Comprehensive Sensation and Perception: Key Concepts in Psychology

Sensation

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

Transduction

Conversion of one form of energy into another; transforming of physical energy such as sights, sounds, and smells, into neural impulses the brain can interpret.

Absolute Threshold

Minimum stimulus energy needed to detect a particular stimulus 50% of the time.

Difference Threshold

Minimum difference between two stimuli required for detection 50% of the time.

Weber's Law

Principle that, to be perceived as different, two stimuli must differ by a constant minimum percentage.

Sensory Adaptation

Diminished sensitivity as a consequence of constant stimulation.

Lens

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

Retina

Light-sensitive back inner surface of the eye, containing the receptor rods/cones plus layers of neurons that begin the processing of visual information.

Accommodation

In sensation/perception, the process by which the eye's lens changes shape to focus images of near or far objects on the retina.

Rods

Retinal receptors that detect black, white, and gray, and are sensitive to movement; necessary for peripheral/twilight vision, when cones don't respond.

Cones

Retinal receptors that are concentrated near the center of the retina and that function in daylight or in well-lit conditions; detect fine details and give rise to color sensations.

Ganglion Cells

Axons that twine together like the strands of a rope to form the optic nerve.

Optic Nerve

Nerve that carries neural impulses from the eye to the brain.

Blindspot

Point at which the optic nerve leaves the eye, creating a 'blind' spot because no receptor cells are located there.

Photoreceptors

Rods and cones in the eye that are light sensitive.

Fovea

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

Young-Helmholtz Trichromatic Theory

Theory that the retina contains 3 different types of color receptors, which when stimulated in combination, can produce perception of any color.

Monochromatic

Form of color blindness where you can only see one shade of a single color.

Dichromatic

Partial color blindness where people only see 2-3 colors.

Afterimage

After staring at a color, a visual sensation that persists after the original stimulus is removed.

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.

Phantom-Limb Sensation

Intense pain/sensation in a limb that doesn't exist.

Gustation

Our sense of taste.

Umami

A savory, meaty taste, a 5th taste sensation.

Olefaction

Our sense of smell.

Pheromones

Olfactory chemical messages that are secreted by other members of their species.

Kinesthesis

Our movement sense; our system for sensing the position/movement of individual body parts.

Vestibular Sense

Our balance sense; our sense of body movement and position that enables our sense of balance.

Sensory Interaction

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

Opponent-Process Theory

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

Blindsight

Condition in which a person can respond to a visual stimulus without consciously experiencing it.

Audition

Sense or act of hearing.

Amplitude

Height of sound waves from peaks to troughs.

Pitch

A tone's experienced highness/lowness, depends on frequency.

Wavelength

Distance between successive peaks in a wave.

Loudness

Difference in pitches in sound waves.

Sensorineural Hearing Loss

Most common form of hearing loss, caused by damage to the cochlea's receptor cells or the auditory nerves; also called nerve deafness.

Conduction Hearing Loss

Less common form of hearing loss, caused by damage to the mechanical system that conducts sound waves to the cochlea.

Place Theory

In hearing, the theory that links the pitch we hear with the place where the cochlea's membrane is stimulated.

Volley Theory

Explains how we sense low pitches; it bounces back and forth.

Frequency

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