Chapter Six Flashcards
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.
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.
What is the rough distinction between sensation and perception?
Sensation is the bottom-up process by which your sensory receptors and nervous system receive and represent stimuli. Perception is the top-down process by which your brain creates meaning by organizing and interpreting what your senses detect.
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.
priming
the activation, often unconsciously, of certain associations, thus predisposing one’s perception, memory, or response.
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 (or jnd).
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).
Using sound as your example, explain how these concepts differ: absolute threshold, subliminal stimulation, and difference threshold.
Absolute threshold is the minimum stimulation needed to detect a particular sound (such as an approaching bike on the sidewalk behind you) 50 percent of the time. Subliminal stimulation happens when, without your awareness, your sensory system processes a sound that is below your absolute threshold. A difference threshold is the minimum difference needed to distinguish between two stimuli (such as between the sound of a bike and the sound of a runner coming up behind you).
sensory adaptation
diminished sensitivity as a consequence of constant stimulation.
Why is it that after wearing shoes for a while, you cease to notice them (until questions like this draw your attention back to them)?
The shoes provide constant stimulation. Thanks to sensory adaptation, we tend to focus primarily on changing stimuli.
perceptual set
a mental predisposition to perceive one thing and not another.
Does perceptual set involve bottom-up or top-down processing? Why?
It involves top-down processing, because it draws on your experiences, assumptions, and expectations when interpreting stimuli.
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 wave’s amplitude (height).
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, and gray, and are sensitive to movement; necessary for peripheral and twilight vision, when cones don’t respond.
cones
retinal receptors that are concentrated near the center of the retina and that function in daylight or in well-lit conditions. Cones detect fine detail and give rise to color sensations.
optic nerve
the nerve that carries neural impulses from the eye to the brain.
Some nocturnal animals, such as toads, mice, rats, and bats, have impressive night vision thanks to having many more___________(rods/cones) than___________(rods/cones) in their retinas. These creatures probably have very poor___________(color/black-and-white) vision.
rods; cones; color.
Cats are able to open their___________much wider than we can, which allows more light into their eyes so they can see better at night.
pupils
Young-Helmholtz trichromatic (three-color) theory
the theory that the retina contains three different types of color receptors—one most sensitive to red, one to green, one to blue—which, when stimulated in combination, can produce the perception of any color.
opponent-process theory
the theory that opposing retinal processes (red-green, yellow-blue, white-black) enable color vision. For example, some cells are stimulated by green and inhibited by red; others are stimulated by red and inhibited by green.