Unit 1.5 Part 1: Sensation

absolute threshold

The minimum stimulation needed to detect a particular stimulus 50% of the time.

accomodation

In vision, the process by which the lens of the eye shifts to focus on a particular object.

Amplitude

The height of a wave, which determines the loudness of a sound.

audition

The sense of hearing.

blind spot

The point at which the optic nerve leaves the eye, creating a small gap in the field of vision.

blindsight

A condition in which a blind person can respond to visual stimuli without consciously experiencing them.

bottom-up processing

Analysis that begins with sensory receptors and works up to the brain's integration of sensory information.

cochlea

A coiled, bony, fluid-filled tube in the inner ear through which sound waves trigger nerve impulses.

conduction hearing loss

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

cones

Photoreceptor cells in the retina that are responsible for color vision and fine detail.

cornea

The transparent outer layer of the eye that covers the pupil and iris and helps focus incoming light.

Dichromatism

A type of color blindness where one of the three basic color mechanisms is absent or not functioning.

difference threshold (just noticeable difference)

The minimum difference between two stimuli required for detection 50% of the time; also known as just noticeable difference (JND).

Farsightedness (Hyperopia)

A condition where distant objects can be seen clearly, but close objects appear blurry.

feature detectors

Nerve cells in the brain that respond to specific features of the stimulus, such as shape, angle, or movement.

fovea

The central focal point in the retina, around which the eye's cones cluster.

frequency

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

frequency theory

The 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. Best explains perception of low pitches.

Ganglion Cells

Neurons in the retina that relay information from the photoreceptors to the brain.

gate-control theory

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

gustation

The sense of taste.

hue

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

inner ear

The innermost part of the ear, containing the cochlea, semicircular canals, and vestibular sacs, involved in balance and hearing.

intensity

The amount of energy in a light or sound wave, which we perceive as brightness or loudness.

iris

The colored part of the eye that regulates the size of the pupil by controlling the amount of light entering the eye.

Just Noticeable Difference (JND)

The minimum difference in stimulation that a person can detect 50% of the time.

kinesthesis

The sense of one's body movement. Allows the body to move in coordinated ways without having

to look at the various parts of the body as it

moves.

lens

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

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.

Monochromatism

Complete color blindness where only shades of grey are perceived, with no ability to distinguish colors.

Nearsightedness (Myopia)

A condition where close objects are seen clearly, but distant objects are blurry.

Oleogustus

A proposed sixth taste sensation for the taste of fat.

olfaction

The sense of smell.

opponent-process theory

A theory of color vision proposing that the brain processes color information in pairs of complementary colors (e.g., red-green, blue-yellow, black-white).

optic (visual) nerve

The bundle of nerve fibers that carries visual information from the retina to the brain.

perception

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

Pheromones

Chemicals secreted by animals that influence the behavior or physiology of others of the same species. Detected by olfactory sense. Can play a role in attraction.

pitch

A tone's experienced highness or lowness; depends on frequency.

place theory

The theory that links the pitch we hear with the place where the cochlea's membrane is stimulated. Best explains perception of high pitches.

Prosopagnosia

A neurological disorder characterized by the inability to recognize familiar faces, also known as face blindness.

pupil

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

retina

The light-sensitive inner surface of the eye, containing receptor cells (rods and cones) and layers of neurons that begin the processing of visual information.

rods

Retinal photoreceptors that detect black, white, and gray; necessary for peripheral and twilight vision, when cones don't respond.

Semicircular Canals

Structures in the inner ear involved in maintaining balance and detecting head movements.

sensation

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

sensorineural hearing loss

Hearing loss caused by damage to the cochlea's hair cells or the auditory nerve.

sensory adaptation

Diminished sensitivity to an unchanging stimulus over time.

sensory interaction

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

sensory receptors

Specialized cells that detect sensory stimuli and convert them into neural impulses to be sent to the brain.

Sound Localization

The process by which the position of a sound source is determined.

Supertasters

Individuals with heightened sensitivity to all tastes and mouth sensations.

Synesthesia

A condition in which one sense is perceived through another (e.g. certain sounds sound like different colors)

top-down processing

Information processing guided by higher-level mental processes, as when we construct perceptions drawing on our experience and expectations.

transduction

The process of converting one form of energy into another, such as sensory stimuli into neural impulses.

Umami

One of the five basic tastes, often described as savory or meaty.

vestibular sense

The sense of balance. Detected by the semicircular canals & structures in the brain (e.g. cerebellum).

Visual Accommodation

The process by which the eye's lens changes shape to focus on objects at different distances.

Volley Theory

A theory of hearing which states that groups of neurons respond to sound by firing action potentials slightly out of phase with one another. Allows for perception of very high pitches.

wavelength

The distance from the peak of one wave to the peak of the next wave, determining the wave's color (in vision) or pitch (in audition).

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. The larger or stronger a stimulus, the larger the change required for a person to notice anything has changed.

Trichromatic Theory

The theory that the retina contains three different types of color receptors (cones)—red, green, and blue—that can produce any color by combining the three.

Basic Tastes

sweet, salty, sour, bitter, umami, oleogustus

Medium Tasters

Individuals with an average sensitivity to all tastes and mouth sensations.

Nontasters

Individuals with reduced sensitivity to all tastes and mouth sensations.

Phantom Limb Syndrome

the perception of sensations, including pain, in a limb that has been amputated