Chapter 2-sensation & perception Flashcards
sensation
transduction, conversion of physical, electromagnetic, auditory, and other info from environment into electrical signals to the CNS
perception
processing of sensory info
difference threshold
minimum difference in magnitude between 2 stimuli that is required to detect the difference
Weber’s law
there is a constant ratio between the change in stimulus magnitude needed to produce a difference threshold and the magnitude of the original stimulus; for larger magnitude stimulus, the actual difference must be larger to perceive that difference
signal detection theory
internal (psychological) and external (environmental) context influences the perception of the same stimuli
Response Bias
tendency to systematically respond to a stimulus a particular way due to nonsensory factors.
signal detection experiment
consists of many trials where stimulus may or may not be presented; catch trials: signal presented; noise trials: signal not presented (think of white noise); after each trial participant asked if signal was presented; 4 outcomes: hits (correctly perceived the signal), miss (fails to perceive signal), false alarms, and correct negatives (correctly identifies that no signal was given
adaption
decrease in stimulus perception over time
retina
back of the eye, converts incoming photons of light into electrical signals
duplexity/duplicity theory of vision
retina contains 2 kinds of photoreceptors, rods and cones
cones
color perception, fine details; come in three different forms for long, medium, short wavelenghs
rods
more functional in reduced illumination, contain rhodopsin, better for night vision and peripheral
fovea
central retina where best visual acuity, contains only cones
visual pathway
photoreceptors-bipolar cells-ganglion cells-optic nerve-hemidecussation-LGN of thalamus-visual cortex
amacrine and horizontal cells
receive input from multiple retinal cells before passing on info to ganglion cells
parallel processing
ability to simultaneously analyze and combine info on color, shape, and motion. Feature detection: have cells that specialize in color, shape, motion
parvocellular cells
ability to see shape and distinguish object from background, color, fine detail, low temperal resolution (only can see stationary or slowly moving objects)
magnocellular
detect motion, high temporal resolution, blurry but moving image of object
vestibular sense
rotational and linear acceleration of the ear
pinna/auricle
outside part of ear, channels sound waves to external auditory canal
external canal
directs sound to tympanic membrane (eardrum)
tympanic membrane
vibrates in phase with incoming sound waves; sound wave frequency determines rate of vibration; louder sounds-greater intensity, greater amplitude; divides outer ear from middle ear
middle ear
contains three small bones: ossicles- transmit and amplify vibrations from ear drum to inner ear; malleus (hammer) attached to tympanic membrane acts on incus (anvil), which acts on stapes (stirrup); middle ear attached to Eustachian tube-helps equalize pressure
inner ear
sits within bony labyrinth which includes cochlea, vestibule, and semicircular canals; structures are filled with membranous labyrinth, bathed in potassium rich fuild called endolymph and perilymph (cushions inner ear structures and transmits vibrations)
Cochlea
contains organ of Corti, the actual hearing apparatus, which sits on basilar membrane; organ composed of lots of hair cells
Hair cells
receive vibrations through perilymph, convert physical stimuli into electrical signals, which are carried by auditory (vestibulocochlear) nerve; long tufts of stereocilia which sway from vibrations-swaying opens ion channels-receptor potential; which hair cells are vibrating tells brain info on pitch
auditory pathway
hair cells-auditory nerve-medial geniculate nucleus-auditory cortex
olfactory chemoreceptors
chemical stimuli binds chemoreceptors in olfactory epithelium in nasal cavity to cause a signal
olfactory pathway
odor molecules inhaled in nasal passages-olfactory nerve-signal to olfactory bulb
two-point threshold
minimum distance necessary between two points of stimulation on skin such that the points will be felt as two separate stimuli
physiological zero
normal temperature of skin; object feels cold when less than physiological zero
nociceptors
pain receptors
gate theory of pain
other touch signals can inhibit perception of pain
kinesthetic sense
proprioception; ability to tell where your body is in space
bottom-up processing
object recognition by parallel processing and feature detection, combine individual sensory stimuli to create cohesive image; happens quickly, body reacts before brain, takes in different sensory stimuli, tells brain what to do
top-town processing
driven by memories and expectations that allow the brain the recognize the whole object and then recognize components, like looking at an object for the first time; perception is driven by brain, which applies what it knows and what it expects to see, when given specific context, brain expects certain stimuli
perceptual organization
ability to use both top-down and bottom-up processes together to form complete picture
Gestalt principles
ways for brain to infer missing parts of an incomplete picture
law of proximity
elements close to each other tend to be perceived as a unit
law of similarity
objects that are similar tend to be grouped together
law of good continuation
elements that appear to follow in the same pathway tend to be grouped together, tendency to perceive continuous patterns in stimuli
law of closure
when a space is enclosed by a contour, it tends to be perceived as a complete figure
law of pragnanz
gestalt principles altogether; perceptual organization will always be as regular, simple, and symmetric as possible
