AP Psychology Unit 3

• Sensation


  a process where sensory receptors detect stimuli from the environment and it enters the nervous system
• Perception


  a process where sensory information is interpreted, enabling us to recognize meaningful objects and events
• Bottom-up processing


  the brain processing incoming sensory information to create a complete perception
• Top-down processing


  information processing guided by memory and experience; we see what we expect to see
• Selective attention


  when we focus our attention on just one stimuli that gets encoded, all other stimuli is not encoded
• Inattentional Blindness


  failing to see visible objects when our attention or focus is directed elsewhere
• Change blindness


  failing to notice changes in the visual environment
• Selective inattention


  we can only focus on one thing at a time, so we do not sense stimuli that we are not paying attention to
• Psychophysics


  the study of relationships between the physical characteristics of stimuli, such as their intensity, and our psychological experience of them
• 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 brains can interpret.
• Absolute threshold


  the minimum stimulation needed to detect a particular stimulus 50% of the time
• Difference threshold (Just Noticeable Difference)


  the minimum difference between two stimuli required for detection 50% of the time
• Signal detection theory


  the response to a stimulus depends both on a person's sensitivity to the stimulus in the presence of noise and on a person's response criterion
• Weber's law


  to be able to tell the difference between two stimuli, the stimuli must differ by a constant minimum percentage
• Subliminal stimuli


  stimuli that are not detectable at least 50% of the time; they are below your absolute threshold
• Priming


  the activation of certain associations; they predispose you to a certain perception, memory, or response
• Sensory Adaptation


  diminished sensitivity to stimulus as a consequence of constant stimulation
• short light wavelength


  high frequency, Bluish color
• long light wavelength


  low frequency, reddish colors
• great light amplitude


  bright colors
• small light amplitude


  dull colors
• Cornea


  clear, protective outer layer, light first enters the eye here
• Pupil


  small, adjustable opening in the center of the eye through which light passes; dilates in low light, contracts in bright light
• Iris


  colored ring of muscle tissue that controls the size of the pupil by expanding and contracting
• Lens


  transparent structure behind the pupil that changes shape to help focus images on the retina
• Accommodation


  the lens changes shape to focus images
• Retina


  light-sensitive inner surface of the eye, containing the receptor rods and cones
• Rods


  photoreceptors sensitive to black, white, and movement; used in peripheral and night vision
• Cones


  found in the center of the retina, function in daylight and detect color and detail
• Fovea


  center of the retina, has many cones, area of great sharpness and focus
• Optic Nerve


  axons of the retinal cells, leaves through the back of the eye towards 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
• How the optic nerve works

  the optic nerve carries impulse to the thalamus and the visual cortex (in occiptal lobe)
• Young-Helmholtz Trichromatic Theory of Color Perception


  retina contains three types of color receptors (cones), red, green, and blue; when combined, they can produce any color
• Hering Opponent-Process Theory

  cone photoreceptors are paired together (red-green, blue-yellow, white-black) to enable color vision. Activation of one color of the pair inhibits activation of the other.
• How does color processing occur?

  1. The retina's red, green, and blue cones respond in varying degrees to different color stimuli, as the Young-Helmholtz trichromatic theory suggested.

  2. The cones' responses are then processed by opponent-process cells, as Hering's opponent-process theory proposed.
• Feature detectors


  special cells which respond to edges, lines, angles, and movements; located in the visual cortex
• discovery of feature detectors


  Hubel and Wiesel discovered existence of feature detectors by showing images to cats while measuring the responses to movements of specific lines
• Parallel Processing


  processing many features of a visual scene simultaneously; detecting motion, form, depth, and colors
• Gestalt Psychology


  a psychological approach that emphasizes that we often perceive the whole rather than the sum of the parts