ch 5 - sensation and perception Flashcards
sensation
- detection of external stimuli
- responses to those stimuli
- transmission of those responses
perception
- the processing, organization, and interpretation of sensory signals in the brain
- results in an internal representation + your own conscious experience
transduction
- translation of incoming sensory info into neural signals
absolute threshold
- minimum intensity of stimulation that must occur before you experience a sensation
difference threshold
- the just noticeable difference between two stimuli
- minimum amt of change required to detect a difference 50% of the time
olfactory epithelium
- a thin layer of tissue w/ smell receptors
- transmit info to the olfactory bulb (brain center for smell)
orbitofrontal cortex
- receives info from taste, smell, and visual systems
- flavour perception
mechanoreceptors
- sensory cells in your skin and other parts of your body that detect physical changes like pressure, vibration, or stretch
- convert these physical signals into electrical signals that your brain can understand
myelinated (“a” delta) fibres
- deal w/ sharp + immediate pain (protection)
lightly or non-myelinated (“c) fibres
- deal with dull + steady pain (restoration)
gate control theory of pain
- for pain to be experienced, pain receptors must be activated
- the neural gate in the spinal cord must allow the signals through to the brain
- suggests that input from touch fibres competes with input from pain receptors, possibly preventing pain messages from reaching the brain
what happens if the neural gate is open?
- pain is experienced
what happened if the neural gate is closed?
- pain is reduced or prevented
accomodation
- muscles change the shape of the eye’s lens
- e.g, flattening for distant objects and thickening for close ones
photoreceptors
- convert energy from light particles (photons) into a chemical reaction
- produces an electrical signal
rods
- retinal cells that respond to low levels of light
- result in black and white perception
- located along edges of retina
cones
- retinal cells that respond to higher levels of light
- result in colour perception
- located in the fovea
how does visual transmission work?
- rods and cones
- bipolar, amacrine, horizontal cells
- ganglion cells/optic nerve
- thalamus
- primary visual cortex
- dorsal or ventral stream
s cones
- short wavelengths
- blues
m cones
- medium wavelengths
- greens
l cones
- long wavelengths
- reds
trichromatic theory
- the perception of colour is determined by the ratio of activity among s, m, and l cones
opponent-process theory
- there are three opposing colour pairs and if one colour in the pair is stimulated the other is inhibited
what are the colour pairs in the opponent-process theory?
- red/green
- yellow/blue
- white/black
motion sensitive neurons
- fatigue of certain motion sensitive neurons leads to motion after effects
- some of the neurons responsible for detecting movement in a particular direction get worn out or “tired” after being activated for a while
- so you can get tricked into seeing motions that aren’t actually happening
- buddha/waterfall effect
dorsal “where” stream / parietal pathway
- spatial perception
- where an object is and its spatial relation to other things
ventral “what” stream / temporal pathway
- perception and recognition of objects
figure-ground relationship
- whatever is not the focus of visual field is automatically assigned as background
illusory contours
- we perceive contours even when they don’t exist
- but something in the stimulus suggests that they’re there
proximity
- the closer two figures are, the more likely we are to group them together and see them as being part of the same object
similarity
- we group figures according to how closely they resemble each other
continuation
- we interpret intersecting lines as continuous instead of changing direction radically
closure
- we tend to complete figures w/ gaps
retinal disparity
-important cue of depth perception, caused by the distance between the eyes, which provides each eye with a slightly different image
- brain uses the disparity between these two retinal images to compute
distances
monocular depth cues
- include occlusion, relative size, familiar size, linear perspective, texture gradient, and position relative to horizon
- tricks your brain uses to judge depth and distance when you only have input from one eye
muller-lyer illusion
- perceiving two lines as different lengths when in reality they’re the same
ponzo illusion
- perceiving two lines as diff lengths when one is closer while the other is further but they’re the same
motion cues
- Objects that are farther away seem to move more
slowly than objects that are closer
bottom-up processing
- Processing starts with the raw sensory data from the environment, and your brain builds up the perception step by step
- Ex: Like assembling a puzzle without knowing what the final picture is supposed to look like—you rely on the pieces themselves
top-down processing
- your expectations inform your perceptions
- Your brain uses prior knowledge, expectations, or experience to interpret sensory information
- ex: reading messy handwriting but still understanding it because you know what words to expect in the sentence
Psychophysics
- study of relationships between the physical qualities of stimuli and the subjective responses they produce
signal detection theory
- how we’re able to decide if we can detect and sense faint, uncertain stimuli
sensory adaptation
- when your brain gets used to a constant stimulus and stops noticing it over time
- ex: you stop noticing the smell of a perfume after being around the smell for a while
audition
- the sense of hearing
agnosia
- being unable to recognize objects
propagnosia
- being unable to recognize faces
binocular cue
- a type of depth perception cue that requires both eyes to work together to judge depth and/or distance
cochlea
- the structure in the inner ear that contains auditory receptors
cornea
- clear surface at the front of the eye
- begins the process of directing light to the retina
depth perception
- The ability to use the two-dimensional image projected on the retina to perceive three dimensions
fovea
- An area of the retina that is specialized for highly detailed vision
somatosensory homonculus
- a map along the cerebral cortex of where each part of the body is processed
noci receptors
- a sensory ending that detects actual or potential tissue damage
gustation
- sense of taste
gestalt principles
- help explain how we perceive objects in our environment
iris
- brightly coloured circular muscle surrounding the pupil
lens
- clear structure behind pupil that bends light toward the retina
monocular cue
- depth cue that requires the use of only one eye
motion parallax
- closer objects appear to move faster than further objects
olfactory bulb
- one of the two structures below the frontal lobes of the brain that receive input from the olfactory receptors in the nose
olfactory nerve
- a nerve carrying olfactory information from the olfactory receptors to the olfactory bulbs
optic nerve
- the nerve exiting the retina of the eye
pupil
- opening formed by the iris
retina
- layer of visual processing cells in the back of the eye
vestibular system
- system in inner ear that provides info about body position and movement
synesthesia
- “Together sensation”
- Different sensory sensations intermingling together
- Cross wiring within the brain
contralateral organization
- hemispheres of the brain control the “opposite” sides of the body
- Right hemisphere controls left side, left hemisphere controls right side