PSYCH 120B Midterm - Neuroanatomy & Signal Detection Theory

Sensation

Detecting physical energy like light from the world and encoding it into neural signals

Perception

Selecting, organizing, and interpreting sensory information - allows us to recognize meaning in objects and events

Dendrites

Detects incoming signals; where info from upstream neurons is received

Cell body

Collection center for info coming in through dendrites, and potentials are generated

Axon

Carries electrical signals (action potential) down the neuron

Axon terminals

Portion of the cell that connects to the dendrites of downstream cells

Synapse

Junction between neuron where they connect and send signal

Action potentials

A sudden, sharp increase in electrical potential caused by a charge from an electrode touching the axon of a neuron; Size of action potentials are fixed

4 lobes in the brain

Occipital, Temporal, Parietal, Frontal

Occipital lobe

visual processing

Temporal lobe

auditory processing

Parietal lobe

somatosensory processing

Frontal lobe

olfactory & gustatory processing

Absolute thresholds

sensory limits, e.g. what is the weakest light a participant can see 50% of the time

Difference thresholds

relative judgements, e.g. how much brighter does a light have to be for one to notice it is brighter 50% of the time (Just Noticeable Difference)

Method of constant stimuli

uses a predetermined set of trials to categorize what stimulus strengths participants can detect easily, which they can't detect, and where they transition from can to can't

Method of limits

you have a participant start with a strong or weak stimulus and increase/decrease the stimulus incrementally until they report they can no longer detect it

Method of adjustment

similar to limits, but the participant adjusts the stimulus from strong to weak or vise versa themselves

Weber's Law

JND gets larger as intensity increases; we need larger and larger differences to notice something has changed

Fechner's Law

reworking of Weber's law to solve for sensory magnitude; same relationship as Weber's law — less sensitive to change as strength increases

Steven's Law

if light intensity was physically doubled, it was perceived to be less than twice as bright, BUT if a pencil length was doubled it was perceived to be twice as long; so the relationship depends on the type of stimulus; more flexible than Weber & Fechner's laws

Catch trial

trials where you don't show them the target stimulus

Signal Detection Theory

measures how well people can distinguish between information-bearing patterns and distracting random patterns

Sensitivity

represents perceptual performance; how sensitive are you to this perceptual input

Criterion

measure of bias; are you being conservative or liberal when making perceptual decisions

Criterion to the right

conservative; less hits but also less false alarms

Criterion to the left

liberal; more hits but also more false alarms

D'

measure of sensitivity; farther apart = higher sensitivity; closer together = lower sensitivity

Correct rejection

true negative, no when there is no signal

Hit

true positive, yes when there is signal

False alarm

false positive, yes when there is no signal

Miss

false negative, no when there is a signal