Chapter 5 Flashcards
What are sensations?
stimulus-detection process by which our sense organs respond to and translate stimuli from the environment into nerve impulses sent to the brain
What is perception?
active process of organizing stimulus input and giving it meaning
What is transduction?
nervous system converts external stimulus (e.g. light, sound, touch) into electrical signals
eye –> light
ear –> sound
skin –> pressure, pain, temperature
What are sense receptors?
specialized cell transduces specific stimulus with a sense organ
What is synesthesia?
“mixing of the senses”
cross-wiring of the senses within the brain
fMRI and DTI support this condition (you’ll see activity increased in those sensory areas that correspond to the cross wired senses
What is psychophysics?
studies the relationship between physical characteristics of the stimuli and our perception of those stimuli
measured two ways: limits of detection (absolute threshold), minimum needed to detect a change (JND)
What is absolute threshold?
lowest intensity in which a stimulus can be detected 50% of the time
sometimes it will be perceived, sometimes not
lower threshold, greater sensitivity
What is signal detection theory?
absolute threshold is not fixed
ask patients to indicate if they perceived a stimulus, 2 conditions: stimulus present, stimulus absent
leads to four outcomes and individual variability in decision criterion
What is decision criterion?
standard of how certain we are of a stimulus in order to say we detected it
What would a performance profile look like for someone who is conservative?
need a lot more to say they heard the tone
get more misses and less false alarms
What would a performance profile look like for someone who is liberal?
say yes a lot
get less misses, and more false alarms
What is a difference threshold?
the smallest difference between two stimuli that can be detected 50% of the time
aka Just Noticeable Difference
stronger stimuli need a bigger change before noticing, notice two candles are brighter than one candle, won’t notice 101 candles are brighter than 100
What is Weber’s Law?
constant proportional relationship between the JND and stimulus magnitude
What is sensory adaption?
sensory neurons are finely attuned to changes in stimulation
activation declines over time, leading to sensory adaption
conserves energy and attentional resources
What is the lens?
the lens will accommodate by getting thicker or thinner so that we can see objects closer or further away
What is the retina?
location of visual transduction
fovea: the most cones, no rods, clearest vision
blind spot: no rods or cones
What are photoreceptors (rods)?
black/white
functions best in low illumination
mostly in periphery
everywhere but fovea
What are photoreceptors (cones)?
color and detail
functions best in high illumination
near center of retina
fovea only contains cones
What is dark adaption?
have “dual visual system”
rely on rods for vision in low light conditions
rods and cones adapt differently
cones adapt after ten minutes
rods adapt after thirty minutes
What is trichromatic theory (Young-Helmholtz)?
three types of color receptors in retina
cones most sensitive to blue, green, red wavelengths
visual system combines activity from these cells
colors are perceived by additive mixture of impulses
if all are equally activated, white color is produced
What is the opponent process theory (Hering, 1870)?
three cone types
each responds to two different wavelengths, (red or green, blue or yellow, black or white)
can explain some visual phenomenon that the trichromatic theory cannot (afterimages, contrasting colors)
What are the limitations of trichromatic theory?
color blind individuals (red-green color blind individuals should not be able to perceive yellow, but they can)
afterimages (stare at red, look away you’ll see green)
What is colorblindness?
absent or reduced number of one (or more) cone types
monochromats: no color vision (rare)
dichromats: 2 cone types
more common in males (X-linked genes)
What is the concept of visual scenes?
different brain areas process different aspects of vision
What is frequency?
number of sound waves (cycles) per second
unit of measure = Hz
higher frequencies = higher pitch
What is amplitude?
vertical size of the sound waves
unit of measure: decibels (db)
higher amplitude = louder
amplitude: physical pressure on eardrum, loudness: perception of loudness
logarithmic scale (10 db increase = 10x loudness)
What are the sections of the ear?
outer ear: pinna and ear canal, eardrum
middle ear: ossicles (malleus, incus, staples), oval window
inner ear: cochlea, basilar membrane
What is the cochlea?
location of transduction: sound waves into electrical impulses
outer part is bony
filled with fluid that is distributed by sound waves
organ of corti and the basilar membrane: hair cells bend, releasing NT, auditory nerve receives signals, sends to brain
What are the theories of pitch perception?
Place theory
Frequency theory
What is Place Theory?
location within cochlea where signal is transduced correlates to the pitch
tonal frequency “map”
best for high pitch (5,000 to 20,000 Hz)
What is Frequency Theory?
nerve impulses sent to the brain match the frequency of the sound waves
best for low pitch (below 1000 Hz)
What is sound localization?
monaural cues: one ear, are sounds coming right in front, above, or below
binaural cues: interaural intensity difference, interaural time difference
What is interaural intensity difference (IID)?
left ear, intensity is less, calculate and compare intensities
What is interaural time difference (ITD)?
calculate how quickly sound got to one ear compared to another
What are the different types of deafness?
conduction deafness: mechanical problems, punctured eardrum, calcification of ossicles, hearing aid
nerve deafness: damage to hair cells or auditory nerve
noise-induced hearing loss
aging
What is Gustation (taste)?
5 basic receptors: sweet, sour, salty, bitter, umani
other qualities combine to affect taste, such as smell, temperature, and touch
adaptive significance: seek out nutrients, avoid toxins
What are taste buds?
substance and saliva combine to make solutions which flow into papillae to stimulate receptors
paillae hold taste buds, in which there are different types
different taste cells in each taste bud
cells are replaced roughly every ten days
What are odours?
less is known about how we discriminate odors
current theory: receptors recognize diverse odors individually, rather than mixing activity
airborne molecules bind to olfactory bulb
What are pheromones?
odorless chemicals for intraspecies communication
unsure whether humans secrete pheromones
What are tactile senses?
somatosensory system
touch, pressure, pain, warmth, cold, kinesthesis, equilibrium
What is pain?
receptors respond to mechanical, thermal, or chemical stimulation
send message to: spinal cord –> thalamus –> somatosensory + frontal areas or limbic system
pain processed faster than touch
What is gate control theory?
the experience of pain results from opening/closing gating mechanisms in spinal cord
both physical and psychological
rub/poke an injury will make it hurt more
thoughts, emotions, and beliefs can modulate pain
What are endorphins?
built in pain killers in nervous system
inhibits release of NT involved in synaptic transmission of pain
What is kinesthesis?
feedback about joint/muscle position
receptors: nerve endings in muscles, joints, tendons
What is equilibrium in the vestibular sense?
body orientation
receptors in inner ear (semi-circular canals)
What is bottom-up processing?
- Perception of individual stimulus elements
- Breakdown or analysis of stimuli
- Combination and interpretation of “whole”
What is top-down processing?
- Concept, expectation
- Guides analysis
- Interpretation of incoming stimuli
What is the role of attention?
attention helps to: focus on certain stimuli and filter out other incoming information
shadowing techniques: cannot completely attend to more than one thing
inattentional blindness: if we don’t attend to something, we don’t “see” it
What are Gestalt Principles?
our perception is often more than the sum of its parts
Gestalt Laws: similarity, proximity, closure, continuity
What is perception?
testing hypotheses and influenced by expectation
What is perceptual schema?
ability to “recognize” something suggests we have a mental representation with which to compare
What is perceptual set?
a readiness to perceive stimuli in a certain way
What are perceptual consistencies?
allows us to recognize familiar stimuli under varying conditions
recognize a tune even if played in a different octave
shape, brightness and size consistency
What is depth perception?
Retina only receives 2D information, but we see in 3D
two ways: monocular and binocular cues
What is binocular disparity?
each eye sees a slightly different image
the differences are analyzed by feature detectors tuned for depth
convergence: feedback from eye muscles when looking at a close object
What is movement perception?
brain integrates information from different senses
phi phenomenon (stroboscopic movement): see movement when it’s not there, allows us to watch movies
What is the relationship between experience and perception?
experience gained over development leads to changes in perception
