Sensation and Perception 24-25

sensation

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

Transduction

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

Perception

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

absolute threshold

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

just noticeable difference (JND)

The smallest difference in the amount of stimulation that a specific sense can detect.

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)

sensory adaptation

tendency of sensory receptor cells to become less responsive to a stimulus that is unchanging

sensory interaction

the principle that one sense may influence another, as when the smell of food influences its taste

Synesthesia

when one kind of sensory stimulus evokes the subjective experience of another

visual sensory system

the complete network of physiological structures involved in vision

Retina

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

photosensitive

having a chemical, electrical, or other response to light

blind spot

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

Cornea

The clear tissue that covers the front of the eye

pupil

the adjustable opening in the center of the eye through which light enters

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

nearsightedness

a condition in which nearby objects are seen more clearly than distant objects because distant objects focus in front of the retina

Farsightedness

a condition in which faraway objects are seen more clearly than near objects because the image of near objects is focused behind the retina

rods

retinal receptors that detect black, white, and gray; necessary for peripheral and twilight vision, when cones don't respond. useful in dark adaptation

color vision

ability to distinguish colors

trichromatic theory

theory of color vision that proposes three types of cones: red, blue, and green (related to processing in the retina/eye)

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 - explains negative afterimages (related to brain and nerve processing)

photoreceptor cells

rods and cones

sensory receptor cells

specialized cells that convert a specific form of environmental stimuli into neural impulses; different for each sense organ

Fovea

the central focal point in the retina, around which the eye's cones cluster - best visual acuity and color vision, works in bright light settings

Cones

retinal receptor cells that are concentrated near the center of the retina and that function in daylight or in well-lit conditions. The cones detect fine detail and give rise to color sensations.

Three types of cones

blue (short wavelength), green (medium wavelength), red (long wavelength)

Afterimages

Sensations that linger after the stimulus is removed. Most visual afterimages are negative afterimages, which appear in reversed colors. (red/green, blue/yellow, black/white)

ganglion cells

In the retina, the specialized neurons that connect to the bipolar cells; the bundled axons of the ganglion cells form the optic nerve. (related to opponent process and negative after images)

color vision deficiency

inability to perceive color differences

Dichromatism

A type of color blindness where one of the three basic color mechanisms is absent or not functioning and it's difficult to distinguish between two colors.

monochromatism

the inability to distinguish colors; also known as color blindness

Prosopagnosia

inability to recognize faces; face blindness

Blindsight

a condition in which a person can respond to a visual stimulus without consciously experiencing it (damage to the occipital lobes, but not sub-cortical vision areas)

hair cells

The hairlike sensory receptors for sound, which are embedded in the basilar membrane of the cochlea (perform conduction)

outer ear

The part of the ear that collects sound waves; consists of the pinna, the ear canal, and the eardrum.

middle ear

the chamber between the eardrum and cochlea containing three tiny bones (hammer, anvil, and stirrup) that concentrate the vibrations of the eardrum on the cochlea's oval window

inner ear

the innermost part of the ear, containing the cochlea and hair cells, responsible for transduction

wavelength (sound)

determines pitch

amplitude (sound)

determines loudness

place theory (of hearing)

in hearing, the theory that links the pitch we hear with the place where the cochlea's membrane is stimulated (explains how we hear sounds above 5000 HZ)

volley theory (of hearing)

a theory that proposes that our brain decodes pitch by noticing the frequency at which groups of hair cells on the basilar membrane are firing (combination of place and frequency theory that explains sounds from 1000HZ-5000HZ)

frequency theory (of hearing)

the theory that the entire basilar membrane acts like a microphone, vibrating as a whole in response to a sound (hair cells will fire at the same frequency as the sound you're hearing) explains sounds under 1000HZ

sound localization

we can locate sounds based timing and loudness. hardest to do for a sound directly in front, behind , or above.

hearing difficulties

happens due to aging or damage to auditory structures.

conduction deafness

An inability to hear resulting from damage to structures of the outer or middle ear. Can be fixed with hearing aids.

sensorineural deafness

deafness that usually results from damage to the inner ear or to the auditory nerve. It can be a result of aging, exposure to loud noise, injury, disease, certain drugs or an inherited condition.

olfactory receptor cells

receive chemicals interpreted as smells

olfactory mucosa

lines the superior nasal cavity and contains smell receptors

smell

the only sense not processed in the thalamus

Pheremones

chemical signals which are found in natural body scents in humans and other species. Released by organisms to communicate with other members of their species. They are often used by animals as sexual attractants.

Gustation

sense of taste

6 tastes

sweet, sour, salty, bitter, umami, oleogustus

umami

taste for monosodium glutamate - savory like red meat, parmesan cheese, mushroom.

Oleogustus

the taste of fat

tongue, mouth, brain

where sensations of taste are processed.

olfactory bulb

the first brain structure to pick up smell information from the nose (near the limbic system)

Supertasters

people who have the highest sensitivity to all tastes, as well as mouth sensations in general, have the most number of taste receptors.

medium tasters

average number of taste buds leading to normal taste ability.

Non-tasters

People who have fewer taste buds than normal and find tastes less intense than others

sensory interaction of taste and smell

Much of taste is odor - subtle distinctions of

taste are actually smells.

Flavor is the perception not the sensation of taste.

Flavor includes temperature, texture,

appearance and smell of food. When a person can only taste with their mouth (nose closed or stuffy with mucous), the sensation of "Taste" is limited.

chemical senses

taste and smell

touch sensory system

source: pressure, warmth, cold on the skin

receptors: skin receptors detect pressure, warmth, cold, and pain

sensation of hot

stimulating nearby cold/warm receptors produces the sensation of heat

pain sensory system

ability of the body to detect tissue damage and report to the brain. Evolutionarily helpful to protect oneself.

detection of temperature

- changes of temperature are detected by thermoreceptors

- warm & cold are detected by free nerve endings - people cannot detect absolute temperature, just changes in temperature.

gate control theory of pain

The theory that pain is a product of both physiological and psychological factors that cause spinal gates to open and relay patterns of intense stimulation to the brain, which perceives them as pain. - pain feelings can be increased by attention and anxiety or negative expectations, pain feelings can be decreased by distraction, endorphins, and conflicting touch messages.

phantom limb sensation

patients who have had a limb amputated may still experience sensations such as itching, pressure, tingling, or pain as if the limb were still there

vestibular sense

the sense of body movement and position, including the sense of balance

semicircular canals

three canals within the inner ear that contain specialized receptor cells that generate nerve impulses with body movement

Vertigo

may be from a harmless problem of the inner ear (benign positional vertigo) where crystals in semicircular canals become dislodged.

motion sickness

Effect when visual and/or motor feedback is inconsistent with vestibular info

kinesthesis sense

the sense that keeps us informed about movements of the parts of the body their position in relation to each other

kinesthesis allows us to

move our body parts in coordinated ways.

bottom-up processing

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

top-down processing

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

top down processing

prior expectations, responsible for many optical illusions where our expectations confuse our reality

Schemas

conceptual frameworks a person uses to make sense of the world - part of top-down processing and perception. (internal factor that filters perceptions)

perceptual set

a mental predisposition to perceive one thing and not another. part of top-down processing and perception. (internal factor that filters perceptions)

contexts, experiences, cultural experiences and expectations

External factors that filter our perceptions of the world

Gestalt Laws of Perceptual Organization

the notion that people group and interpret stimuli in accordance with figure-ground, similarity, proximity, and closure

Gestalt: Figure Ground

Principle stating that we recognize figures (objects) by distinguishing them from the background

Gestalt: Similarity

objects that are similar are grouped together

Gestalt: Proximity

elements that are near each other are likely to be perceived as part of the same configuration

Gestalt Closure

People tend to fill in gaps or closes the edges of a incomplete figure

attention

interaction of sensation and perception that is affected by internal and external processes. focusing awareness on a narrowed range of stimuli or events

selective attention

the ability to focus on only one stimulus from among all sensory input

cocktail party effect

Ability to concentrate on one voice amongst a crowd. Especially if it is saying something you really care about. if someone across the room says your name, you might notice that too. This effect highlights how our brains selectively focus on certain sounds (like your friend's voice or your name) while ignoring others.

inattentional blindness

failure to detect stimuli that are in plain sight when our attention is focused elsewhere

change blindness

failing to notice changes in the environment due to a break in sensation/perception - ie. looking away or having someone walk in front of you.

binocular depth cues

clues about distance based on the differing views of the two eyes (retinal disparity and convergence)

retinal disparity

a binocular cue for perceiving depth by comparing images from the retinas in the two eyes, the brain computes distance—the greater the disparity (difference) between the two images, the closer the object.

convergence

A binocular cue for perceiving depth; the extent to which the eyes cross inward when focusing on an object

monocular depth cues

cues of depth perception that are available to each eye alone (relative clarity, relative size, texture gradient, linear perspective, interposition)

relative clarity

a monocular cue for perceiving depth; hazy objects are farther away than sharp, clear objects

relative size

a monocular cue for perceiving depth; the smaller retinal image is farther away

texture gradient

a monocular cue for perceiving depth; a gradual change from a coarse distinct texture to a fine, indistinct texture signals increasing distance. objects far away appear smaller and more densely packed

linear perspective

A monocular cue for perceiving depth; the more parallel lines converge, the greater their perceived distance.

interposition

if one object partially blocks our view of another, we perceive it as closer