AP Psych Chapter 3

Sensation and Perception

Sensation

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

perception

the process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events

external stimuli

Things that are heard, seen, tasted, felt, or smelled

bottom-up processing

analysis that begins with the sensory receptors and works up to the brain's integration of sensory information (sensation)

top-down processing

information processing guided by higher-level mental processes, as when we construct perceptions drawing on our experience and expectations (perception)

transduction

conversion of one form of energy into another. In sensation, the transforming of stimulus energies, such as sights, sounds, and smells, into neural impulses our brains can interpret.

steps of transduction

receive, transform, deliver

sensory receptors

sensory nerve endings that respond to stimuli

Absolute threshold

the minimum stimulation needed to detect a particular stimulus 50 percent of the time

difference threshold

the minimum difference between two stimuli required for detection 50 percent of the time

How do we test for absolute threshold in a sense like audition?

a hearing specialist exposes both of your ears to varying sound levels, for each tone the test defines the pitch at which you can detect the tone 50% of the time.

Weber's Law

the principle that, to be perceived as different, two stimuli must differ by a constant minimum percentage (rather than a constant amount)

Signal Detection Theory

a theory predicting how and when we detect the presence of a faint stimulus (signal) amid background stimulation (noise). it assumes there is no single absolute threshold and that detection depends partly on a person's experience, expectation, motivation, and alertness

What does the signal detection theory depend on?

the strength of the signal, our physiological state

Subliminal Stimuli

stimuli that are below the level of conscious awareness (not detectable 50% of the time). You may not even detect them at all if they are weak

Sensory Adaptation

diminished sensitivity as a consequence of constant stimulation

What do evolutionary psychologists suggest about sensory adaptation?

once we notice and evaluate a new stimuli as non-threatening, we can pay less attention to it. This saves our attention for new incoming stimuli, or changes in existing stimuli, which can be adapting for survival

Why does sensory adaptation occur?

Being able to ignore unthreatening/unchanging stimuli leaves us free to focus on the stimuli that IS changing. Our sense receptors are alert to novelty...a new situation means we need to evaluate and assess it and check for danger. So it is functional...adaptive.

We perceive the world not exactly as it is,

but as it is useful for us to perceive it.

Selective attention

our tendency to focus on a particular stimulus among the many that are being received. one thing can be focused on at a time.

cocktail party effect

one's ability to attend one voice among a sea of other voice/face. if another voice speaks your name, they're instantly brought to consciousness (selective attention)

Things that we deem important seem to capture our attention. True or false?

True

When we attempt to multitask, in some cases, the results can be...

fatal (texting and driving & selective attention, for example)

inattentional blindness

failing to see visible objects when our attention is directed elsewhere (example: basketball-gorilla video)

Attention is powerfully...

selective

manipulation is easily achievable through what?

selective attention

change blindness

failing to notice changes in the visual environment (change deafness can occur as well, which is the same concept with hearing)

what are some examples of subliminal messages?

flashing it on the screen so quickly you cannot perceive it, but you still see it, playing something backwards, embedding one image into another, playing it a low volume masked over by other sounds

Vicary's study

subliminal advertisements were showing for coke and popcorn during a movie. everyone thought that sales in it increased, but turns out there wasn't actually an experiment happening

backmasking

a recorded message (often in songs) which has no meaning unless played in reverse

many subliminal messages feature \_______ aspects

sexual

What allows us to see subliminal messages?

perceptual sets

perceptual set

a bias or readiness to perceive certain aspects of available sensory data and to ignore others

popout

everyone notices a change during change blindness or deafness

is product placement subliminal

no

Do humans blindly obey to subliminal messages?

no

Priming

the activation, often unconsciously, of particular associations in memory

Psychophysics

the study of relationships between the physical characteristics of stimuli, such as their intensity, and our psychological experience of them

gustav fechner

absolute threshold

what do theorists of the signal detection theory study?

why people react differently to the same stimuli and why reactions vary as circumstances change

through experience, we form concepts that...

organize and interpret unfamiliar information

what affects our immediate interpretations?

immediate context, motives, and emotion

extrasensory perception (ESP)

the controversial claim that perception can occur apart from sensory input; includes telepathy, clairvoyance, and precognition

telepathy

mind to mind communication

clairvoyance

perceiving remote events

precognition

perceiving future events

psychokinesis

ability to move objects with one's mind

if ESP actually exists (which it doesn't), then...

we'd need to overturn the scientific understanding that human minds are tied to their physical brains whose perceptual experiences are built of sensations

parapsychology

the study of paranormal phenomena, including ESP and psychokinesis

do psychics actually predict the future?

no, they guess, and coincidences are bound to happen

How do we see? (feat rods and cones)

1. light entering at the back of the eye triggers photochemical reaction in rods and cones at back of retina. 2. chemical reaction in turn activates bipolar cells. 3. bipolar cells then activate ganglion cells, the axons of which converge to form the optic nerve. this nerve transmits information to the visual cortex (via thalamus) in the brain's occipital lobe

cornea

the eye's clear, protective outer layer covering the pupil and iris. Light enters the eye first through the cornea

pupil

a small adjustable opening in the center of the eye in which light passes

iris

a ring of muscle tissue that forms the colored portion of the eye around the pupil and controls the size of the pupil opening by expanding and contracting over the pupil

lens

the transparent structure behind the pupil that changes shape to help focus images on the retina

accommodation

the process by which the eye's lens changes shape to focus near or far objects on the retina

Myopia/Nearsightedness

if the lens focuses the image on a point in front of the retina, you see near objects clearly but not distant objects. it can be remedied with glasses

hyperopia/farsightedness

a result of the lens focusing light past the retina

retina

the light-sensitive inner surface of the eye, containing receptor rods and cones plus layers or neurons that begin the processing of visual information

where is the retina located?

along the back of the eye and contains the sense receptor cells (rods and cones) that will receive the incoming light waves

fovea

the central focal point in the retina, around which the eye's cones cluster. it's the area of greatest focus

what happens in the retina?

light waves are transduced into neural impulses by rods and cones, then passed to the bipolar cells and ganglion cells

rods

retinal photoreceptors that detect black, white, and gray, and are sensitive to movement. they are necessary for peripheral and twilight vision, when cones don't respond

characteristics of rods

located along the retina's outer periphery, remain sensitive in dim light, no hotline to the brain (share connections to a single bipolar cell sending a combined message to the brain), sensitive to faint light and peripheral motion

cones

retinal photoreceptors that are concentrated near the center of the retina and function in daylight or in well-lit conditions. they detect fine detail and create color sensations

characteristics of cones

cluster in and around the fovea, become unresponsive in dim light, many have their own hotline to the brain (transmitting messages to a single bipolar cell)

optic nerve

comprised of the axons of ganglion cells, it leaves through the back of the eye and carries the neural impulses from the eye to the brain

blind spot

the point at which the optic nerve leaves the eye, creating a "blind" spot because no receptor cells are located there

what happens when the optic nerve leaves the eye?

it carries the impulse to the thalamus and onto the visual cortex of the occipital lobes

feature detectors

nerve cells located in the visual cortex of the occipital lobe that respond to a scene's edges, lines, angles, and movements

what do feature detectors do?

receive information from individual ganglion cells in the retina and pass it to other cortical areas, where supercell clusters respond to more complex patterns

trichromatic color theory

the theory that the retina contains 3 different types of color receptors-red, green, blue-which, when stimulated in combination, can produce the perception of any color

how do we see? (general)

our eyes receive light and transduce it into neural messages

wavelength

the distance from the peak of one light/sound wave to the next. it varies based on different sections of the electromagnetic spectrum

hue

the dimension of color determined by the wavelength

light's amplitude (height) determines...

intensity

intensity

the amount of energy in a light wave or sound wave which influences what we perceive as brightness/loudness

What did Johannes Kepler prove?

the retina receives upside-down images of the world. it's millions of receptor cells convert particles of light energy into neural impulses and forward those to the brain, which reassembles them into an upright image

colorblindness

having a defective cone

dichromatic color vision

a form of defective color vision in which there are only two of the primary colors are perceived

colorblindness is usually sex-linked to

males

different types of colorblindness

dichromatic, monochromatic

how does color blindness prove the trichromatic theory?

individuals have color blindness in the same patterns that would line up with having RBG sensitive cones

opponent process theory

the theory that opposing retinal processes (red-green, yellow-blue, white-black) enable color vision. For example, some cells are stimulated by green and inhibited by red; others are stimulated by red and inhibited by green

opponent process theory helps to explain what effect?

after-image effect (if you stare at a light source that has a certain color and then look at a white light, you see its opponent color)

steps of color processing

1. The retina's red, green, and blue cones respond in varying degrees to different color stimuli, as the Young-Helmholtz trichromatic theory suggested. 2. the cones responses are then processed by opponent-process cells, as Hering's opponent-process theory proposed

parallel processing

the processing of many aspects of a problem simultaneously; the brain's natural mode of information processing for many functions, including vision.

how does face recognition work?

integrating information projected by your retinas to several visual cortex areas and compares it with stored information, telling your fusiform face area to recognize the face

gestalt

an organized whole. Gestalt psychologists emphasized our tendency to integrate pieces of information into meaningful wholes.

What did gestalt psychologists believe?

the whole may exceed the some of its parts, and that our brain does more than register information, it perceives it

Necker cube

individual elements of a figure that is nothing but eight blue circles, each containing three converging white lines. when we view these elements all together, however, we see a cube that sometimes reverses direction

figure-ground

the organization of the visual field into objects (the figures) that stand out from their surroundings (the ground)

grouping

the perceptual tendency to organize stimuli into coherent groups. It's how we can bring order and form to stimuli

closure

a gestalt law of grouping that states we fill in gaps to create a complete, whole object.

continuity

a gestalt law of grouping that states we perceive smooth, continuous patterns rather than discontinuous ones

proximity

a gestalt law of grouping that states we group nearby figures together

we organize by...

similarity

depth perception

the ability to see objects in three dimensions although the images that strike the retina are two-dimensional ; allows us to judge distance

visual cliff

designed by eleanor gibson and richard walk, it is a model of a cliff with a "drop off" area that is actually covered by sturdy glass. it helps to test depth perception in infants and young animals. if the infant refused to craw; on glass mimicking a cliff ending it, it showed they can perceive depth

binocular cues

depth cues, such as retinal disparity and convergence, that depend on the use of two eyes. they help us to judge distance