1.6: Sensation

Sensation

The process by which sensory receptors and the nervous system recive and represent stimulus energies from the environment.

Sensory Transduction

The conversion of stimulus energy into neural signals.

Sensory Adaptation

Reduced sensitivity to constant stimulation.

Habituation

A decrease in response to a stimulus after repeated presentations; occurs at the natural level.

Weber-Fechner Law

The principle that to perceive a difference between two stimuli, they must differ by a constant proportion.

Sensory Interaction

The principle that one sense may influence another.

Synesthesia

A condition where stimulation of one sense leads to involuntary experiences in another.

Trichromatic Theory

Theory of color vision that proposes three types of cones: red, green, and blue.

Opponent Processing Theory

Theory that opposing retinal processes enable color vision.

Monochromatism

Color blindness in which only one type of cone functions, leading to seeing only shades of gray.

Face Blindness (Prosopagnosia)

The inability to recognize familiar faces, even one's own.

Blindsight

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

Wavelength

The distance between successive peaks of a wave; determines color in vision and pitch in hearing.

Frequency

The number of complete wavelengths that pass a point in a given time; determiens pitch in hearing.

Amplitude

The height of a wave; determines brightness in vision and volume in hearing.

Sound Localization

The process by which the location of sound is determined by comparing input to both ears.

Place Theory

Theory of hearing that links pitch with the place where the cochlea's membrane is stimulated.

Frequency Theory

Theory that the rate of nerve impulses matches the frequency of a tone, enabling pitch perception.

Volley Theory

Refinement of frequency theory; groups of neurons alternate firing to achieve higher frequencies.

Sensorineural Deafness

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

Conductive Deafness

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

Pheromones

Chemical signals released by organisms to communicate with others of the same species.

Supertaster

A person with an above-average number of taste buds; experiences taste more intensly.

Medium Taster

Has an average number of taste buds and a moderate taste sensitivity.

Nontaster

Has fewer taste buds and less sensitivity to taste, especially bitterness.

Epidermis

The outermost layer of the skin that provides a waterproof barrier and creates our skin tone.

Dermis

The thick layer of living tissue below the epidermis containing blood capillaries, nerve endings, sweat glands, etc.

Hypodermis (Subcutaneous Layer)

The deepest layer of skin made up of fat and connective tissue that insulates and cushions the body.

Mechanoreceptors

Sensory receptors that respond to mechanical pressure or distortion.

Thermoreceptors

Sensory receptors that respond to changes in temperature.

Nociceptors

Sensory receptors that detect pain and harmful stimuli.

Gate Control Theory

The theory that the spinal cord contains a neurological "gate" that blocks or allow spain signals to pass to the brain.

Phantom Limb Sensation

The sensation that an ampuatated or missing limb is still attached and sometimes painful.

Vestibular Sense

The sense of body movement and position, including balance; located in the inner ear.

Kinesthesis

The system for sensing the position and movement of individual body parts.

Proprioreceptors

Sensory receptors in muscles and joints that provide information about body position and movement.

Retina

The light-sensitive inner surface of the eye, containing receptor rodsd and cones plus layers of other neurons that process visual information.

Blind Spot

The point at which the optic nerve leaves the eye where no receptor cells are located.

Visual Nerve

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

Lens

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

Nearsightedness

A condition in which nearby objects are seen more clearly than distant objects.

Farsightedness

A condition in which faraway objects are seen more clearly than near images.

Photoreceptors

Rods and cones located in the retina that convert light energy into neural signals.

Rods

Retinal receptors that detect black, white, and gray; necessary for peripheral and twilight vision.

Cones

Retinal receptor cells that are concentrated near the center of the retina and that function in daylight or in well-lit conditions.

Fovea

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

Afterimages

Visual illusions that occur after the intiial visual stimulus has been removed, typically when staring at a colored image then looking away.

Ganglion Cells

Neurons in the retina that connect to the bipolar cells; their axons form the optic nerve.

Dichromatism

A form of color blindness characterized by the inabilityto see one or more colors.