of cones
cones
daylight vision colour vision
trichromatic theory
colour vision depends on activity of 3 different colour receptor types (red, green, blue)
opponent-process theory
colour vision is related to opposing responses by blue and yellow, black and white, and red and green
dual-process theory
incorporates both trichromatic and opponent-process theory to explain colour vision
sound waves
mechanical energy, vibrating molecules
pitch
frequency of sound waves, measured in hertz (Hz)
amplitude
loudness/height of sound waves, measured in decibels (dB)
complexity/timbre
quality/complexity of the sound
conductive deafness
when you have damage to an ear structure (outer or middle ear)
nerve deafness
damage to the auditory nerve
taste preferences
some are innate, most are learned
gustatory cortex
specialized area of the brain that processes taste, found underneath motor cortex
variations in taste
non-taster, super-taster, medium taster
flavour
the combination of taste and smell
somatosensory system
system responsible for body sensation of touch, temperature and pain
nocioception
perception of pain and temperature
hapsis
perception of objects using touch and pressure
vestibular sense
sense of equilibrium/balance
nocioceptive pain
pain caused by the activation in the free nerve endings in the skin (heat, chemical, pressure, cold), pain information goes to the somatosensory cortex of the frontal lobe and the limbic centers in the brainstem/forebrain
inflammatory pain
pain caused by damage to tissues and inflammation of joints
neuropathic pain
pain caused by lesions or damage to the nervous system
pain perception
activation of somatic nerves synapse with spinal cord, touch signals travel faster than pain, activate spinal reflex, travels to the somatosensory cortex
pain perception pathways
fast pathway (A-delta pathway)-accute pain sensation
slow pathway (C fibre pathway)-long term pain ex. headache
proprioception/ kinesthetic sense
muscle position sense; lets us know where our body parts are relative to ourselves, move efficiently
proprioceptors
sense muscle stretch and force, 2 types: stretch and force
what are the 2 types of proprioceptors
stretch receptors are embedded in muscles, and force detectors are embedded in tendons
prosopagnosia
face blindness
fusiform gyrus
region of the temporal lobe that plays an important role in facial recognition, damage can result in prosopagnosia
blindness
the presence of vision equal to or less than 20/200 on the Snellen eye chart. Causes: cataracts (clouding of the lens), glaucoma (pressure on the eye that damages the optic nerve), retinal cancer, stroke
cortically blind
when the brain fails to register visual sensory input (usually due to stroke)
visual agnosia
deficit in perceiving objects- can tell shape/colour of an onject, but can’t name it
Cells of the Visual Cortex
simple and complex, they detect slits of light at specific oreintations (vertical, horizontal, oblique, or edges) complex cell responses are less restricted to one area
feature detection
our ability to use certain minimal patterns to identify objects
visual cortexes
Primary (V1), Secondary (V2), Tertiary (V3)
hue
the colour of light
additive colour mixing
red+green+blue= white
subtractive colour mixing
yellow=cyan=magenta= black
accommodation
lens changing shape
lens flattening
focusing on distant objects
lens round
focusing on nearby objects
nearsightedness/myopia
eye too long or cornea too round, image focuses in front of the retina, can’t see far
farsightedness/hyperopia
eye too short or cornea too flat, image refracts behind fovea, can’t see close
dark adaptation
the time it takes rods to regain their maximum sensitivity to light
photopigment
chemicals that change following light exposure, in rods the photopigment is rhodopsin
optic chaism
where the optic nerves cross, half the neurons go to one eye, half go to the other, allows for depth perception
blind spot
where optic nerve connects to retina, no rods or cones
How does transduction occur in the ear?
The basilar membrane contains the organ of corti which has cilia that extend into the fluid of the cochlea. When sound waves travel through the fluid, the pressure excites the cilia, that feed the info to the auditory nerve, then the thalamus, then the brain stem, then the auditory cortex of the temporal lobe
pitch perception/place theory
hair cells located rat the base of the basilar membrane are excited by high pitch tones, while the hair cells at the top of the basilar membrane are excited by low pitch noise
frequency theory
the rate at which neurons fire action potentials reproduces pitch, works well up to 100 Hz
volley theory
sets of neurons fire at their highest rate (100 Hz) slightly out of sync to reach rates of 5000 Hz
noise-induced hearing loss
damage to cilia from prolonged exposure to loud sounds
smell/taste
olfaction/gustation
odours
airborne chemicals
path of odour
odour - sensory receptor - limbic system/oflactory cortex (frontal lobe)
path of flavour
food partical- taste bud - brain stem - thalamus - gustatory/somatosensory cortexex (frontal lobe)
orbitofrontal cortex
where smell/taste converge
Gate control model of Ronald Melzack
Pain under extraordinary circumstances is blocked from consciousness because of neural mechanisms (small nerve and large nerve fibres) in the spinal cord that function as a “gate”, controlling flow of sensory input to brain (stimulation blocks pain from conciousness)
Small nerve fibres
Sense pain, open gate to send pain signals to the brain
Large nerve fibres
Respond to normal sensations of touch/pressure, can inhibit small nerve fibres, therefore blocking pain signals from the brain
subjective contours
when our brains provide missing information about outlines (essentially the gestalt principle of closure)
parallel processing
our ability to attend to many different sensations
Binaural cue
when the auditory nerve enters the brain stem, half the axons connect to cells on the same side of the brain, the other half cross to the other side. Because the auditory info takes different routes, the arrive at the brain stem slightly out of sync, allowing us to localize sounds
Monaural cues
cues heard by one ear only that distinguish clear sounds from ones that are muffled by the head(sound shadow) allowing us to figure out where sounds are coming from
subliminal persuasion
changes in behaviour due to subliminal perception
phermone
odourless chemical that serves as a social signal to members of ones’ species
