Sensations ID Terms

Definitions from AMSCO Book

Sensation

The process by which we receive physical energy from the environment and encode it into neural signals.

Transduction

The conversion of one form of energy into another.  In sensation, this is the transformation of sights, sounds, and smells into neural impulses our brain can interpret.

Wavelength

The distance from the peak of one light or sound wave to the next peak.  Wavelengths in light waves determine the hue (color) and wavelengths in sound waves determine the pitch (sound).

Intensity

The amount of its energy measured by amplitude or height.

Photoreceptor

Cells which are called rods and cones; neurons in the retina that respond to light.

Hue

The color we experience, comes in the basic colors of red, green, or blue.

Visible spectrum

The portion of the electromagnetic spectrum that is visible to the human eye; shows the band of wavelengths we can see.

Cornea

The outer layer, a transparent, convex structure that covers the front part of the eye (protects). The shape of it bends light toward the center of the eyeball. Covers the iris and pupil.

Iris

The ring of muscle tissue that forms the colored portion of the eye and that controls the size of the pupil opening.

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.  This process of the lens changing shape is called accommodation.

Aqueous Humor

Behind the pupil and the iris is a chamber, that is filled with a watery fluid.

Vitreous Humor

Light waves pass through a jellylike fluid before hitting a light-sensitive layer at the back of the eye called the retina.

Retina

The light-sensitive inner surface of the eye that contains the receptor rods and cones plus layers of neurons that begin the processing of transduction for vision.

Visual Accommodation

The eye’s ability to focus on objects at different distances by changing the lens’s shape.

Rods

Retinal receptors that detect black, white, and shades of gray that are necessary for peripheral and twilight vision when cones don’t respond.  The human eye has around 120 million rods.

Cones

Retinal receptors that are concentrated near the center of the retina that detect colors and details and that function in the daylight or in well-lit conditions.  The human eye has around 6 million cones.

Fovea

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

Optic Nerves

The nerve that carries neural impulses from the eye to the brain. 

Optic Chiasm

The point where the optic nerves cross over into the opposite side of the brain (the thalamus).

Strabismus

A condition where the eyes do not align properly, often known as “cross-eyed.”

Peripheral Vision

The eye’s ability to see things on the side of our field of vision when looking straight ahead.

Tunnel Vision

A loss of peripheral vision with retention of central vision.

Blind Spot

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

Saccade

Eyes have a reflexive, rapid movement from side to side.

Dark Adaptation

One feature our eyes possess is the ability to adapt to quickly darkening conditions such as when we go from daylight into a dark movie theater.

Rhodopsin

A light-sensitive pigment in the rods that helps the rods deal with low-light conditions.

Feature Detectors

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

Parallel Processing

The brain’s natural mode of information processing many things at once, such as color, motion, form, and depth.

Trichromatic Theory

The theory that the retina contains three different color receptors (red, green, and blue) which, when stimulated in combination can produce the perception of any color.

Opponent-Process Theory

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

Afterimage

A visual sensation that remains after the stimulus is removed; (staring at a yellow, green, and black flag and when looking away, you see red, white, and blue).

Visual Acuity

Sharpness of vision.

Myopia

A condition in which nearby objects are seen clearly but distant objects are blurred because light rays reflecting from them converge in front of the retina. (Nearsightedness)

Presbyopia

Being able to see things in the distance well but having difficulty focusing on things that are close by. (Farsightedness)

Snellen Test

The standard test for visual acuity.

Astigmatism

A cornea that is irregularly shaped creates this, which causes blurriness at any distance.

Cataracts

A clouding of the eye’s lens which results in vision difficulties. The symptoms include seeing faded colors, blurry figures, double, halos and surrounding light.

Conjunctivitis

(Pink eye) is inflammation of the conjunctiva, the transparent layer that lines the inside of the eyelid and covers the sclera (the white part of the eye).

Glaucoma

Damages the optic nerve and destroys vision, often due to increased eye pressure.

Color Blindness

The inability to perceive color differences; caused by a lack of short-, medium-, or long-wavelength cones in the fovea.

Audition

The sense of hearing.

Sound Waves

Vibrations of molecules that travel through the air. They move much more slowly than light.

Amplitude

The wave’s height. It is measured from the peak of the wave to the trough of the wave. Measures the intensity of the wave. In light it determines the brightness of the color and in sound it determines the volume.

Decibels (dB)

A unit measuring the intensity of a sound.

Pitch

a tone’s highness or lowness.

Frequency

The number of complete wavelengths that pass a point in a given time; determines the pitch.

Hertz

The unit of frequency; one cycle per second.

Echolocation

The use of sound waves and echoes to determine where objects are at or located.

Ultrasound

Beyond 20,000 Hz; Sound waves with frequencies above the normal human hearing range.

Pinna

The fleshy outside part of the ear; It has a design that allows it to catch sound waves and direct them into the ear canal.

Auditory Canal

The canal in the outer part of the ear down which sound waves travel.

Tympanic Membrane

The eardrum; vibrates when sound waves hit it.

Middle Ear

The part of the ear that transmits the eardrum’s vibrations through a piston made of three tiny bones (hammer, anvil, and stirrup) to the cochlea.

Auditory Ossicles

The three bones in the middle ear (malleus, incus, stapes) that amplify sound.

Malleus

The “hammer” bone attached to the eardrum.

Incus

The “anvil” bone, receiving vibrations from the malleus.

Stapes

The “stirrup” bone, transmitting sound to the inner ear.

Inner Ear

The innermost part of the ear that contains the cochlea, semicircular canals, and vestibular sacs (important for balance). This is where transduction happens for sound.

Cochlea

Snail-shaped organ in the inner ear that converts sound waves into neural signals.

Hair Cells

Sensory receptors in the cochlea that detect sound vibrations.

Auditory Nerve

The nerve that sends neural messages (via the thalamus) to the temporal lobe’s auditory cortex.

Place Theory

Links pitch we hear with the place where the cochlea’s membrane is stimulated. This theory can explain how we high-pitched sounds, but now how we hear low-pitch sounds because the neural signals generated by low-pitched sounds are not so neatly localized on the basilar membrane.

Frequency Theory

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

Conductive Hearing Loss

A condition in which there is a poor transfer of sounds from the tympanic membrane to the inner ear; common as people get older, but hearing aids can compensate for the loss.

Nerve Deafness

Hearing loss caused by damage of the cochlea’s receptor cells or to the auditory nerves.

Cochlear implant

A device for converting sounds into electrical signals and stimulating the auditory nerve through electrodes threaded into the cochlea.

Sensorineural hearing loss

Hearing loss caused by damage of the cochlea’s receptor cells or to the auditory nerves.

Olfaction

The sense of smell

Gustation

The sense of taste.

Somesthetic Senses

The skin senses of touch, pain, hot, and cold.

Vestibular Sense

The sense of body movements and position, including the sense of balance.

Kinesthetic Sense

The sense of the position and movement of body parts.

Chemical Senses

The sense of taste and smell, that detect chemicals in the environment.

Pheromones

Airborne chemical signals that animals can perceive; Chemical signals released by organisms that affect the behavior of other members of the same species.

Papillae

Structures on the tongue in which the taste buds are located.

Otolith Organs

Located in the inner ear; utricle and saccule; the mechanical structures in the vestibular system that sense both linear acceleration and gravity.

Proprioception

The sense of our body in space.

Sensory Conflict Theory

Explains motion sickness as the result of a mismatch among information from vision, the vestibular system, and kinesthesis

Sensory Adaptation

Diminished sensitivity as a consequence of constant stimulation.

Sensory Habituation

A behavioral response that involves shifting attention away from a stimulus and reducing the response to it.

Nociceptors

Sensory receptors that detect hurtful temperatures, pressure, or chemicals.

Visceral

Originates in the internal organs; a poorly localized, dull, or diffuse pain that arises from the abdominal organs, or viscera

Referred Pain

Felt on the surface of the body, away from the origin point; pain that is felt in a location other than where the pain originates.

Somatic Pain

Sharp, bright, and fast and comes from the skin, joints, muscles, or tendons.

Gate-Control Theory of Pain

The more neurons fire in response to a pain stimulus, the more intense the pain. The theory also says that pain messages from different nerve fibers pass through the same neural “gate” in the spinal cord. If the gate is closed by one pain message, other messages may not be able to pass through.

McGurk Effect

A perceptual phenomenon which demonstrates an interaction between hearing and vision in speech perception.

Multimodal Perception

The approach that considers how information that is collected by various individual sensory systems is integrated and coordinated