Chapter 4 - Sensation & Perception Flashcards
sensation
the process of detecting external events with sense organs and turning those stimuli into neural signals
receiving raw sensory input
perception
involves attending to, organizing, and interpreting stimuli that we sense
e.g. organizing diff vibrations in eardrum -> recognition: human voice
transduction
when specialized receptors transform the physical energy of the outside world into neural impulses
-> lead to our internal representation of the world
sensory receptors involved in this process differ for each sense
from stimulus/sensation to perception
stimulus -> sensory receptors -> neural impulses -> perception
transduction occurs as a bridge btwn sensory receptors & neural impulses
Doctrine of Specific Nerve Energies
1826, German physiologist Johannes Muller: States that the different senses are separated in the brain
Though, recent studies show that pathways are not immediately distinct:
perception is a skill that our brains learn through experience
orienting response
elicited by changes in our sensory and perceptual worlds -> O.R. allows us to quickly shift our attention to new or altered stimuli
eg. stepping outside a building onto busy street (traffic, bright light)
Sensory adaptation
the reduction of activity in sensory receptors with repeated exposure to a stimulus
Pro: allows us to adapt and focus on other more important events/stimuli
Con: not realizing that stimuli still affects, we are prone to eventual damage
psychophysics
Gustav Fechner (1801-1887) German physicist. Helped create this field of study that explores how physical energy such as light & sound and their intensity relate to psychological experience
popular approach: measure min. amount of stimulus needed for detection degree to which stimulus must change in strength for change to be perceptible to people
absolute threshold
minimum amount of energy or quantity of a stimulus required for it be be reliably detected at least 50% of the time it is presented
varies depending on subject (ie species) and current environment
difference threshold
the smallest difference between stimuli that can be reliably detected at least 50% of the time
e.g. add salt to your food: to cross d.t. so taste buds can register
the more intense the original stimulus, the larger amount of it that must be added for the difference threshold to be reached
Weber’s law
Ernst Weber (1795-1878) German physician: law states that the just noticeable difference between two stimuli changes as a proportion of these stimuli
Signal Detection Theory
states that whether a stimulus is perceived depends on both the sensory experience and the judgement made by the *subject
examines both **sensory process ** and decision process
subliminal perception
perception below the threshold of conscious awareness
(eg. “drink coke” on movie screen) -> can it control our behaviours?
supporting evidence prob due to participants’ expectations, though it is possible in under strict lab conditions
priming
the activation of individual concepts in long-term memory
-> priming is unlikely to create motivations that hadn’t previously existed; instead, enhance the pre-existing
figure-ground principle
Gestalt principle: objects or “figures” in our enviro tend to stand out against a background
proximity principle
Gestalt principle: we tend to treat 2+ objects in close procimity to each other as a group
proximity principle
Gestalt principle: we tend to group together individuals wearing the same uniform based on their visual similarity
Continuity principle
Gestalt principle: perceptual rule that lines and other objects tend to be continuous, rather than abruptly changing direction
closure principle
Gestalt principle: the tendency to fill in gaps to complete a whole object
Main takeaway from Gestalt concepts
characteristic of perception: we create our own organized perceptions out of the different sensory inputs that we experience
top-down processing
when our perceptions are influenced by our expectations or by our prior knowledge
reading 12 & 14 leads to expectation that ambiguous stimulus must be 13
bottom-up processing
occurs when we perceive individuals bits of sensory information (eg. sounds) and use them to construct a more complex perception (eg. a message)
occurs when you encounter something unfamiliar/difficult to recognize
perceptual set
a filer that influences what aspects of a scene we perceive or pay attention to
divided attention
paying attention to more than one stimulus or task at the same tiem
selective attention
focusing on one particular event or task
inattentional blindness
a failure to notice clearly visible events or objects because attention is directed elsewhere
wavelength
distance between peaks of a wave (re. colour perception: long wl correspond to perception of reddish colours, short wl w/ bluish colours)
-> additionally, low-amplitude waves correspond with dim colours, and high-amplidude waves are seen as bright colours
sclera
white, outer surface of the eye
cornea
clear layer that covers the front portion of the eye and also contributes to the eye’s ability to focus
pupil
regulates the amount of light that enters by changing its size; it dilates to allow more light to enter and constricts to allow less light into the eye
iris
a round muscle that adjusts the size of the pupil; it also gives the eyes their characteristic colour
lens
a clear structure that focuses light onto the back of the eye
accomodation
the lens can change its shape to ensure that light entering the eye is refracted in such a way that is focused when it reaches the back of the eye
retina
lines the inner surfact of the back of the eye. consists of specialized receptors that absorb light & send signals related to the properties of light **to the brain
optic nerve
a dense bundle of fibres that *connect to the brain
optic disc
area of the retina with no photo receptors (due to placement of the optic nerve) -> results in a blind spot
rods
photoreceptors that occupy peripheral regions of the retina; they are highly sensitive under low light levels
cones
photoreceptors that are sensitive to the different wavelengths of light that we perceive as colour
fovea
central region of the retina
dark adaptation
the process by which the rods and cones become increasingly sensitive to light under lower levels of illumination
trichromatic theory (/Young-Helmholtz theory)
maintains that colour vision is determined by three different cone types that are sensitive to short, medium, and long wavelengths of light
opponent-process theory (of colour perception)
states that we perceive colour in terms of opposing pairs
-> red to green, yellow to blue, and white to black
explains tendency of *negative afterimage *
complementary of trichromatic theory bc/ both are required to explain how we see colour
–> trichromatic: expl colour vision in terms of the activity of cones
–> opponent-process: expl what happens when ganglion cells process signals from a # of diff cones at the same time
optic chiasm
1st stop of info from the optic nerve
point at wh/ the optic nerves cross at the midline of the brain
feature detection cells
cells of the visual cortex
respond selectively to simple and specific aspects of a stimulus, such as angles and edges
-> principle location that visual imput is organized for perception
ventral stream
extends from the visual cortex to the lower part of the temporal lobe
main function: object recognition
“what” pathway
dorsal stream
extends from the visual cortex to the parietal lobe
main function: locating objects in space & allowing you to interact with them
“where” pathway
perceptual constancy
the ability to perceive objects as having constant shape, size, and colour despite changes in perspective
-> applies to shape, size, colour
t
propagnosia
‘face blindndess’ an inability to recognize faces
binocular depth cues
distances cues that are based on the differing perspectives of both eyes
convergence
a type of binocular depth cue that occurs when the eye muscles contract so that both eyes focus on a single object
retinal disparirty
the difference in relative position of an object as seen by both eyes -> provides info to the brain about depth
possible bc/ stereoscopic vision: result of overlapping visual fields
monocular cues
depth cues that we can perceive with only one eye
cues include accomodation, motion parallax
pitch
the perceptual experience of sound wave frequencies
-> loudness (function of sound wave amplitude)expressed in decibels (dB)
cochlea
a fluid-filled membrane that is coiled in a snail-like shape and contains the structures that convert sound into neural impulses
sound localization
process of ID’ing where sound comes from (handled by brainstem & midbrain structure called inferior colluiculus)
-> involves which ear the sound hits first, intensity & sound shadow
place theory of hearing
how we perceive pitch is based on the** location along the basilar membrane** that sound stimulates
high-freq sounds stimulate hair cells @ base of cochlea
low-freq **@
frequency theory
the perception of pitch is related to the frequency at which the basilar membrane vibrates
eg, 70 -Hz sound stimular hair cells 70x/second
volley principle: groups of neurons fire in alternating fashion for sounds that exceed the # of times a neuron can fire/second (1000Hz)
primary auditory cortex
major perceptual centre of the brain involved in perceiving what we hear
vestibular system
a sensory system in the ear that provides information about spatial orientation of the head as well as head motion
contains 2 groups of structures (vestibular sacs & semicircular canals)
vestibular sacs
structures that influence your ability to detect when your head is no longer in an upright position (made up of utricle and* saccule)*
semicircular canals
3 fluid-filled canals found in the inner ear that respond when your head moves in diff directions
somatosensory cortex
located in the parietal lobes of the brain (neural region associated w/ sense of touch) -> responsible for sensual experiences
haptics
the active, exploratory aspect of touch sensation and perception
kinesthesis
the sense of bodily motion and position
nociception
the activity of nerve pathways that respond to uncomfortable stimulation
fast fibres register sharp, immediate pain
**slow ** 4 chronic, dull
gate-control theory
explains our experience of pain as an interaction between nerves that transmit pain messages and those that inhibit these messages
phantom limb sensations
frequently experienced by amputees, who report pain & other sensations coming from the absent limb
gustatory system
functions in the sensation and perception of taste
oflactory system
involved in smell - the detection of airborne particles with specialized receptors located in the nose
oflactory epithelium
a thin layer of cells that are lined by sensory receptors called cilia
->cilia transmit messages directly to neurons that converge on ol. bulb
olfactory bulb
which serves as the brain’s central region for processing smells
on the bottom surface of the frontal lobes
multimodal integration
the ability to combine sensation from different modalities such as vision and hearing into a single integrated perception
