lec 4 sensation and perception Flashcards
what is sensation?
receiving, translating, transmitting raw sensory info
external+ internal environments to
brain
-bottom-up processing
what is perception?
-selecting, organizing, interpreting sensory data
-Enables us to recognise meaningful objects
and events
-top-dow processing
what is Prosopagnosia?
-face blindness
-inability to recognize faces
sensation and perception in simple terms?
sensation: brain receives input from sensory organs
perception: brain makes sense of inputs
what are the 3 steps of sensation?
reception, transduction, transmission
what is the main idea of each step of sesation?
Reception- sensory receptors stimulated by energy
Transduction-stimulation–>neural impulses
Transmission-neural info to brain for processing
what are 2 other important conepts with respect to sensation?
Sensory Reduction and Coding
what is Sensory Reduction? what is coding?
Sensory Reduction:
Filter + analyze incoming sensations before sending neural impulses to brain
(ex dont feel clothes on body)
Coding
Neural impulses travel by different routes to different parts of the brain, allowing us to detect physical stimuli as distinct sensation
what is absolute threshold?
minimum level of stimulus intensity needed to detect a stimulus half the time
what are stimuli below the threshold considered?
subliminal
what is the strength and weakness of our ability to detect+interpret stimuli called?
threshold
what does our ability to detect weak stimuli depend on?
-psychological state
-(experiences, expectations, motivation, alertness)
what is priming? how do companies do this?
activation (often unconsciously) of certain associations, thus predisposing ones perception memory+respose of that thing
ad placements: once we see a product, we are primed to choose it next time we see it
what is the difference threshold? what is it also known as?
AKA: “just noticeable difference”
minimum difference (in colour, pitch,
weight, temperature, etc) for person
to be able to detect the difference half
the time
what is Weber’s law?
two stimuli to be perceived as
different, they must differ by a
constant PROPORTION and not a
constant amount
(e.g. 1/100th of the weight, not 2 ounces)
-Exact proportion varies depending on
the stimulus
what is the concept of sensory adaptation?
to detect novelty in surroundings, our senses tune out constant stimulus (ex ticking of clock)
does sensory adaptation apply to our vision? why or why not?
no, because our eyes are always moving, so stimulus always changing
what happens when we see light?
-eyes receive light energy, then transform it into neural message
-then brain processes into what we consciously see (colour, etc)
what are the main parts of the eye? what is their main function?
cornea- protects eye
pupil-small adjusting opening
iris (colored part)- dilates or restricts pupil in response to light intensity
lens- changes in curvature or thickness to focus on near or far objects
retina- transduction into neural impulses to send to optic nerve
optic nerve- sends neural impulses to brain
when looking at light, what does each part of the eye do?
-passes thru cornea, bends light to provide focus
-passes thru pupil controlled by iris
-passes thru lens, light is focused +inverted
-light lands on retina, then sent to optic nerve
if the image on our eye is inverted, how do we see everything right-side up?
-retina itself doesn’t see whole image
-rather, millions of receptor cells convert light energy into neural impulses
-neural impulses sent to brain, then reassembled into perceived upright image
What happens when light enters the retina
-light enters, triggering rods and cones
-photochemical reactions –> neural impulses
-neural impulses–>bipolar cells
-bipolar cells –> ganglion cells
-ganglion cells axons intertwine to form the optic nerve
where does optic nerve carry info to?
thalamus, stands ready to distribute info
what is the area missing from our retina’s in each eye called? why does this happen?
blind spot
no receptor cells where optic nerve leaves eye
how do we compensate for blindspots?
2 ways
- blind spot on eyes are in different spots, so they compensate for each other
-eyes constantly moving, so brain will fill in missing info with all the info our eyes take in
what do rods do? where are they located in retina?
-help is see black and white actions in peripheral view
-helps us see in dark
-located in periphery
why is our peripheral vision dull
several rods will share a bipolar cell, sending combined messages
what happens with rods in respect to dim light?
sensitive in dim light
b/c they share their energy output onto the single bipolar cell
true or false: cones are more common than rods
false, rods are abt 20x more common than cones
what are the functions of cones? where are they located in retina?
-sharp, colorful details in bright light
-center of retina
where do cones transmit their info?
SINGLE bipolar cell
-helps relay cone’s individual message to visual cortex
-precise info
what is the main difference b/w rods and cones?
rods: mixing of multiple signals to create single message
cone: single message from start to finish
what is wavelength/frequency? what do we perceive them as?
distance from one peak to next peak in electromagnetic waves
colour/hue
what is height/amplitude? what do we perceive it as?
high of peak in electromagnetic waves
intensity/brightness
how do we perceive high/low frequency (what colours do we see)
high frequency=bluish colours
low frequency= reddish colours
how do we perceive great/small amplitude? (what brightness do we see)
great height= bright colours
small height= dull colours
what are the primary colours of vision and light?
blue, green, red
If no one sees a tomato, is it red?
no, 2 reasons:
-tomato is everything BUT red, as it is rejects/reflects the long wavelength that is our perception of red
-tomatoes color is our mental construction of it, color doesn’t reside in objects, color is in our head, in how we perceive
what is Synesthesia?
stimulation of one sensory or cognitive pathway leads to involuntary experiences in a second sensory or cognitive pathway
ex. Words that taste like orange candy or Music that projects brilliant shimmering colors
What are the two theories about color perception?
Trichromatic and opponent process
what stage of processing does trichromatic theory occur? what is it’s processing mechanism? how does it help us determine colour?
-early in retina
mechanism: -3 diff types of cones, each sensitive to either short, medium, or long wavelengths (red, green or blue)
activity levels of the 3 different cone types compared in brain, this determines color of a stimulus (wavelengths come together to create colour)
helps to explain colourblindness
what stage of processing does opponent processing theory occur? what is it’s processing mechanism? how does it help us determine colour?
-later in visual pathway
mechanism: three mechanisms (ex cells) respond positively + negatively to specific colour pairs(red-green, blue-yellow, black-white)
colors in a pair travel on same pathway, so if one color (green) is stimulated, red is inhibited, they cannot travel on pathway at same time, this is why we never see a reddish-green color
-note that different pairs travel on different paths, so green and blue can travel at same time
-explains complementary color afterimages +prominence of yellow as primary colour
what does it really mean if an object is white?
white is actually all wavelengths of color being reflected back to us
3 types of cones being stimulated equally
what does it really mean if an object is black?
black absorbs all light, so objects seem black b/c no light being reflected back into our eyes
how do complementary color afterimages work?
if we stare at green, then white (all colours), we see red
b/c our green response are tired out, so we see opponent pair color b/c opponent system fires normally
essentially green is already inhibited, so red can fire normally
how can we explain colorblindness according to the trichromatic theory
person isn’t actually colourBLIND, they just lack functioning cones for color they cannot see
vision can be monochromatic: no color functioning or
dichromatic: two colors functioning (can’t distinguish red/green)
how do soundwaves reach the ear?
outer ear:
-sound to eardrum
in middle ear:
-hit eardrum + move hammer, anvil, + stirrup= amplify vibrations
-stirrup–> oval window of cochlea
inner ear:
-fluid move from oval window over cochlea’s “hair” receptor cells
-signals thru auditory nerves to temporal lobe
what does the amplitude of a soundwave determine? What effect does it have on the hair cells?
intensity or loudness of sound
(greater=loud, moves more hair cells)
(small=quiet, moves less hair cells)
what value of decibels can be dangerous to us if theres prolonged exposure
anything over 85 db
what does frequency in a soundwave determine?
pitch/tone
(high frequency=high pitch)
(low frequency= low pitch
what is Localization of Sounds?
we have 2 ears, sounds that reach one ear faster than the other help us to locate where sound is coming from
what are the 3 basic perceptual processes? What is the focus of each?
Selection
-attending to some sensory stimuli while
ignoring others
Organization
-assembling info into patterns that help us understand the world
- Interpretation
-how brain explains sensations
What are 3 concepts of the selection perceptual process?
Selective attention
-filtering out unimportant sensory
messages
Feature detectors
-specialized neurons that respond only
to certain sensory information
Habituation
-brain’s tendency to ignore stimuli that
remain constant
when all 3 concepts of selection are combined, what does it do?
-helps brain select info thats important for time and context
-helps not overwhelm
with respect to the perceptual process of organization, what are the 5 ways we organize sensory info?
- Form
- Depth
- Motion
(shrinking=moving away, growing=moving closer) - Constancy
(large objects appear to move slower when moving at same speed as smaller ones) - Colour
What are the 5 gestalt principles?
foreground: organization of visual field into objects+figures that stand out from background
~rules for grouping~
proximity: elements close tgt seen as part of same object
continuity: tendency to perceive smooth, simple, continuous patterns rather than discontinuous, complex ones
closure: figures w/ gaps on boarder seen as complete
similarity: groups objects w/ other objects sharing physical properties
what is the meaning of perceptual constancy? What are some constancies?
Perceiving environment as remaining the
same even when changes in sensation
happen (light, image on retina)
Constancies:
-Size & Shape
-Color & Brightness
what kind of cues does depth perception involve?
both binocular (two eyes) and monocular (one eye) cues
what are 2 binocular depth cues, what do they mean?
Retinal Disparity
-b/c distance between our eyes, different images fall on each retina
-brain compares images
-greater disparity=closer object
Convergence
-closer the object, the more our eyes are turned inward
monocular cues: what is an illusion?
False/misleading perceptions
monocular cues: how does light allow us to determine depth?
Nearby objects reflect more light than more distant objects
Given two identical objects, dimmer one appears to be farther
with respect to the perceptual process of interpretation, what are the 4 major factors?
- Perceptual adaptation
- Perceptual set
- Context effects (or frame of
reference) - Bottom-up vs. top-down processing
what is perceptual adaptation? what does it mean for visual abilities?
human brain can adapt to even extreme
changes
Visual ability to adjust to an artificially
displaced visual field (eg glasses that shift visual field)
what is a perceptual set?
Readiness to perceive in a particular manner,
based on expectations
what are context effects?
influence of environmental factors on one’s perception of a stimulus
eg. if object is surrounded by smaller objects, it will appear larger, and vice versa
what is another type of context effects?
cultural context
what is bottom up processing?
taking sensory information and assembling
+ integrating it
-what am i seeing?
what was found when researching sensory deprivation?
animals+humans NEED environmental stimulation to function normally
suggests that there is critical period for normal sensory + perceptual development to occur
what is top down processing
using models, ideas, and expectations to
interpret sensory info
-is it something ive seen before?
how is perception tied to biopsychosocial theory?
each concept comes together to form our own version of reality (perception)
