Chapter 5 - Sensation and Perception Flashcards
what is the difference between perception and sensation?
info comes through our senses
out brain interpret this information
what is a sensation?
stimulus-detection process
organs translate stimuli into nerve impulses
what is perception?
organizing and giving meaning to input
depends on cortex assigning meaning to is
very active process
can the same stimulus be perceived differently in different context?
yes
what is the process of a stimulus to perception?
stimulus -> sensory receptors -> Transduction -> neural impulse -> perception
what is psychophysics?
studies relations between physical characteristics of stimuli and sensory capabilities
what are the 2 kinds of sensitivity?
absolute threshold
difference threshold
what is absolute threshold?
askes about the absolute limit of sensitivity
eg. how bright does a light have to be before we can see it?
what is the difference threshold?
askes about the difference between stimuli
eg. what is the smallest difference in brightness that er can detect?
lower absolute threshold = greater sensitivity
what is Weber’s law?
JND is proportional to the magnitude of the stimulus with which the comprison is being made
what is sensory adaptation?
diminishing sensitivity to unchanging stimulus
occurs in all sensory modalities
adaptive value
- frees senses from the unchanging to be
more sensitive to changes in the
environment
what are the 2 types of processing to turn sensory info into perceptual?
bottom-up processing
top-down processing
what is bottom-up processing?
taking sensory info and then assembling and integrating it
what is top-down processing?
using models, ideas and expectations to interpret sensory information
what is an example of to-down influences?
perceptual set
what is a perceptual set?
when we see what we expect to see
what is the 2 processes that are involved in attention?
focusing on certain stimuli
filtering out other information
what three ways does attention determine what we see?
divided attention
selective attention
inattentional blindness
what is divided attention?
multitasking or paying attention to more than one stimulus or task at a time
what is selective attention?
involves focusing on one stimulus or task while ignoring other stimulus
can miss thing in a scene if focusing on one thing
how do you study selective attention?
studied using the dichotic listening task
results suggest that much of the unattended channel foes unnoticed
some exceptions: cocktail party (hearing your name in a loud room)
what is inattentional blindness?
when the effect of attention are so strong that we fail to see stimuli that are directly in front of our eyes
what is the Gestalt principles of perceptual organization?
argued that the wholes we perceive are more than the sum of their parts
suggests perceptions was governed by laws that determine how things were grouped together
what is figure-ground?
most fundamental gestalt principal
simplest form of organization, pick out objects and figures standing against a background
can be ambiguous
idea behind camouflage
what are the 4 gestalt principals?
proximity
similarity
continuity
closure
what is proximity?
elements that are close together belong together
what is similarity?
similar items belong together
what is continuity?
elements liked to form continuous line
what is closure?
close open edges; perceive boundaries
what is perceptual constancies?
refers to our ability to see objects as appearing a constant colour, size and shape despite continual changes in out perception (top-down process)
what is colour constancy?
we see a consistent colour in changing illumination conditions
what is brightness constancy?
we see consistent brightness in changing shadow conditions
what is shape consistency?
we see a consistent shape in an object despite receiving different sensory images of the shape
what is depth perception?
image on the retina is 2D, but we live in a 3D world
how do we perceive depth from a 2D image?
monocular cues
binocular cues
what is a monocular cue?
depth can be perceived with one eye
what is binocular cues?
depth perceived with 2 eyes
what are the 7 monocular cues?
accommodation, relative motion, interposition, relative size, linear perspective, and light and shadow
what is accommodation?
we can detect changes in the shape of our lens as a cue to distance
what is relative motion?
when we are moving, we can see how far away we are from something from how fast or slow it takes to pass it
what is interposition?
when one object appears to block the view of another, we assume the blocked object is farther
what is relative size?
we assume familiar objects as farther away when they appear smaller
what is linear perspective?
we see parallel lines as converging in the distance
what is the Ponzo illusion
our perception of distance affects our perception of length
what is light and shadow?
shadows can give clues to the location and size of objects
what is binocular depth cues based on?
retinal disparity
convergence
what is renal disparity?
two eyes receive different visual images
feature detectors analyze differences
what is convergence?
feedback from ocular muscles when focusing on something distant and then close
what stimulus does the visual processes?
light or waves of electromagnetic radiation around 360-750mn
what is wavelength/ frequency of light perceived as?
colour
what is amplitude of a light wave perceived as?
brightness
what does light travel through?
the cornea -> pupil -> focused at the lens
where does the light land on?
the retina to get transduced into a neural signal
what is the first layer of the retina?
photoreceptors
- transduces light waves into
neural impulses
- rods and cones
what are rods?
functions best in low illumination
sound mostly periphery of retina and on in fove
what are cones?
for colour and detail
functions best in high illumination
concentrated in fova (center of retina)
what is dark adaptation?
progressive improvement in brightness sensitivity in low illumination
rods adapt after 30 minutes
cones adapt after 10 minutes
what is layer 2 of the retina?
bipolar cells
what are bipolar cells?
rods and cones have synaptic connections with bipolar cells
cones have one to one connections well many rods connect to one bipolar cell
what is layer three in the retina?
ganglion cells
what are ganglion cells?
bipolar cells synapse with ganglion cells
axons of ganglion cell form the ocular nerve
what is the optic disc?
an area of the retina that contains no rods or cones because this is were the optic nerve leaves the eye
causes blind spots in your vision
what is the trichromatic theory (Young-Helmholtz)?
three types of colour receptors in retina
visual systems combines activity from these sells to allow us to perceive all the colours
what is the problem with the trichromatic theory?
can’t explain why red-green colour blind individuals can perceive yellow
can’t explain afterimages
what is the opponent theory?
three cone types and each respond to 2 different wavelengths
red or green
blue or yellow
black or white
explains afterimages
where do impulses from the ocular nerve go?
thalamus to the primary visual cortex (occipital lobe)
fovea has large representation in visual cortex
what are feature detectors?
cells in primary visual cortex that are very particular about what will make then fire
what are the two pathways of feature detectors?
the visual stream
the dorsal stream
what is the stimulus for the auditory system?
sound waves
what are the two characteristics of sound waves?
frequency (pitch) and amplitude (loudness)
what are the 2 types of hearing loss?
conduction hearing loss
sensorineural hearing loss
what is conduction hearing loss?
when the middle ear isn’t conducting sound well to the cochlea
what is sensorineural hearing loss?
when the receptor cells aren’t sending messages through the auditory nerves
how do you prevent hearing loss?
exposure to sounds that are too loud to talk over can cause damage to the hair cells
structures in the middle of the ear can be damaged by disease
how do you treat hearing loss?
conductions hearing loss helped with hearing aids that amplify the sound
sensorineural hearing loss helped with cochlear implant that translates sound waves into signals for the brain
what is loudness?
refers to more intense sound vibrations that the brain can interpret using :
- firing rate of hair cells
- number of hair cells firing
- the type of hair cell firing
what is the frequency theory?
nerve impulses match frequency of wave
doesn’t work for frequencies above 1000Hz
what is place theory?
specific frequencies peak at certain places on the cochlea, depending on pitch
the brain reads pitch by reading the location where the signals are coming from
what 2 ways does binaural hearing help localize sounds?
timing of sound
intensity of sounds
where do sound impulses go?
thalamus to the primary auditory cortex (temporal lobe)
from there, signals go to the secondary auditory cortex (interoperates complex sounds)
