Unit 4: Sensation/Perception Flashcards
Absolute threshold
The minimum stimulation needed to detect particular stimulus 50 percent if the time
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
Cones
Retinal receptors cells that are concentrated near the center of the retina and that function in daylight or in well-lit conditions. The cones detect fine detail and give ride to color sensations
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
Perception
The process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events
Rods
Retinal receptors that detect black, white, and gray; necessary for peripheral and twilight vision, when comes don’t respond
Opponent-process theory
The theory that opposing retinal processes (red-green, yellow-blue, white-black) enable color vision. For example, some cells are stimulate by green and inhibited by red; others are stimulated by red and inhibited by green
Fovea
The central focal point in the retina, around which the eye’s cones cluster
Cochlea
A coiled, bony, fluid-filled tube in the inner ear; sound waves traveling through the cochlear fluid trigger nerve impulses
Perceptual constancy
Perceiving objects as unchanging (having consistent shapes, size, brightness and color) even as illumination and retinal images change
Monocular cues
Depth cues, such as interposition and linear perspective, available to either eye alone
Transduction
Conversion of one form of energy into another. Ex: sights, sounds, and smell change into neural impulses our brain can interpret
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)
Binocular cues
Depth cues, such as retinal disparity, that depend on the use of two eyes
Place theory
In hearing, the theory that links the pitch we hear with the place where the cochlea’s membrane is stimulated
Retinal disparity
A binocular cue for perceiving depth: by comparing images from the retinas in the two eyes, the brain computes distance-the grater the disparity (difference) between the two images, the closer the object
Pitch
A tone’s experienced highness or lowness; depends on frequency
Bottom-up processing
Analysis that begins with the sensory receptors and works up to the brain’s integration of sensory information
Feature detectors
Nerve cells in the brain that respond to specific features of the stimulus, such as shape, angle, or movement
Gate-control theory
The theory that the spinal cord contains a neurological “gate” that blocks pain signals or allows them to pass on to the brain. The “gate” is opened by the activity of pain signaled traveling up small nerve fibers and is closed by activity in larger fibers or by information coming from the brain
Psychophysics
The study of relationships between the physical characteristics of stimuli, such as their intensity, and our psychological experience of them
Sensory adaptation
Diminished sensitivity as a consequence of constant stimulation
Signal detection theory
A theory prediction 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, motivations, and alertness
Top-down processing
Information processing guided by higher-level mental processes, as when we construct perceptions drawing on our experiences and expectations.
Accommodation (perceptual)
The process by which the eye’s lens changes shape to focus near or far objects on the retina
Frequency theory
The theory that the rate of nerve impulses traveling up the auditory nerve matches the frequency of a tone, thus enabling us to sense its pitch
Habituation
Decreasing responsiveness with repeated stimulation. As infants gain familiarity with repeated exposure to a visual stimulus, their wanes and they look away sooner
Lens
The transparent structure behind the pupil that changes shape to help focus images on the retina
Optic nerve
The nerve that carries neural impulses from the eye to the brain
Pupil
The adjustable opening in the center of the eye through which light enters
Vestibular sense
The sense of body movement and position, including the sense of balance
Blind spot
The point at which the optic nerve leaves the eye, creating a “blind” spot because no receptor cells are located there
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
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
Sensation
The process by which our sensory receptors and nervous system receive and represent stimulus energies from our environment
Subliminal
Below one’s absolute threshold for conscious awareness
