Perception & Sensation exam 1

Charles Bonnet syndrome def

individuals who are going blind having vivid hallucinations

naive realism def

the belief that the world is exactly as one perceives it to be

solipsism def

the belief that the real world doesn’t exist outside of one’s mind

what disproves naive realism?

illusions and hallucinations

what disproves solipsism?

solipsism cannot be disproved; unfalsifiable, vacuous, empty, sterile

middle path between solipsism and naive realism

there is a real world outside of us, but we only know about it through sensory nerve fibers

Plato’s Allegory of the Cave is analogous to what?

the shadows cast onto the cave wall are analogous to the pupil and the back of the retina

sensation and perception def

how information is extracted from the environment, interpreted, and used to guide our actions (exists in a loop)

sensation def

first contact between organisms and their environments

transduction def

taking a physical quantity of stimuli and changing it into neural activity (ex: rods and cones process light into neural activity)

perception def

conscious experience of objects and object relationships and events (recognition based on prior knowledge)

visual masking def

images shown in rapid succession to mask initial image → interrupts visual processing of first image

Fischer, Price + Haines study def

pilots do landing and takeoff in flight simulator with heads-up display, one trial where another aircraft is on the runway

Fischer, Price + Haines study results

20% of pilots completely missed runway blockage

useful field of view def

what you can glimpse from periphery in one eye fixation

why study perception?

1. intellectual curiosity drives science

2. real-world applications

3. assisting people with impaired senses

4. artificial intelligence

5. understanding animal perceptual abilities

visual prosthesis tech

glasses process visuals and send them to implant in primary visual cortex/implant in back of eyes

1. transduces light into electricity

2. stimulates brain

3. gives minimal vision to blind person

psychophysics def

the science of determining quantitative relationships between physical stimulation and psychological/perceptual experience

subliminal stimuli def

perceptual stimuli too faint to perceive

absolute threshold qualitative def

minimum amount of stimulus energy needed for a stimulus to be perceived

absolute threshold quantitative def

the stimulus intensity detected 50% of the time (s-shaped increase in detection as stimulus energy increases

three reasons to measure thresholds

1. commonly used to measure perceptual acuity

2. helps in designing machines, buildings, etc.

3. allows us to determine basic limitations of different animals

what ranges can humans hear between?

50-20,000 Hz

Gustav Fechner

father of psychophysics, has three methods for measuring thresholds

3 methods of measuring thresholds

1. method of constant stimuli

2. method of limits

3. method of adjustment

method of constant stimuli def

fixed set of stimuli with various intensities presented in random order

method of limits def

fixed set of stimuli with various intensities presented in order

method of adjustment definition

fixed set of stimuli with various intensities; participant controls stimulus intensity

pro of method of limits

easier to administer/takes less time

con of method of limits

issue with predictability → leads to overshoot bias

pro of method of constant stimuli

less predictable → less bias

con of method of constant stimuli

takes longer/difficult to administer

pro of method of adjustment

takes the shortest time out of all methods

con of method of adjustment

leads to more predictability and more bias than other methods

intrinsic light

the faint light you see in complete darkness

neural noise definition

neurons firing to create noise when no stimuli is presented

2 main issues with Fechner’s methods:

1. problem of intrinsic light

2. can’t separate true perceptual sensitivity from decision factors (bias)

overshoot bias definition

overshooting perceptual abilities due to expectations/response bias

what response will always be correct when measuring with Fechner’s methods and why?

“yes,” because there’s always stimuli presented

catch trial definition

a trial designed to catch cheaters; a trial with no stimulus

signal detection theory definition

assumes sensory stimuli are always in noise; alternative to classic threshold theory

2 different kinds of noise:

1. internal (neural) noise

2. external (environmental) noise

near threshold, to detect stimulus, what must you distinguish between?

stimulus + noise VS. only noise

criterion for response bias

yes-bias or no-bias

what’s the term for when a stimulus is present and participant responds “yes” ?

hit

what’s the term for when a stimulus is absent and participant responds “yes” ?

false alarm

what’s the term for when a stimulus is present and participant responds “no” ?

miss

what’s the term for when a stimulus is absent and participant responds “no” ?

correct rejection

what are 2 conclusions to come to when a participant only gives “correct” responses (hits or correct rejections)?

1. participant is sensitive OR

2. trials are too easy

term for someone who only gives “yes” responses

yes-man

someone is sensitive when

hit rate > false alarm rate

someone isn’t sensitive when

hit rate = false alarm rate

when someone’s hit rate < false alarm rate

they’re messing with the study OR they’ve mixed up the buttons

calculating bias definition

comparing percentages of “yes” and “no” responses

liberal definition

someone who has a yes-bias

conservative definition

someone who has a no-bias

decision criterion definition

how strong does the signal need to be to say “yes” ?