A method to measure haptic system acuity that assesses the smallest distance at the skin at which people can perceive two separate stimuli rather than one.

A monocular depth cue consisting of vertically oriented lines that get closer to one another, creating the perception of depth.

Depth cues that require two eyes.

An adjustable, transparent mechanism in the eye that focuses incoming light.

The perceptual system through which people acquire information about objects by touching them.

Cells that are stimulated by chemical substances in food, whose activation begins the process of transmitting gustatory information to the brain.

In the study of auditory perception, a cue to the location of a sound source that is based on the difference in pressure on left and right ears produced by a sound wave coming from one side.

Interconnected parts of the body that deliver sensory and perceptual information; humans have six perceptual systems.

The tendency for a given object to be perceived as having the same color, despite changes in illumination.

The physical property of sound waves that produces variations in pitch, based on the number of vibrations that occur during any fixed period of time.

Nervous system cells that are sensitive to specific types of physical stimulation from the environment and send signals to the brain when stimulated.

A region in the rear of the brain devoted to processing visual information.

A monocular depth cue in which one object in the field of vision partly blocks another from view.

Receptor cells under the skin that convert physical stimulation into nervous-system impulses.

A region near the center of the retina that features a dense concentration of cones.

Variations in pressure that reach the ears and are converted by the auditory system into signals.

The rear wall of the eye containing nerve cells that respond to light and send signals to the brain.

The biological pathway along which information leaves the eye and moves toward the brain, formed by the long fibers of ganglion cells.

Sources of information that enable us to judge the distance between ourselves and the objects we perceive.

A branch of psychology that studies relations between physical stimuli and psychological reactions.

A monocular depth cue based on the presence within a visual image of a relatively dark area that appears to have been created by blocking a source of light.

The sound experience that we usually describe with the words “low” or “high” (such as a musical note or voice).

Rapid movements of the eyes from one position to another.

The capacity to choose the flow of information that enters conscious awareness.

Photoreceptors that are concentrated near the center of the retina and that provide visual detail and color.

A thin membrane within the ear that vibrates when struck by sound waves.

Collections of cells near the front of the brain that receive signals from olfactory receptor cells and begin the process of identifying odors.

The continuous change in visual images that occurs when organisms move through the environment.

The brain region in the parietal lobe that completes the processing of perceptual signals of taste.

A neural system that completes the biological processing needed to recognize smells.

A taste sensation that is “savory,” triggered by high protein levels in food.

The degree of distinctness, as opposed to fuzziness, of a visual image; a monocular depth cue.

The location in the visual field at which nothing is seen because light from that location projects to an area of the retina in which there are no photoreceptors; this is the retinal area where the optic nerve exits the eye.

A biological process in which physical stimuli activate cells in the nervous system, which then send nerve impulses to the brain, where processing gives rise to perceptual and sensory experience.

In the study of auditory perception, a cue to the location of a sound source that is based on the difference in time it takes a sound coming from your side to reach each ear.

The colorful eye structure that surrounds the pupil and responds to low and high light levels by dilating or constricting the pupil.

An insensitivity to one or more of the colors red, green, or blue.

The minimal variation in a physical stimulus such as light or sound that a person can detect.

The perceptual system detecting environmental information that reaches the body in the form of light.

The biological process occurring when cells at the periphery of the body detect physical stimuli.

A bundle of nerve cells that carries auditory information from the inner ear to the brain.

The subjective experience of the intensity, or strength, of an auditory experience.

The location in the brain where visual signals carried by the optic nerves cross, sending information from the left eye to the right side of the brain, and vice versa.

The perception of three-dimensional space produced by the fact that images reaching your two eyes vary slightly because your eyes are a few inches apart; a binocular depth cue.

The perception of distance.

Cells that receive visual signals and perform “computations” on them before transmitting the same signals to the visual cortex.

Receptor cells in the eye that are sensitive to stimulation by light.

The perceptual system that is sensitive to chemical substances and provides the sense of taste.

A biological mechanism for hearing with three overall parts: an outer ear, middle ear, and inner ear.

Photoreceptors that enable vision in low illumination.

Chemical signals produced and secreted by one organism and detected by another organism of the same species, triggering a distinctive reaction.

A monocular depth cue based on markings on the surface of objects in a visual scene.

Bundles of taste receptors, found primarily on the tongue but also on the roof of the mouth and throat.

The perceptual system that detects airborne chemical substances and provides the sense of smell.

People who have greater sensitivity to tastes than others.

Depth cues that are available even when we use only one eye.

The perceptual system detecting environmental information that consists of sound waves.

Auditory receptor cells in the inner ear that are responsible for transduction of sound waves.

A binocular depth cue based on the effort eye muscles must exert to look at objects very close to the face.

The distinctive “signature” of a sound, based on variations in the complexity of sound waves.

The biological process occurring when systems in the brain process sensory signals and produce awareness of sensory inputs.

The process of bringing an idea or an external stimulus into conscious awareness.

The perceptual system that detects information about the location of body parts.

The opening in the eye through which light passes.

The transparent material at the very front of the eye; its curvature begins the process of focusing light.

The visual system’s tendency to divide a scene into objects, or “figures,” that are the focus of attention and the background context.

Specialized pain receptors that are activated by harmful stimuli such as a cut or burn.

Periods when a person’s gaze is held in one location, when most visual information is picked up.

An apparatus for studying the perception of size; the room is not cubic, contrary to the visual system’s assumption, and this creates perceptual illusion involving size.

Cells that form the optic nerve and pass visual information from the retina to the brain.

Anything that smells; odorants include a variety of substances such as foods, pheromones, and chemical signals of cell damage and disease.

An illusory perception of visual motion that occurs when stationary objects flash in an alternating sequence and are perceived as a single object moving back and forth.

The theory that the spinal cord contains a biological mechanism that acts like a gate; when closed, pain signals do not reach the brain, resulting in no U. experience of pain even though there is pain receptor activity.