Sensation & Perception Flashcards
Absolute threshold
minimum of stimulus energy needed to activate a sensory system (how powerful a stimulus must be for perception)
-AKA Limen (subliminal perception refers to perception of stimuli below a threshold)
Difference threshold
how different two stimuli must be before they are perceived to be different
JND- just noticeable difference
- same as difference threshold, but different units
- if diff threshold is 2 inches, then it is 1 JND
Weber’s law
change in stimulus intensity needed to produce a JND0 divided by stimulus intensity of the standard stimulus is a constant
Fechner’s law
relationship between intensity of sensation and intensity of the stimulus
Signal detection theory
nonsensory factors influence what the subject says she senses (experiences, motives, expectations..)
(response bias)- tendency to respond due to nonsensory factors
Reception
- 1st step in sensory info processing
- each sensory system has receptors that react to physical energy
Transduction
- 2nd step
- translation of physical energy into neural impulses or action potentials
projection areas
brain areas that further analyze sensory input
cornea
clear, dome like window in the front of eyes
-gathers and focuses incoming light
pupil
- hole in the iris
- contracts in bright light
- expands in dim light to let more light in
Iris
- colored part of eye
- controls pupil size and the amount of light entering eye
Lens
- lies behind the iris
- controls curvature of light coming n and focuses near or distant objects on the retina
duplexity / duplicity theory of vision
- the retina contains two kinds of photoreceptors
- light passes through intermediate sensory neurons before reaching photoreceptors
- blind spot where the optic nerve leaves the eye
Cones
- color vision
- fine detail
- bright light
Rods
- reduced illumination
- low sensitivity to detail and not involved with color
Fovea
- middle section of retina with only cones
- most sensitive in daylight
- best visual acuity
Feature detection theory
-certain cells in the cortex are maximally sensitive to certain features of stimuli
-3 types of cells are
simple
complex
hypercomplex
Simple
Complex
Hypercomplex cell functions
simple- orientation
complex- movement
hypercomplex- shape
Brightness vs illumination
brightness- subjective impression of intensity of a light stimulus
illumination- physical, objective measurement of light
Dark adaptation
caused by regeneration of rhodopsin, the photopigment in rods
Lateral inhibition
adjacent retinal cells inhibit one another; sharpens and highlights borders between light and dark areas
Color perception
wavelength of light entering eye
subtractive color mixture
- when you mix pigments
- blue and yellow make green
additive color mixture
mixing lights
-red and green light make yellow light
Trichromatic theory (young-hemholtz)
- -retina has 3 different cones
- one is very sensitive to red, one to blue, and one to green (3 types of color receptors)
- mixing these 3 primary lights can produce any color
Opponent process theory of color vision (Ewald Hering)
- adds yellow as a primary color
- red blue green and yellow are opposing pairs
- also included black and white
- 3 opposing pairs are red-green, blue-yellow, black-white
interposition (overlap)
if one object covers another, the partially hidden object is seen as farther away
Relative size
comparison of retinal size of object to actual size of objects give cue about depth
Linear perspective
parallel lines appear to converge as they recede into distance
Texture gradients
as scene recedes from viewer, the surface texture of the object appears to change
Motion parallax
when observer moves, objects in a stationary environment appear to move relative to distance from observer
Binocular disparity (stereopsis)
each eye sees a slightly different scene; when brain combines the scenes, we get perception of depth
Figure & Ground
figure- integrated visual experience in the center of attention
ground- background
5 laws that explain perception Proximity Similarity Good continuation Closure Pragnanz
Proximity- elements close together tend to be perceived as a unit
Similarity- elements similar tend to be grouped together
Good continuation- elements that follow same direction tend to be grouped together
Closure- tendency to see incomplete figures as complete
Pragnanz- perceptual organization will always be as good as possible (simple, symmetrical…)
Bottom-up processing (data driven)
responds directly to components of incoming stimulus on the basis of fixed rules and sums up to arrive at a whole pattern
Top down processing (conceptually driven)
guided by conceptual processes like memories and expectations that allow brain to recognize whole objects and THEN the components
apparent motion
when 2+ stationary lights flicker in succession, they are perceived as a single moving light
induced motion
stationary point of light appears to move when the background moves
autokinetic effect
stationary light in a dark room appears to move; caused by involuntary eye movements ?
motion aftereffect
if a moving object stops, it will appear to move in the opposite direction
Preferential looking
2 stimuli are presented side by side. if an infant looks at one longer, they can perceive the difference
habituation
if a new stimulus is presented, and an infant stops looking at the old one, then they can perceive the difference
visual cliff
apparatus designed by gibson and walk to assess infant depth perception
Frequency & intensity
frequency- number of cycles per second in Hertzes
Intensity- amplitude of sound wave in decibels
Pitch
Loudness
& Timbre
Pitch- subjective experience of sound frequency
Loudness- subjective experience of sound intensity
Timbre- quality of sound
Hemholtz’s place-resonance theory
each different pitch causes a different place on the basilar membrane to vibrate which causes different hair cells to bend
Frequency theory
basilar membrane vibrates as a whole (rate of vibration = frequency of stimulus)
touch - two-point threshold
minimum distance necessary between 2 points of stimulation on skin so the points will be felt as 2 stimuli
Physiological zero
a neutral temperature perceived to be neither hot nor cold
gate theory of pain
theory that there is a gating mechanism in the spinal cord that turns pain signals on and off
dichotic listening
different messages in both ears
Yerke’s dodson law
performance is worst at extremely low or high levels of arousal and optimal at some intermediate level
Pinna
channels sound waves into the auditory canal
eardrum AKA tympanic membrane
vibrates in phase with incoming sound waves
-fast for high freq, and slow for low freq
Middle ear
-contains 3 bones called OSSICLES
Hammer, Anvil, & stirrup
-transmit vibrations of tympanum to inner ear
oval window
entrance to inner ear
organ of corti
comprised of thousands of hair cells that transduce bending into electrical charges
Hubel & wiesel
feature detection
-discovered certain cells in the visual cortex involved in detecting various features of stimuli
Semicircular canals
- vestibular sense
- balance and head position
Dots placed closely together so they look like they form rectangles demonstrate the law of
proximity
Two points are placed so close together they are perceived as one. This is because they haven’t reached the
two point threshold
Who quantified weber’s statement of relationship between stimulus and sensation?
Fechner
a stationary point of light when viewed in a dark room appears to move- this is the
autokinetic effect
According to hemholtz and young, the neural basis for pitch perception is
the locationon the basilar membrane that vibrates
What best summarizes current views on feature detectors in the auditory and visual systems?
feature detectors have been clearly demonstrated in both modalities
the analyst must serve as an object onto which hostile impulses are projected is most consistent with the work of
DW Winnicott
which is a physical property of sound? Loudness Frequency Pitch Timbre Hue
Frequency
The ames room experiment demonstrates
the influence of apparent distance on the perception of size
Under dim light a researcher repeatedly displays several objects to a subject so that each time the image falls on a different area of the subjects retina. What is the expected result?
Object discrimination will be worst in the fovea
Ablation of the lateral geniculate nucleus would most like affect which sensory system?
vision
the volley principle can be considered an improvement on
frequency theory
A researcher wants to study the effect of response bias and sensitivity on perception of changes in frequency. She would most like use with theory
signal detection theory
A subject wears a set of headphones that give different messages to each eat. The subject repeats one of the messages as she hears it. This technique is called
shadowing
Which of the following concepts is most relevant to signal detection theory?
ROC curve
Damage to the left visual cortex will
impair vision for images of objects falling on the left half of each eye’s retina
Principal function of the parietal lobe is
spatial processing
