Sensation and Perception (Modules 17-22) Flashcards
Sensation
The process by which our sensory receptors and nervous system receive and represent stimulus energies from our environment
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
Describe an example that illustrates the difference between sensation and perception.
A frog’s receptor cells in the eyes fire only in response to small, dark moving objects. If the frog is surrounded by motionless flies, it could starve to death.
Absolute Thresholds
The minimum stimulation needed to detect a particular stimulus 50% of the time
Ex. Smelling a single drop of perfume in a three-room apartment
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 detection depends on experience.
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
Ex. Liking someone more because they give you free food
Difference Threshold
The minimum difference between two stimuli required for detection 50% of the time. We experience the difference threshold as a just noticeable difference.
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)
Sensory Adaptation
Diminished sensitivity as a consequence of constant stimulation
Ex. Moving your watch up your wrist an inch and feeling it only for a few moments
Why do we have sensory adaptation – what is its important benefit?
It gives us the freedom to focus on informative changes in our environment.
Wavelength determines ___.
Frequency
Hue
The dimension of color that is determined by the wavelength of light, or the colors as we know them (blue, green, etc.)
Amplitude determines what?
Intensity of colors
Intensity
The amount of energy in a light or sound wave, which we perceive as brightness or loudness, as determined by the wave’s amplitude
Cornea
The transparent layer forming the front of the eye
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
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; necessary for peripheral and twilight vision, when cones don’t respond
Cones
Retinal receptor 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 allow color sensations.
Bipolar Cells
Neural signals from chemical changes in rods and cones activate bipolar cells.
Ganglion Cells
Bipolar cells activate ganglion cells.
Optic Nerve
The nerve that carries neural impulses from the eye to the brain
Blind Spot
The point at which the optic nerve leaves the eye, creating a “blind” spot because no receptor cells are located there
Fovea
The central focal point in the retina, around which the eye’s cones cluster
After being processed in the retina, the optic nerve carries vision information to what part of the brain?
Thalamus
Feature Detectors
Hubel and Wiesel. Nerve cells in the brain that respond to specific features of the stimulus, such as shape, angle or movement.
Parallel Processing
The processing of many aspects of a problem simultaneously; the brain’s natural mode of information processing
Ex. Recognizing a face
Young-Helmholtz Trichromatic Theory
The theory that the retina contains three different color receptors which, when stimulated in combination, can produce the perception of any color
Three colors our eyes are sensitive to according to Young-Helmholtz Trichromatic Theory
Red, Green and Blue
According to this theory, what causes colorblindness?
Lack of functioning red- or green-sensitive cones or both.
Opponent-Process Theory
Hering. The theory that opposing retinal processes enable color vision.
3 sets of colors according to Opponent-Process Theory
Red-green, yellow-blue, black-white
Afterimages
The image you see after staring at something for a while then looking at a white surface. The afterimages are in the inverse color. If the original color was red, the afterimage would be green.
Audition
The sense or act of hearing