Unit 6

Sensation

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

Sensory Receptors

Sensory nerve endings that respond to stimuli.

Perception

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

Bottom-up processing

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

Top-down processing

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

Selective attention

The focusing of conscious awareness of a particular stimulus.

Inattentional blindness

Failing to see visible objects when our attention is directed elsewhere.

Change blindness

Failing to notice changes in the environment; a form of inattentional blindness.

Transduction

Conversion of one form of energy into another. In sensation, the transforming of stimulus energies, such as sights, sounds, and smells, into neural impulses our brain can interpret.

Psychophysics

The study of relationships between the physical characteristics of stimuli, such as their intensity, and our psychological experience of them.

Absolute threshold

The minimum stimulus energy needed to detect a particular stimulus 50 percent of the time.

Signal Detection Theory

A theory predicting how and when we detect the presence of a faint stimulus (signal) amid background stimulation (noise). Assumes there is no single absolute threshold and that detection depends partly on a person’s experience, expectations, motivation, and alertness.

Subliminal

Below one’s absolute threshold for conscious awareness.

Difference Threshold

The minimum difference between two stimuli required for detection 50 percent of the time. We experience the difference threshold as a just noticeable difference.

Priming

The activation, often unconsciously, of certain associations, thus predisposing one’s perception, memory, or response.

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).

Sensory adaptation

Diminished sensitivity as a consequence of constant stimulation.

Perceptual Set

A mental predisposition to perceive one thing and not another.

Extrasensory Perception (ESP)

The controversial claim that perception can occur apart from sensory input; includes telepathy, clairvoyance, and precognition.

Parapsychology

The study of paranormal phenomena, including ESP and psychokinesis (telekinesis).

Vestibular Cortex

Sends the message of dizziness after spinning, attached to your ear. Vertigo

Wavelength

The distance from the peak of one light or sound wave to the peak of the next. Electromagnetic wavelengths vary from the short blips of gamma rays to the long pulses of radio transmission.

Hue

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

Intensity

The amount of energy in a light wave or sound wave, which influences what we perceive as brightness or loudness. Intensity is determined by the waves amplitude or height.

Cornea

The eye's clear, protective outer layer, covering the pupil and iris.

Pupil

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

Iris

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

Lens

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

Retina

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

Accommodation

The process by which the eye's lens changes shape to focus near or far objects on the retina.

Rods

Retinal receptors that detect black, white, grey