Psychology Exam 2

Sensation

detection of external stimuli and the transmission of this information to the brain

Perception

processing, organization, and interpretation of sensory signals

Sensation involves translating physical stimulus properties (light, sound, heat, pressure, chemical composition) into

electrical impulses

Transduction

conversion of sensory stimuli into signals the brain can interpret

Quality

determined by which sensory system is stimulated (stimulation of receptors in the eye signals that light is present)

Quantity

signaled by the rate of neural impulses (more intense stimulus elicits higher rate of action potentials)

Absolute Threshold

minimum stimulus intensity required in order for you to detect it 50% of the time

Difference Threshold

minimum change in stimulus intensity required for you to notice the difference

Amount of change that can be detected is a percentage of the

stimulus intensity

Sensory systems respond \__ over time to a constant stimulus

less

Pupil

opens (dilates) and closes (contracts) to control amount of light entering the eye

Iris

muscle that controls the pupil's size

Cornea

clear- lets light in, curved- focuses light as it enters

Lens

changes shape to bend light more or less (accommodation), adjustable focus

Retina

photosensitive layer at the back of the eye, contains receptors- rods, and cones

Rods

120 million per eye, very sensitive to light- work best in dark conditions, not sensitive to color, poor acuity

Cones

6 million per eye, not very sensitive to light- work best in light conditions, sensitive to color, good acuity

Fovea

area of highest acuity on the retina, contains only cones, center of vision falls on the fovea, the rest of retina contains both rods and cones, but many more rods than cones

Rods and cones contain

photo-pigment (breaks down in response to light)

Triggers action potentials in neurons that get input from rods and cones, these signals are carried to the brain by

ganglion cells

Axons form the

optic nerve

Blind Spot

where axons leave eye- no rods or cones

Optic Chiasm

crossing over half of fibers

The left visual field is processed by

the right hemisphere

Right visual field is processed by

the left hemisphere

Primary Visual Cortex

in the occipital lobes, receives input from the thalamus, the first area of the cerebral cortex to receive visual input

Ventral Pathway "What"

identifying objects and objects features

Dorsal Pathway "Where"

locating objects and perceiving motion

color is determined primarily by

wavelength

Trichromatic Theory

three cone types (three types of photopigment), sensitive to different wavelengths, pattern of activation across cone types determines perceived color

Opponent-Process Theory

there are some color vision phenomena that trichromatic theory can't explain (Ex. retinal afterimages)

Color pairings in the visual system

red with green, blue with yellow, cells that are sensitive to red and green other cells sensitive to blue and yellow

Stimulus

sound wave (pattern of air pressure changes- high-low pressure cycles)

Amplitude

corresponds to perceived loudness

Frequency

corresponds to perceived pitch, measure is hertz

Hertz (Hz)

number of cycles per second, normal human range 20Hz- 20,000 Hz

Sound wave has \__ \__ produces a series of mechanical changes that eventually lead to action potential

physical force

Auditory Perception: Steps

1 - sound wave causes the eardrum to vibrate

2 - the vibration of the eardrum causes the ossicles in the middle ear to vibrate

3 - this causes the oval window to vibrate, creating a wave to move through the fluid in the cochlea

4 - the wave moves through the basilar membrane as well

5 - hair cells on top of the basilar membrane move up and down, causing the "hairs" (cilia) to bend

6 - bending of the hair cells releases the neurotransmitter, which stimulates the auditory nerve

Semicircular Canals

found in inner ear, but not involved in hearing, role: sense orientation in space, involved in balance

Interaural Time Difference

difference between when a sound reaches one ear and when it reaches the other ear

Interaural Intensity Difference

difference between the intensity of a sound in one ear and at the other ear

Differences of sound are \__ for sources to the left or right

largest

Sound has no difference for source directly in

front or behind

Temporal Coding

1. Basilar membrane vibrates at a rate that matches the sound frequency
2. Hair cells generate action potentials at a rate that matches the sound frequency
3. Works for low frequencies (< 4,000 Hz), but not for high frequencies

Place Coding

1. Wave in the cochlea causes a wave in the basilar membrane
2. Where the wave's "peak" occurs depends on the frequency
3. High-frequency sounds: peak near the base of the cochlea
4. Low-frequency sounds: peak near the tip of the cochlea
5. Works best for high-frequency sounds (> 4,000 Hz)
6. Temporal coding and place coding work together to cover range of human hearing

Chemical Process

molecules from food (or other things) dissolved in fluid on the tongue

How do we taste things?

chemical process, stimulate taste receptors within taste buds (poorly understood), action potentials travel to thalamus, then to frontal lobes, taste also relies on other senses: smell & texture

Five basic sensations

sweet, sour, salty, bitter, umami "savory"

Supertasters

25% of the population, experience flavors more intensely, often very sensitive to bitter foods (coffee, beer, broccoli), genetic factors & a larger number of taste buds

How do we smell things?

chemical process, chemicals (odorants) enter the nasal cavity, stimulate receptors in the olfactory epithelium, pattern of activity across receptors leads to perception of smell, does NOT project to the thalamus, receptors send input to olfactory bulb

Olfactory bulb sends inputs to other brain areas, including:

prefrontal cortex-positive/negative distinction, amygdala (and hippocampus)- odor-related memories

Haptic Perception

perception of touch, temperature, and pain

Skin contains \__ that reach to the surface of the skin, some at the base of hair follicles

receptors

Stimulated receptors send input to\__ then to the somatosensory cortex

thalamus

Why pain perception?

protection from harm

Fast Fibers

sharp, immediate pain

Slow Fibers

dull, steady pain

Learning

a relatively enduring change in behavior (or cognition), resulting from experience

Nonassociative Learning

learning about a stimulus in the external world

Associative Learning

learning how stimuli, events, or behaviors are related

Observational Learning

acquiring or changing behavior as a result of seeing someone else perform the behavior "social learning"

Classical Conditioning (Pavlovian conditioning)

studied salivary response in dogs, dogs salivated at the sight of food, eventually started salivating when the lab technician entered the room

Pavlov's experiment conclusion

response acquired through experience- learned association between the lab technician and the food, tested experimentally

Unconditioned Stimulus

food for the dogs

Unconditioned Response

dog salivating due to food

Neutral Stimulus

the clicking metronome does not cause the dog to salivate

Conditioned Stimulus

the clicking metronome is presented without the food but the dog still salivates

Acquisition

learning the association between the conditioned (CS) and unconditioned stimulus (US) (best if CS occurs just before US)

Second-Order Conditioning

can learn to associate one CS with another CS

Extinction

repeatedly presents the CS without the US (metronome with no food), weakens the conditioned response

Spontaneous Recovery

after extinction, present CS, produces conditioned response- temporarily

Stimulus Generalization

Occurs when stimuli that are similar to the original stimulus are able to produce a conditioned response (Adaptive- usually beneficial to respond similarly to similar stimuli)

Stimulus Discrimination

can learn to distinguish between similar stimuli (when one is consistently associated with unconditioned stimulus and the other is not)

Evolutionary Significance

1. some pairings are easier to associate than others
2. taste and nausea: conditioned taste aversion
3. easier than pairing sound and nausea
4. evolutionary explanation: advantage to being able to associate taste and illness, because taste guides eating behavior

Phobia

an acquired fear that is out of proportion to the real threat of an object or of a situation

Theory

phobias result from generalization of fear experience

John Watson

behaviorist; believed phobias could be explained by learning principles, rejection of Freudian ideas about repressed urges as a source of phobias, tested by conditioning fear response in infant: Little Albert

Operant Conditioning

a learning process in which the consequences of an action determine the likelihood that it will be performed in the future

Reinforcer

a stimulus that follows a response and increases the likelihood that the response will be repeated (give dog treat after trick)

Skinner studied reinforcement using a

"Skinner box"

Reinforcement

strengthening behavior

Positive Reinforcement

providing a pleasant stimulus (a reward) following a desired behavior (behavior is more likely to occur again in the future)

Negative Reinforcement

removing an unpleasant stimulus following a desired behavior (Negative-removing stimulus)

Continuous Reinforcement

reinforce the behavior every time it occurs, learning occurs quickly, but tends not to last once the reinforcement stops

Partial Reinforcement

reinforce the behavior sometimes, but not every time (more realistic, effect depends on specific reinforcement schedule, learning occurs more slowly, but persists

Ratio Schedule

based on number of times behavior occurs

Interval Schedule

based on amount of time that has passed

Fixed Schedule

more predictable

Variable Schedule

less predictable

Fixed Interval Schedule

behavior occurs a lot just before reinforcement is expected, drops off immediately after

Variable Interval Schedule

time that reinforcement will occur is unpredictable

Fixed Ratio Schedule

typically produce very high rates of behavior

Variable Ratio Schedule

typically produce extremely high rates of behavior

Positive Punishment

presenting an unpleasant stimulus in order to reduce a behavior's likelihood (yelling)

Negative Punishment

removing a pleasant stimulus in order to reduce a behavior's likelihood (removing privileges)

Effective Punishment

must be reasonable, must be unpleasant, must be applied immediately after the behavior occurs

Most punishment is not used very

effectively

Reinforcement tends to be better than punishment at

changing behavior

Corporal punishment seems

especially ineffective

Vicarious Learning

likelihood of modeling behavior depends on whether the model is punished or rewarded for the behavior