the process by which stimulation of a sensory receptor produces neural impulses that the brain interprets as a sound, a visual image, an odor, a taste, a pain, or other sensory image. Sensation represents the first series of steps in processing of incoming information.
a process that makes sensory patterns meaningful. It is "..." that makes these words meaningful, rather than just a string of visual patterns. To make this happen, perception draws heavily on memory, motivation, emotion, and other psychological processes.
transformation of one form of energy into another - especially the transformation of stimulus information into nerve signals by the sense organs. Without transduction, ripe tomatoes would not appear red (or pinkish-gray, in the case of tomatoes purchased at many grocery stores).
loss of responsiveness in receptor cells after stimulation has remained unchanged for a while, as when a stimulation has remained unchanged for a while, as when a swimmer becomes adapted to the temperature of the water.
the amount of stimulation necessary for a stimulus to be detected. In practice, this means that the presence or absence of a stimulus is detected correctly half the time over many trials.
the smallest amount by which a stimulus can be changed and the difference be detected half the time
just noticeable difference (JND)
same as difference threshold
this concept says that the size of a JND is proportional to the intensity of the stimulus; the JND is large when the stimulus intensity is high and is small when the stimulus intensity is low.
the magnitude of a stimulus can be estimated by the formula S=k log R, where S=sensation, R=stimulus, and k=a constant that differs for each sensory modality (sight, touch, temperature, etc).
Steven's Power Law
a law of magnitude estimation that is more accurate than Fechner's law and covers a wider variety of stimuli. It is represented by the formula S=kl, where S=sensation, k=a constant, l=stimulus intensity, and a=a power exponent that depends on the sense being measured.
signal detection theory
explains how we detect "signals," consisting of stimulation affecting our eyes, ears, nose, skin, and other sense organs. Signal detection theory says that sensation is a judgement the sensory system makes about incoming stimulation. Often, it occurs outside of consciousness. In contrast to older theories from psychophysics, signal detection theory takes observer characteristics into account.
the thin, light-sensitive layer at the back of the eyeball. The "..." contains millions of photoreceptors and other nerve cells.
light-sensitive cells (neurons) in the retina that convert light energy to neural impulses. The photoreceptors are as far as light gets into the visual system.
photoreceptors in the retina that are especially sensitive to dim light but not to colors. Strange as it may seem, they are not "..." shaped.
photoreceptors in the retina that are especially sensitive to colors but not to dim light. You many have guessed that the "..." are "..."-shaped.
the tiny area of sharpest vision in the retina
the bundle of neurons that carries visual information from the retina to the brain.
the point where the optic nerve exits the eye and where there are no photoreceptors. Any stimulus that falls on this area cannot be seen.
a psychological sensation caused by the intensity of light waves.
also called "hue." color is not a property of things in the external world. rather, it is a psychological sensation created in the brain from information obtained by the eyes from the wavelengths of visible light.
the entire range of electromagnetic energy, including radiowaves, X-rays, microwaves, and visible light.
the tiny part of the electromagnetic spectrum to which our eyes are sensitive. The visible spectrum of other creatures may be slightly different from our own.
the idea that colors are sensed by three different types of cones sensitive to light in the red, blue, and green wavelengths. The trichromatic theory explains the earliest stage of color sensation.
the idea that cells in the visual system process colors in complementary pairs, such as red or green or as yellow or blue, and green wavelengths.
sensations that linger after the stimulus is removed. Most visual afterimages are negative afterimages, which appear in reversed colors.
typically a genetic disorder (although sometimes the result of trauma, as in the case of Jonathan) that prevents an individual from discriminating certain colors. The most common form is red-green color blindness.
the number of cycles completed by a wave in a given amount of time, usually a second
the physical strength of a wave. This is usually measured from peak (top) to valley (bottom) on a graph of the wave.
the primary organ of hearing; a coiled tube in the inner ear, where sound waves are transduced into nerve messages.
a thin strip of tissue sensitive to vibrations in the cochlea. the basilar membrane contains hair cells connected to neurons. When a sound wave causes the hair cells to vibrate, the associated neurons become excited. As a result, the sound waves are converted (transduced) into nerve activity.
a sensory characteristic of sound produced by the frequency of the sound wave.
a sensory characteristic of sound produced by the amplitude (intensity) of the sound wave
the quality of a sound wave that derives from the wave's complexity (combination of pure tones). Timbre comes from the Greek word for "drum," as does the term tympanic membrane, or eardrum.
an inability to hear resulting from damage to structures of the middle or inner ear.
nerve deafness (sensorineural deafness)
an inability to hear, linked to a deficit in the body's ability to transmit impulses from the cochlea to the brain, usually involving the auditory nerve or higher auditory processing centers.
the sense of the body orientation with respect to gravity. the "..." is closely connected with the inner ear and, in fact, is carried to the brain on a branch of the auditory nerve.
the sense of body position and movement of body parts relative to each other (also called kinesthesis)
the sense of smell
chemical signals released by organisms to communicate with other members of their species. "..." are often used by animals as sexual attractants. it is unclear whether or not humans employ "..."
the sense of taste
sensory systems for processing touch, warmth, cold, texture, and pain.
an explanation for pain control that proposes we have a neural "gate" that can, under some circumstances, block incoming pain signals.
a response to a placebo (a fake drug), caused by subjects' belief that they are taking real drugs.
the meaningful product of perception - often an image that has been associated with concepts, memories of events, emotions, and motives.
cells in the cortex that specialize in extracting certain features of a stimulus.
refers to the process used by the brain to combine the results of many sensory operations into a single percept. This occurs, for example, which sensations of color, shape, boundary, and texture are combined to produce the percept of a person's face. No one knows exactly how the brain does this. Thus the binding problem is one of the major unsolved mysteries in psychology.
perceptual analysis that emphasizes characteristics of the stimulus, rather than our concepts and expectations. "Bottom" refers to the stimulus, which occurs at step one of perceptual processing.
perceptual analysis that emphasizes the perceiver's expectations, concept memories, and other cognitive factors, rather than being driven by the characteristics of the stimulus. "Top" refers to a mental set in the brain - which stands at the "top" of the perceptual processing system
the ability to recognize the same object as remaining "constant" under the different conditions, such as changes in illumination, distance or location.
you have experienced an "..." when you have a demonstrably incorrect perception of a stimulus pattern, especially one that also fools others who are observing the same stimulus.
images that are capable of more than one interpretation. There is no "right" way to see an ambiguous figure.
from a German word that means "whole" or "form" or "configuration." The Gestalt psychologists believed that much of perception is shaped by innate factors built into the brain.
the part of a pattern that commands attention. The figure stands out against the ground.
the part of a pattern that does not command attention; the background.
the Gestalt principle that identifies the tendency to fill in gaps in figures and to see incomplete figures as complete.
Laws of perceptual grouping
the Gestalt principles of similarity, proximity, continuity, and common fate. These "laws" suggest how our brains prefer to group stimulus elements together to form a percept (Gestalt).
law of similarity
the Gestalt principle that we tend to group similar objects together in our perceptions.
law of proximity
the Gestalt principle that we tend to group objects together when they are near each other. Proximity means "nearness."
law of continuity
the Gestalt principle that we prefer perceptions of connected and continuous figures to disconnected and disjointed ones.
law of common fate
the Gestalt principle that we tend to group similar objects together that share a common motion or destination
law of Pragnanz
the most general Gestalt principle, which states that the simplest organization, requiring the least cognitive effort, will emerge as the figure. "..." shares a common root with pregnant, so it carries the idea of a "fully developed figure." That is, our perceptual Gestalt, such as a complete circle - as opposed to a broken circle.
information taken in by both eyes that aids in depth perception, including binocular convergence and retinal disparity.
information about depth that relies on the input of just one eye - includes relative size, light and shadow, interposition, relative motion, and atmospheric perspective.
readiness to detect a particular stimulus in a given context - as when a person who is afraid interprets an unfamiliar sound in the night as a threat.