ap psych unit 4

sensation

the process by which our sensory receptors and nervous system recieve and represent stimulus energies from our environment

sensory receptors

the nerve endings that respond to sensory stimuli

perception

the process of organizing and interpreting sensory information. enables us to recognize meaningful objects + people

usually one continuous process w/ sensation

bottom up processing

analysis beginning with sensory receptors then working up to the brain

top down processing

information processing guided by prior experience/knowledge to create perception

transduction

the conversion of one form of energy into another. in sensation, it turns stimulus energy (sights/sounds/etc) into neural impulses that our brain can interpret

psychophysics

study of the relation between the physical characteristics of stimuli and our perception of them

absolute threshold

the minimum stimulus energy needed to detect a particular stimulus ~50% of the time

signal detection theory

predicts how + when we detect the presence of a faint stimulus amid background stimulation. assumes there’s no single absolute threshold and that detection depends partly on a person’s alertness, expectations, and experience

• why do we respond differently to the same stimuli?

  • how does this depend on circumstances?

subliminal

below one’s absolute threshold for conscious awareness (detected <50% of the time)

• we can still evaluate these stimuli, just not consciously

prime/priming

phenomenon where exposure (even subliminal) to one stimulus influences how a person responds to a related stimulus later.

ex. flashes of kittens before images of people lead the people to be seen more favorably

difference threshold (JND)

minimum difference between two stimuli that can be detected 50% of the time.

diff. needed increases with size/intensity of stimulus

weber’s law

says that to be perceived as different, 2 stimuli must differ from a constant minimum PERCENTAGE (rather than amt.) 

% required depends on stimulus

sensory adaptation

diminished sensitivity to a stimulus due to constant stimulation

perceptual set

mental predisposition to see one thing and not another. influenced by our experiences

wavelength

the distance from the peak of one wave to the next peak. determines the hue we see

amplitude

the height of a light wave. determines the intensity we experience

retina

light-sensitive inner corner of eye

contains rods + cones + neurons that begin the processing of visual information

accomodation

process by which the eye’s lens changes shape to focus objects on the retina

cornea

part of eye that bends light to provide focus

iris

part of eye

muscle that controls the size of the pupil

pupil

small, adjustable opening in eye

lens

focuses light rays into an image on the retina

photoreceptors

light-sensitive nerve cells in the eyes (rods and cones)

rods

photoreceptors that detect black/white/gray, are sensitive to movement, and are necessary for peripheral and low-light vision

cones

photoreceptors that detect color & fine detail but require a lot of light

how does light move thru eye

cornea → iris → pupil → lens → retina (CIPLR)

light energy hitting the retina triggers chemical changes, beginning a cascade that results in our perception

optic nerve/visual nerve

carries neural impulses from eye to brain. made of ganglion cells

blind spot

the point where the optic nerve leaves the eye. no receptors are in here! but your brain fills it in

fovea

central focal point in the retina, where the cones cluster

near sightedness

when near objects are easier to see than far objects b/c image is focused too close on retina

far sightedness

when far away objects are easier to see than close by objects because image is focused too far back on retina

younng-hemholtz trichromatic theory

the retina has 3 types of color receptors (RGB) which can produce any color when stimulated in combination

color blindness/color deficiency

condition where color-sensitive cones do not function correctly

afterimages

image that continues to appear after a period of exposure to an original image. will be in colors opposite of original image due to opponent processing

opponent process theory

opposing retinal processes (ex. white-black, red-green) enable color vision.

some cells are stimulated by green and inhibited by red + vice versa, meaning that we can’t see red and green together

how does color processing go

1. cones respond to color stimuli

2. cone info is processed by opponent processing cells

ganglion cells

specialized neurons in the retina that receive signals and transmit them through their axons

make up the optic nerve

how does information move through the eye

photoreceptor cells → bipolar cells (just rando mesengers) → ganglion cells → up optic nerve → brain

dichromatism

when a person only has 2 out of 3 types of cones functioning, so they can’t see certain colors. explained by opponent process theory

monochromatism

when a person can’t see any color and only sees in black and white

feature detectors

nerve cells in the visual cortex that respond to specific features of a stimulus (e.g. shape, angle, movement)

• receive info from ganglion cells, then pass it onto specialized areas elsewhere in brain

parallel processing

processing many aspects of a problem simultaneously.

• form, depth, color, and motion are all processed separately then put back together

gestalt

an organized whole

gestalt psychology

emphasizes our tendency to integrate pieces of info into meaningful wholes

we filter info and construct perceptions

figure ground

gestalt principle

the organization of the visual field into objects that stand out from their surroundings

when reading, the words are the figure and the white space is the ground

grouping

gestalt principle

the perceptual tendency to organize stimuli into coherent groups

can be done by proximity, continuity, closure

proximity

grouping based on which figures are near each other

continuity

grouping based on smooth patterns

closure

grouping that fills gaps to create a whole object

visual cliff

fake cliff (covered w/ glass) used to see if babies have depth perception (they do!). made fake cliff and saw if babies would walk off of it (they did not)

binocular cue

a depth cue that depends on the use of two eyes

ex. it’s harder to touch the tips of 2 pens together with one eye closed

retinal disparity

a binocular cue that compares the images from either eye and judges distance/depth by how much the images differ 

bigger difference = closer image

monocular cues

depth cues available to either eye alone

ex. relative height, interposition

phi phenomenon

an illusion of movement created when 2+ adjacent lights blink on and off in succession

perceptual constancy

perceiving objects as unchanging (save color/shape/size/etc.) even as illumination and retinal images change. top-down process

color constancy

our tendency to perceive objects as having the same color in different lights, even as the wavelengths they give off change

brightness constancy

our tendency to perceive objects as having the same level of brightness in different lights, even as the wavelengths they give off change

shape and size constancy

our ability to perceive an object’s form as constant while we receive differing images of it

perceptual adaptation

the ability to adjust to changed sensory input

ex. if you had glasses that moved everything slightly to the left, you’d adjust to it in a few minutes

audition

the sense or act of hearing

frequency

the number of times a sound wave repeats per second. determines pitch

pitch

how low/high something sounds

middle ear

the chamber between the eardrum and cochlea, containing 3 tiny bones that concentrate the vibrations of the eardrum on the cochlea’s oval window

cochlea

coiled, bony, fluid-filled tube in the inner ear. waves that travel through the fluid trigger nerve impulses

there are little hairs in the fluid and when they move, they activate nerve cells

inner ear

the innermost part of the ear. has cochlea, semicircular canals, and vestibular sacs

how do vibrations move through the ear

environment → piston in inner ear → cochlea

sensorineural deafness / nerve deafness

caused by damage to the cochlea’s receptor cells or the auditory nerve. most common form of hearing loss

may still be able to hear sound, just not as well

conduction deafness

caused by damage to the mechanical system that conducts sound waves to the cochlea. uncommon

sound localization

the process by which we perceive and identify where a sound came from in our environment. need to combine many cues to do this!

cochlear implant

device for converting sounds into electrical signals + stimulating the auditory nerve through electrodes threaded into the cochlea

• for those with nerve deafness because that can’t be reversed

place theory

links the pitch we hear with the place where the cochlea’s membrane is stimulated.

• therefore the brain determines pitch by recognizing where a neural signal is coming from

• theory doesn’t work for low pitched sounds because they vibrate many areas of the cochlea

frequency theory

says that the rate of auditory impulses traveling up the auditory nerve matches the frequency of a tone, allowing us to sense pitch

• nerves can’t fire more than 1000x/sec though so how do we hear frequencies above 1000 waves/sec?

volley theory

helps frequency theory

says that neurons can alternate firing to generate combined frequencies grater than 1000x/sec

biological influences of pain

• activity in the fibers of the spinal cord

• genetic differences in endorphin production

• brain’s interpretation of CNS activity

gate control theory

the spinal cord contains a neurological ‘gate’ that blocks pain signals or allows them to go through to the brain

what opens the gate (gate control theory)

pain signals going up small nerve fibers in the spinal cord

what closes the gate (gate control theory)

activity in large nerve fibers in the spinal cord, signals from the brain (ex. distraction)

psychological influences of pain

• expectations

• attention to pain

• learning based on experience

social-cultural influences on pain

• cultural expectations

• empathy for others’ pain

• presence of others

phantom limb sensation

pain/discomfort in a limb that’s not there / has been amputated, as if it’s still present. ranges from mild to severe

placebo

false drugs that can trick the CNS into reducing pain (by reducing attention + responses to pain)

hypnosis

when a hypnotist suggests to a person that certain perceptions, thoughts, feelings, or behaviors will spontaneously occur. can make people not feel pain

might work bc it’s a dual-processing state of dissociation, or because it changes our selective attention

dissociation

split in consciousness, allowing some thoughts/behaviors to coexist with others

posthypnotic suggestions

suggestions made during hypnosis to be carried out when one is no longer hypnotized

selective attention

our ability to focus on only some things

umami

savory, meaty taste. ex. MSG

super tasters

people who have more taste buds than most and experience more intense flavors

medium tasters

people who have an average number of taste buds

non tasters

have fewer taste buds and don’t experience flavor as intensely

taste receptors

sensory cells on the taste buds of the tongue that allow us to perceive different tastes

reproduce pretty often and decrease in # + sensitivity over time

olfaction

the sense of smell

thalamus

part of brain that messages from every sense except for smell goes through

pheromones

messenger molecules secreted by animals. we needed to smell them pre-thalamus so smell info doesn’t go through the thalamus

gustation

the sense of taste

oleogustus

a fatty taste

kinesthesia

the system for sensing the position and movement of individual body parts

allows you to eat, walk, stand up, and more! interaction between vision, touch, and inner ear

vestibular sense

sense of body position and movement, including balance

semicircular canals

in the inner ear, filled with fluid and act as gyroscopes, helping with balance

sensory interaction

principle that one sense may influence another

ex. things taste different when you can’t smell!