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CH 3 Griggs
Psychology: A Concise Introduction (6th Ed): Sensation & Perception
Term | Definition |
---|---|
absolute threshold | The minimum amount of energy in a sensory stimulus detected 50% of the time. |
signal detection theory | A theory that assumes that the detection of faint sensory stimuli depends not only upon a person’s physiological sensitivity to a stimulus but also upon his decision criterion for detection, which is based on nonsensory factors." |
difference threshold | The minimum difference between two sensory stimuli detected 50% of the time. The difference threshold is also sometimes referred to as the just noticeable difference, or JND." |
Weber’s law | For each type of sensory judgment that we can make, the measured difference threshold is a constant fraction of the standard stimulus value used to measure it. This constant fraction is different for each type of sensory judgment. |
Stevens’s power law | The perceived magnitude of a stimulus is equal to its actual physical intensity raised to some constant power. The constant power is different for each type of sensory judgment. |
sensory adaptation | Our sensitivity to unchanging and repetitious stimuli disappears over time. |
wavelength | The distance in one cycle of a wave, from one crest to the next. |
amplitude | The amount of energy in a wave, its intensity, which is the height of the wave at its crest. |
frequency | The number of times a wave cycles in one second. |
transduction | The conversion of physical energy into neural signals that the brain can understand. |
accommodation | In vision, the focusing of light waves from objects of different distances directly on the retina. |
nearsightedness | A visual problem in which the light waves from distant objects come into focus in front of the retina, blurring the images of these objects. |
farsightedness | A visual problem in which the light waves from nearby objects come into focus behind the retina, blurring the images of these objects. |
blindsight | A condition in which a blind person has some spared visual capacities in the absence of any visual awareness. |
rods | Receptor cells in the retina that are principally responsible for dim light and achromatic vision. |
cones | Receptor cells in the retina that are principally responsible for bright light and color vision. |
fovea | A tiny pit in the center of the retina filled with cones. |
dark adaptation | The process by which the rods and cones through internal chemical changes become more and more sensitive to light in dim light conditions. |
trichromatic theory | A theory of color vision that assumes that there are three types of cones, each only activated by wavelength ranges of light corresponding roughly to blue, green, and red. If all three are activated, we see white. Other colors are variations of activation |
additive mixtures | Direct mixtures of different wavelengths of light in which all of the wavelengths reach the retina and are added together. |
subtractive mixtures | Mixtures of wavelengths of light in which some wavelengths are absorbed (subtracted) and so do not get reflected from the mixtures to the retina. |
complementary colors | Wavelengths of light that when added together produce white. |
opponent-process theory | A theory of color vision that assumes that there are three opponent-process cell systems (red-green, blue-yellow, and black-white) and the colors in each system oppose one another in that if one color is stimulated, the other is inhibited. |
cochlea | A snail-shaped structure in the inner ear that contains the receptor cells for hearing. |
hair cells | The receptor cells for hearing. They line the basilar membrane inside the cochlea. |
nerve deafness | Hearing loss created by damage to the hair cells or the auditory nerve fibers in the inner ear. |
conduction deafness | Hearing loss created by damage to one of the structures in the ear responsible for mechanically conducting the auditory information to the inner ear. |
place theory | A theory of pitch perception that assumes that there is a specific location along the basilar membrane that will respond to a particular frequency (20,000 Hz to 20 Hz), thereby indicating the pitch to the brain. |
retina | The light-sensitive layer of the eye that is composed of three layers of cells—ganglion, bipolar, and receptor (rods and cones). |
frequency theory | A theory of pitch perception that assumes that the frequency of the sound wave is mimicked by the firing rate of the entire basilar membrane. |
volley principle | Cells taking turns firing will increase the maximum firing rate for a group of cells. |
sensation | The initial information gathering and recoding by the sensory structures. |
perception | The interpretation by the brain of sensory information. |
bottom-up processing | The processing of incoming sensory information as it travels up from the sensory structures to the brain. |
top-down processing | The brain’s use of knowledge, beliefs, and expectations to interpret sensory information. |
perceptual set | The interpretation of ambiguous sensory information in terms of how our past experiences have set us to perceive it. |
contextual effect | The use of the present context of sensory information to determine its meaning. |
figure-and-ground principle | The Gestalt perceptual organizational principle that the brain organizes sensory information into a figure or figures (the center of attention) and ground (the less distinct background). |
closure | The Gestalt perceptual organizational principle that the brain completes (closes) incomplete figures to form meaningful objects. |
subjective contour | A line or shape that is perceived to be present but does not really exist. The brain creates it during perception. |
perceptual constancy | The perceptual stability of the size, shape, brightness, and color for familiar objects seen at varying distances, different angles, and under different lighting conditions. |
depth perception | Our ability to perceive the distance of objects from us. |
retinal disparity | A binocular depth cue referring to the fact that as the disparity (difference) between the two retinal images of an object increases, the distance of the object from us decreases. |
linear perspective | A monocular depth cue referring to the fact that as parallel lines recede away from us, they appear to converge—the greater the distance, the more they seem to converge. Sometimes referred to as perspective convergence. |
interposition | A monocular depth cue referring to the fact that if one object partially blocks our view of another, we perceive it as closer to us. |