Unit 3: Sensations and Perception

sensation

sensation

sensory receptors and nervous system receive and represent stimulus energies from our environment

sensory receptors

sensory nerve endings that respond to stimuli

perception

organizing and interpreting sensory information, enabling recognition of meaningful objects and events

bottom-up processing

analysis beginning with the sensory receptors and works up to the brain’s integration of sensory information

top-down processing

information processing guided by higher-level mental processes, as when we construct perceptions drawing on experiences and expectations

selective attention

focusing of conscious awareness on a particular stimulus

inattentional blindness

failing to see visible objects when our attention is directed elsewhere

change blindness

failing to notice changes in the environment; form of inattentional blindness

transduction

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

absolute threshold

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

Subliminal

below one’s absolute threshold for conscious awareness

Difference threshold

minimum difference between two stimuli required for detection 50% of the time. (We experience the difference threshold as a just noticeable difference/jnd)

Priming

activation, often unconsciously, of certain associations, thus preparing one’s perception, memory, or response

Weber’s Law

principle that to be perceived as different, 2 stimuli must differ by a constant minimum percentage (rather than a constant amount)

Sensory adaptation

diminished sensitivity as a consequence of constant stimulation

perceptual set

mental predisposition to perceive one thing and not another

wavelength

distance from the peak of one light or sound wave to the peak of the next. Electromagnetic wavelengths vary from short blips of gamma rays to the long pulses of radio transmission

Hue

dimension of color that’s determined by the wavelength of light; what we know as the color names blue, green, etc.

Lens

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

Retina

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

Accommodation

(1) In sensation and perception, the process which eye lens change shape to focus near or far objects on the retina

(2) in developmental psychology, adapting our current understandings (schemas) to incorporate new information

Rods

retinal receptors detecting black, white, and gray, and are sensitive to movement; necessary for peripheral and twilight vision, when cones don’t respond

Cones

retinal receptors that are connected near the center of the retina and that function in daylight or in well-lit conditions. Cones detect fine detail and give rise to color sensations

Optic Nerve

nerve carrying 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 there

Fovea

central focus point in the retina, around which the eye’s cones cluster

Young-Helmholtz trichromatic (3-color theory)

theory that the retina contains 3 different color receptors-one most sensitive to red, one to green, and one to blue- which when stimulated in combination can produce the perception of color

Opponent Process Theory

theory that opposing retinal processes (red-green, blue-yellow, white-black) enable color vision.

Gestalt

organized as a whole (tendency to integrate pieces of information into meaningful wholes

Figure-Ground

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

Grouping

perceptual tendency to organize stimuli into coherent groups

Depth Perception

ability to see objects in 3D although images that strike the retina are 2D: allows judgement of distance

Visual Cliff

laboratory device for testing depth perception in infants and young animals

Binocular Cue

depth cue, like retinal disparity, depending on the use of the 2 eyes

Retinal disparity

a binocular cue for perceiving depth, by comparing retinal images from the eyes, the brain computes distance- the greater the disparity (difference) between the 2 images, the close the object

Monocular Cue

depth cue, like interposition or linear perspective, available to either eye alone

Phi phenomenon

illusion movement created when 2 or more adjacent lights blink on and off in quick succession

Perceptual Constancy

perceiving objects as unchanging (having consistent color, brightness, shape, or size) even as illumination and retinal images change

Color Constancy

perceiving familiar objects as having consistent color, even if changing illumination alters the wavelengths reflected by the object

Perceptual Adaptation

ability to adjust to changed sensory input, including an artificially displaced or even inverted visual field

Audition

sense or act of hearing

frequency

number of complete wavelengths that pass a point in a given time

Pitch

tone’s experienced highness or lowness depending on the frequency

Cochlea

a coiled, bony, fluid-filled tube in the inner ear; sound waves traveling through the cochlear fluid trigger nerve impulses

Sensorineural Hearing Loss

hearing loss caused by damage to the cochlea’s receptor or the auditory nerves; most common form of hearing loss, also called nerve deafness

Conduction Hearing loss

less common form of hearing loss, caused by damage to the mechanical system conducting sound waves to the cochlea

Place Theory

in hearing, the theory link pitch we hear with the place where the cochlea’s membrane is stimulated

Frequency Theory

in hearing, theory that the rate of nerve impulses traveling up the auditory nerve matches the frequency of a tone, thus enabling us to sense its pitch

Gate-control theory

theory that the spinal cord contains a neurological “gate” that blocks pain signals or allows them to pass on to the brain.

The “gate” is opened by the activity of pain signals traveling up the small nerve fibers and is closed by activity in larger fibers or by the information coming from the brain

Olfaction

sense of smell

kinesthesia

our movement sense-our system for sensing the position and movement of individual body arts

Vestibular sense

our sense of body movement and position enabling our sense of balance

Sensory Interaction

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

Schema

concept or framework organizing and interpreting information

Thalamus

brain’s sensory control center, located on top of the brainstem directing messages to the sensory receiving areas in the cortex and transmits replies to the cerebellum and medulla

Convergence

binocular depth cue where both eyes move inwards to focus on a nearby object

relative clarity

monocular depth cue where objects that appear sharp and clear are perceived as closer than objects that appear hazy or blurry

relative size

monocular depth cue where we perceive the distance of an object based on how its size compares to other objects of a similar known size

texture gradient

monocular depth cue where objects appear to have finer, less detailed texture as they get further away, providing a perception of depth and distance

Linear perspective

visual cue helping us perceive depth by making parallel lines appear to converge at a point in the distance creating an illusion that objects are getting farther

Interposition

monocular depth cue where one object partially overlaps another, causing the viewer to perceive the overlapped object as farther away

Pheromones

chemical signals released by animals, including humans, that can influence the behavior or physiology of other members of the same species, typically detected through the sense of smell

Gustation

sense of taste-mouths ability to tell the difference between sweet, sour, bitter, and salty properties

Taste Receptors

specialized cells located within taste buds on the tongue and other areas of the mouth that detecting chemical in food and drink, allowing us to perceive different tastes

Semicircular Canals

3 fluid-filled tubes located within the inner ear, responsible for our sense of balance and orientation, also known as the vestibular sense

Synesthesia

neurological condition that causes one sense to trigger another sense

Nearsightedness

a visual condition where a person can see close objects clearly but distant objects appear blurry because the light focuses in front of the retina instead of directly on it

Farsightedness

visual condition where a person has difficulty focusing on nearby objects due to the light focusing behind the retina, while distant objects appear clear

Photoreceptors

specialized light-sensitive cells located in the retina of the eye that convert light energy into electrical signals, allowing the brain to interpret visual information'; the 2 main types are rods
(for low-light vision) and cones (for color vision)

Pitch Perception

ability to perceive and distinguish different frequencies of sound

Amplitude

the height or intensity of a wave

Afterimages

a visual sensation that persists even after the original stimulus has been removed, often appearing in complementary colors to the original image due to the adaptation of the eye’s photoreceptor cells; this phenomenon is primarily explained by the Opponent Process Theory of color vision

Ganglion Cells

specialized neurons located in the retina of the eye that receive signals from bipolar cells and transmit visual information to the brain through their axons

Dichromatism

condition where a person only has two functioning cone types in their eyes, resulting in limited color vision

Monochromatism

condition where a person can only see shades of one color, meaning they lack the ability to perceive different colors due to only having one type of cone photoreceptor in their eyes.

Prosopagnosia

neurological condition where a person is unable to recognize familiar faces, aka “face blindness” despite having normal vision

Blindsight

neurological condition where a person can respond to visual stimuli without consciously perceiving them

Volley theroy

principle relating to the experiences of pitch to the alternating firing of groups of neurons along the basilar membrane

Sound localization

ability to identify the direction or origin of a sound source, primarily achieved by the brain interpreting differences in the timing and intensity of sound reaching each ear, allowing us to pinpoint where a sound is coming from

Cocktail party effect

ability to focus on a single conversation or voice in a noisy environment by selectively attending to one specific sound while filtering out other surrounding noises

Closure

gestalt principle describing the tendency for our brains to fill in missing information or gaps in a visual pattern to perceive a complete, whole image, even when parts are missing

Proximity

gestalt principle stating objects that are physically close together are perceived as belonging to the same group

Similarity

gestalt principle stating people tend to group objects that share similar characteristics together, perceiving them as a single unit