psyc 100 unit #2

sensation

detecting physical energy with our sense organs (eyes, ears, skin, nose, tongue)

perception

the brain’s interpretation of the raw sensory information

perceptions do not always match our sensations, and therefore our perceptions do not always match physical reality

do our perceptions always match our sensations?

illusion

the way we perceive a stimulus when it doesn’t match its physical reality

transduction

conversion of an external stimulus into a neural signal via sensory receptors

sensory receptors

specialized cells designed to convert a certain kind of external information into a neural signal

sensory adaptation

when sensory neurons adjust their sensitivity based on recent stimulus history

aftereffects

opposing sensory or perceptual distortions that occur after adaptation

physical stimulus → transduction via receptors → signal carried to the brain → routed through the thalamus → arrives at appropriate location in the cortex to be perceived

explain the process of converting a sensation to a perception

light & sound

what stimuli present as waves?

wave frequency

the # of waves that pass a given point in a specified time period

pitch (more frequent → higher pitch)

what is wave frequency associated with in sound?

loudness (high → louder)

what is wave amplitude associated with in sound?

color (long → red, short → blue/violet)

what is wavelength associated with in light?

brightness/intensity of color (higher amplitude → brighter color)

what is amplitude associated with in light?

psychophysics

the study of how our sensations (psychological events) correspond to physical events in the world

absolute threshold

the lowest level of a stimulus needed for the nervous system to detect a change 50% of the time

just noticeable difference (JND)

the smallest detectable difference between two stimuli

weber’s law

law that says the amount of stimulus energy required to produce a JND is a constant fraction of stimulus energy
e.g. you can tell a difference when ¼ lb. is added to a bag you’re holding that weighs 2 lb., but not when ¼ lb. is added to a 20 lb. bag

signal detection theory (SDT)

theory for how stimuli are detected under different conditions

signal

what you’re trying to detect in SDT

noise

similar stimuli that might compete with a signal and interfere with your ability to detect it

signal-to-noise ratio

the difficulty of detecting the signal depends on the strength of the signal in relation to the strength of the noise

hit: stimulus present and you say it is

miss: stimulus present and you say it isn’t

false alarm: stimulus not present and you say it is

correct rejection: stimulus not present and you say it isn’t

name the four types of signal detection and what they mean

attention

the cognitive process of selectively concentrating on one thing in the environment while ignoring other things

dichotic listening

play different information through each ear of headphones, but information is only reported from the attended ear

cocktail party effect

happens when important information pops out in a conversation that you are not attending (e.g. your name)

inattentional blindness

occurs when unattended stimuli are ignored as if they aren’t there

change blindness

a version of inattentional blindness that occurs when you fail to detect obvious changes in your environment

bottom-up processing

constructing a representation from parts and basic features

top-down processing

processing influenced by previous experience and knowledge

perceptual set

set formed when our expectations influence our perceptions

sclera

white part of eye

pupil

circular hole in eye where light enters

iris

colored portion of eye responsible for adjusting the pupil

cornea

curved, transparent layer covering the iris and pupil that helps to focus light

lens

oval shaped disc in eye that helps to bend light

accommodation

changing of the lens’ shape to focus on near/far objects

myopia (nearsightedness)

condition when your eye is too long

hyperopia (farsightedness)

condition when your eye is too short

retina

membrane at the back of the eye responsible for converting light into a neural signal (site of transduction)

fovea

central portion of retina responsible for visual acuity (clearness) & has a high density of cones

the fovea makes up around 1% of the retina, but it is highly represented in the brain

how much of the retina does the fovea take up? how does that compare to its representation in the brain?

saccades

small jerky movements of the eye to allow for rapid changes of focus (putting the fovea on a new location)

rods: respond to low levels of light, not color sensitive, more common outside of fovea

cones: sensitive to fine detail, primarily located in the fovea, color sensitive, and less plentiful than rods

the retina contains two types of photoreceptors, explain each

optic nerve

bundle of axons that travels from the retina to the brain

blind spot

the area of the retina where the optic nerve exits the eye

vitreous humor

fluid within the eye

because our brains process information contralaterally, things in the left field of vision will be perceived in the right hemisphere and vice versa - however, our eyes can pick up on things on the opposite visual field, and therefore only the corresponding stimuli/sensations will need to cross the optic chiasm, and not necessarily all info entering the left or right eye

explain the neural pathway of vision

ventral stream

“what” pathway - color, texture, shape, size

dorsal stream

“where” pathway - location, movement, spatial

our eye perceived reflected light as color
white appears when objects reflect all the light
black appears when none of the light is reflected

when light hits an object, some of it is absorbed and some reflected. explain what happens to reflected light

hue

the color of light, corresponds to wavelength

trichromatic theory

theory that states color vision is based on three primary colors: blue, green, & red, acknowledges we have 3 types of cones (S, M, L): one likes red, one likes green, and one likes blue wavelengths

opponent process theory

theory that states we perceive color in terms of three pairs of opponent colors, red-green, blue-yellow, black-white

color blindness

inability to see some or all colors, due to loss of one or more types of cones

depth perception

ability to judge distance and spatial relations

binocular disparity

each eyes sees different images, and your brain judges the depth

convergence

eyes converge to see near objects (eyes rotate in and out)

1. relative size (distant objects look smaller than closer ones)

2. texture gradient (texture is clearer on closer objects)

3. interposition (closer objects are in front of distant ones)

4. linear perspective (parallel lines converge with distance)

5. height in plane (distant objects appear higher than closer ones)

6. light & shadow (shadows tell us about form)

7. motion parallax (closer objects pass more quickly than distant ones)

explain the monocular depth cues

pinna

visible part of ear that protrudes from head

tympanic membrane

eardrum

located in the middle ear, ossicles - malleus, incus, & stapes

what are the smallest bones in the body & where are they located?

semi-circular canals

part of ear involved in balance & movement

cochlea

fluid filled, snail shaped structure that contains the sensory receptors of the auditory system

hair cells

sensory receptor cells of auditory system, embedded in basilar membrane

basilar membrane

thin strip of tissue within the cochlea

temporal theory

theory that states frequency is coded by the activity level of a sensory neuron (aka, a given hair cell fires action potentials related to the frequency of a sound wave)

place theory

theory that states different portions of the basilar membrane are sensitive for sounds of different frequencies

interaural level differences

refers to which ear feels stronger vibrations

interaural timing differences

refers to the small difference in time when each ear hears a sound

deafness

partial or complete inability to hear

perpetual constancy

idea that we perceive objects as constant, despite change in sensations that arise from those objects

gestalt principles

1. figure ground relationship: we segment our visual world into figure & ground

2. similarity: things with similar traits are grouped together

3. continuity: we see things as continuous rather than broken up

4. closure: we close segments that represent something else

5. symmetry: symmetrical objects are grouped together

6. proximity: things near each other get grouped together

rules that govern how we perceive objects as wholes within their overall context

learning

a relatively permanent change in an organism’s behavior or thoughts as a result of an experience

non-associative learning

a form of learning that involves responding to a single stimulus (one of the simplest forms of learning)

associative learning

occurs when as organism makes connections between 2 or more stimuli/events that occur together in the environment

habituation: the process of responding less strongly over time to repeated stimuli; getting used to a stimulus

• usually a neutral (not posing a threat/danger) stimulus

• adaptation of sensory receptors 

sensitization: process of responding more strongly over time to repeated stimuli

• usually a dangerous or irritating stimulus

what are the types of non-associative learning?

classical conditioning

form of associative learning in which two stimuli are repeatedly paired

unconditioned stimulus

stimulus that produces a reflexive response

unconditioned response

an automatic response that is not learned (reflex)

conditioned stimulus

initially neutral stimulus, but eventually becomes associated with unconditioned stimulus

conditioned response

automatic response (reflex) now in response to the conditioned stimulus

acquisition

learning phase

extinction

condition when conditioned stimulus appears alone & the conditioned response weakens, and then the conditioned response is eventually eliminated

spontaneous recovery

extinct conditioned response suddenly emerges again after a delay

renewal effect

when a response is extinguished when the organism is in different contexts, but the response comes back when the organism returns to the original setting

generalization

occurs when we respond to stimuli that are similar to the conditioned stimulus

discrimination

occurs when we respond to a particular stimulus but not similar stimuli

blocking

a prior association with a conditioned stimulus prevents learning of an association with another stimulus

preparedness

biological predisposition to learn some associations quicker than other associations

taste aversion conditioning

associating food with nausea, which helps avoid food that has gone bad or is poisonous

fear conditioning

negative associations can be so powerful that they’re learned extremely fast, and can happen even after a single experience

1. The intensity of the conditioned stimulus: when the CS is paired with a very strong UCS, CR will be acquired quicker

2. The temporal relationship between the conditioned stimulus and the unconditioned stimulus: conditioning us faster if the CS occurs shortly before the USCs should help organism predict that UCS is coming

3. How reliably the controlled stimulus predicts the uncontrolled stimulus: CS should reliably predict the occurrence of the UCS

4. The number of pairings of the controlled stimulus and the uncontrolled stimulus: in general, the greater the number of pairings, the stronger the conditioned response

what factors influence classical conditioning?

operant conditioning

change in voluntary behaviors as a result of the consequences

thorndike’s law of effect

law that states behavior is a function of its consequences

discriminative stimulus

any stimulus that signals the presence of reinforcement

reinforcement

increased likelihood of a behavior being repeated

punishment

decreased likelihood of a behavior being repeated

positive reinforcement

a pleasant stimulus is added to strengthen a behavior