chapter 3 Flashcards
sensation
senses detect visual, auditory, and other sensory stimuli
transmits stimuli to brain
perception
sensory information is actively organized and interpreted by brain
absolute threshold
difference between not being able to perceive it and being able to perceive it
minimum amount of sensory stimulation detected 50% of the time
hearing music means the threshold has been crossed
difference threshold
measure of smallest increase/decrease in physical stimulus required to produce JND
JND (just noticeable difference) smallest change in sensation detected 50% of the time
Weber’s law
Ernst Weber came up with this 150 years ago
States JND depends on percentage change in stimulus
Greater original stimulus more increase needed for JND
Signal detection theory
noticing stimulus against background noise and deciding if stimulus is really there
sensory receptors
detect, respond to one type of stimuli
Transduction
sensory receptors change sensory stimulation into neural impulses
Sensory adaption
become less sensitive to unchanging sensory stimulus over time
photons
tiny light particles that travel in waves
majority of these waves too long/short for animals/humans to see
our eyes respond to visible spectrum
Cornea
tough, transparent, protective layer covering front of eye, bends light rays inwards through pupil.
pupil
small dark opening in middle of eye
Iris
coloured part of eye
muscles dilate and contract pupil through reflex
Lens
lots of thin layers and it is clear disc
flattens while focusing on distant objects
bulges in centre while focusing on close objects
accommodation
flattening and bulging motion
Lens to retina
lens focuses images onto retina a thin membrane
contains sensory receptors for vision
image projected onto retina is upside down and reversed left to right
Nearsightedness (myopia)
distance through eyeball are too short or too long
see nearby objects clearly distant images blurry
Farsightedness (hyperopia)
focal image longer than eye can handle
acts as if image should focus behind retina
see distant objects clearly close objects blurry
Rods
light sensitive receptors in retina
responds to white and black
encode in shades of grey
cones
receptor cells in retina
help see colour and fine detail
don’t function in very dim light
Fovea
retina to brain
small area of retina clearest point of vision
largest concentration of cones
change light rays into neural impulses
impulses transmitted to bipolar, amacrine, horizontal cells, then ganglion cells
ganglion cells bundle into cable leaving retinal wall on way to brain
blind spot
where cable runs through retinal wall
optic nerve
after cable leaves retinal wall
optic chiasm
optic nerves from both eyes come together, nerve fibres cross to opposite sides of brain
helps depth perception
feature detectors
certain neurons in brain
only responds to specific visual patterns lines or angles
coded at birth to make unique responses
hue
colour we see (red,blue,green)
saturation
purity of colour
brightness
intensity of light energy we perceive
Trichromatic theory
3 types of cones in retina
each type makes it maximum chemical responses to blue red green
theory consistent with what happens with cones
opponent-process theory
3 classes of cells
red/green yellow/blue black/white
increase/decrease firing rate when different colours are present
negative afterimage
use opponent process pairs
stare at one colour brain will give sensation of opposite colour on white surface
colour processing
starts at level of retina
continues through bipolar and ganglion cells
completed in colour detectors in visual cortex
colour blindness
inability to distinguish certain colours
8% males 1% females’
males main issue diff between red and green
genes for colour vision are carried in x chromosome
frequency
hertz
number of cycles completed by sound wave in one second
amplitude
(Db) loudness of sound caused by force or pressure with which air molecules move
Timbre
distinct quality of sound distinguishing it from other sounds of same pitch and loudness
Pinna
outerear
visible curved flap of cartilage and skin
auditory canal
2.5 cm long lined with hairs
leads to eardrum
eardrum
tympanic membrane
thin flexible membrane
about 1 cm in diametre
moves in response to sound waves
Ossicles
middle ear
3 smallest bones in body
amplify sound 22 times
hammer, anvil, stirrup, link eardrum to oval window
Cochlea
inner ear
fluid filled, snail shaped bony chamber
stirrups push against oval window vibrations move cochlear fluid in waves
waves move basilar membrane cell hair
produce electrical impulse transmitted to brain
Place theory
we hear individual pitches
cant explain how we can perceive frequencies below 150 hertz
frequency theory
500 hz tone stimulates hair cells to vibrate 500 times per second
not valid for high frequencies
cannot fire more than 1000 times per second
conductive hearing loss
soundwaves cannot be conducted to cochlea
hearing aid can by pass middle ear
uses bone conduction to reach cochlea
sensorineural hearing loss
damage to cochlea or auditory nerve
hearing aids can help if damage to cochlea is too severe
hearing aids no help if damage to auditory nerve
olfaction
sensation of smell a chemical sense
olfactory epithelium
patch at tissue at top of each nasal cavity
contains 10 million smell receptor cells
olfactory bulbs
2 matchstick sized structures above nasal cavities
smell sensations first register in brain
messages from this relayed to different parts of brain
pheromones
chemicals excreted by animals/humans
elicits certain behaviour patterns
Gustation
sense of taste
4 basic tastes bitter, sweet, salty, sour
umamii 5 th taste response to glutamate found in protein rich foods like cheese, meat
flavour
sensory experience of taste, smell, touch,
much of taste is smell
brain perceives 2 distinctive flavours present in sweet and sour very differently
taste buds
small bumps called papillae 4 types of papillae 3 types of papillae have taste buds each taste bud has 60 to 100 receptor cells continually replaced
non tasters
reduced ability to taste smallest number of taste buds per square cm
(96)
medium tasters
nearly twice as many taste buds (184)
supertasters
more than 4x as many taste buds (425)
mechanism of touch
nerve endings send touch message through nerve connections to spinal cord
Gate control theory
pain signals can be transmitted or inhibited by “gate” in spinal cord
Endorphins
block pain and produce feelings of well-being
acupuncture
relieves stress by stimulating release of endorphins
kinesthetic sense
feedback about movement and position of various body parts
vestibular sense
detects movement
provides info about body’s orientation in space
semicircular canals
senses rotation of head when turning head side to side
signals changes in motion or orientation
Gestallt
german word that means form pattern a figure we see
figure ground principle
principle of perceptual organization
visual field perceived in terms of object against background
perceptual constancy
view people from different angles, distances, lighting conditions
size constancy
see same size regardless of changes in retinal image
shape constancy
see stable or unchanging shape regardless of differences in viewing angle
brightness constancy
see same brightness regardless of differences in lightning conditions
colour constancy
see same colour under different conditions of illumination
convergence
BINOCULAR
eyes turn inward while focusing nearby objects
closer object greater convergence
binocular disparity AKA retinal disparity
binocular
difference between 2 retinal images
cues for depth and balance
binocular depth cues
cues from both eyes
monocular depth cues
cues from one eye
interposition
monocular
perceive partially blocked object as farther away
linear perspective
parallel lines appear to converge into distance
relative size
larger objects perceived as closer to viewer, smaller objects as farther away
texture gradient
monocular depth cue
nearby objects appear to have sharply defined textures
similar objects appear smoother
appear fuzzier the farther away
Atmospheric perspective
monocular depth cue
distant objects have blue tint
distant objects blurrier than close objects
Shadow/shading
monocular depth cue
distinguish bulges from indentations by shadows
motion parallax
monocular depth cue
look out side of window
objects appear to be moving in opposite direction
objects seem to be moving at different speeds
real motion
movements of objects through space
apparent motion
psychological
autokinetic illusion
stare at single unmoving light in dark room appears to move
phi phenomenon
(strobescopic) neon lights flashing looks like movement
ambiguous figures
2 different objects
figures seen alternately
impossible figures
parts appear to be 2 different places at same time
illusions
false perception or misperception of actual stimulus in environment
bottom up processing
information transmitted to areas of brain then combined ,assembled into whole pattern person perceives
ex. deciphering doctors writing
top down processing
past experience, knowledge of context plays role in forming perceptions
we perceive more than sum of individual elements taken in by sensory
ex. pharmacist can decipher your doctors prescription and fill it
perceptual set
expectations affect perceptions
attention
process of sorting sensations and selecting some into further processing
inattentional blindness = failure to notice changes in objects if not directly paying attention
