chapter 6: sensation and perception Flashcards
sensation
the process by which our sensory receptors and nervous system receive and represent stimulus energies from our environment. (p. 230)
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 brains 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
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 ones absolute threshold for conscious awareness
priming
the activation, often unconsciously, of certain associations, thus predisposing ones perception, memory, or response.
sensory adaptation
diminished sensitivity as a consequence of constant stimulation. When we are constantly exposed to an unchanging stimulus, we become less aware of it because our nerve cells fire less frequently. (To experience sensory adaptation, move your watch up your wrist an inch: You will feel it—but only for a few moments.)
perceptual set
a mental predisposition to perceive one thing and not another.
a set of mental tendencies and assumptions that affects (top-down) what we hear, taste, feel and see
looking at hidden image drawings- what we see in such a drawing can be influenced by first looking at either of the two unambiguous versions
what determines our perceptual set?
Through experience we form concepts, or schemas, that organize and interpret unfamiliar information. Our preexisting schemas for monsters and tree trunks influence how we apply top-down processing to interpret ambiguous sensations.
ways emotions can influence perception
walking destinations look farther away to those who have been fatigued by prior exercise.
a hill looks steeper to those who are wearing a heavy backpack or have just been exposed to sad, heavy classical music rather than light, bouncy music. As with so many of life’s challenges, a hill also seems less steep to those with a friend beside them.
a target seems farther away to those throwing a heavy rather than a light object at it.
even a softball appears bigger when you are hitting well, observed Jessica Witt and Proffitt (2005), after asking players to choose a circle the size of the ball they had just hit well or poorly. (There’s also a reciprocal phenomenon: Seeing a target as bigger—as happens when athletes focus directly on a target—improves performance [Witt et al., 2012].)
motives also affect perception
ex: Desired objects, such as a water bottle when thirsty, seem closer (Balcetis & Dunning, 2010). This perceptual bias energizes our going for it
wavelength
the distance from one wave peak to the next which determines hue
hue
the dimension of color that is determined by the wavelength of light; what we know as the color names blue, green, etc
intensity
the amount of energy in a light wave or sound wave, which influences what we percieve as brightness or loudness. intensity is determined by a waves amplitude(height)
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
- in developmental psychology, adapting our current understandings (schemas) to incorporate new information. 2. in sensation and perception, the process by which the eyes lens changes shape to focus near or far objects on the retina
how the retina sees an image
The retina doesn’t “see” a whole image. Rather, its millions of receptor cells convert particles of light energy into neural impulses and forward those to the brain. There, the impulses are reassembled into a perceived, upright-seeming image. And along the way, visual information processing percolates through progressively more abstract levels. All this happens with astonishing speed. As a baseball pitcher’s fastball approaches home plate, the light signals work their way from the batter’s retina to the visual cortex, which then informs the motor cortex, which then sends out orders to contract the muscles—all in the 4/10ths of a second that the ball is in flight.
young-Hemholtz trichromatic (three-color) theory
the theory that the retina contains three different 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. (p. 243)
color-deficient vision
people who lack functioning red-or green-sensitive cones, or sometimes both. their vision is monochromatic(one-color) or dichromatic(two-color) instead of trichromatic, making it impossible to distinguish red and green.
afterimage effect
after staring at certain colors for a while(tiring your neural responses to them) you look at something absent of color(white) and see the opponent colors from the original image
opponent-process theory
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.
feature detectors
nerve cells in the brain that respond to specific features of the stimulus, such as shape , angle, or movement
