Vision: Sensory and Perceptual Processing
Light and shadow
Brightly lit objects appear closer, objects in shadows appear farther away
Cornea
Bump in front of the eye
Optic nerve
Carries visual information from the eye to the brain
Atmospheric perspective
Dust, smog, and water vapor make far objects look hazy
Gestalt psychologists
Group of German psychologists who studied how we organize sensations into meaningful patterns
Ciliary muscles
Responsible for accommodation, changing the shape of the lens
Visual association cortex
Organizes simple visual sensations, interprets and adds meaning
Linear perspective
Parallel lines appear to converge at a distance
Tetrachromats
People with a genetic mutation that causes 4 cones instead of 3, can see up to 100 million colors
Shape constancy
Perceiving an object as retaining its shape despite changes in viewing angle
Size constancy
Perceiving an object as retaining its size despite changes in distance
Brightness and color constancy
Perceiving an object as retaining the same brightness/color despite changes in lighting
Depth perception
Perceiving depth in visual images
Motion perception
Perceiving movement of objects
Perceptual constancy
Perceiving objects as remaining the same despite changes in the retinal image
Trichromatic theory
Perception of color is based on the response of three types of cones
Cones
Photoreceptors responsible for daytime vision, low sensitivity, high acuity, and color
Rods
Photoreceptors responsible for night vision, high sensitivity, low acuity, and no color
Retinal disparity
Binocular cue for depth perception, difference in retinal images of each eye
Convergence
Binocular cue for depth perception, extraocular muscles move eyes to focus
Figure-ground
Distinguishing between a figure and a background
Interposition
Objects that block our view of other objects are closer
Perceptual adaptation
Ability to adjust to changed sensory input, including an artificially displaced or inverted visual field
Blind spot
Area where the optic nerve leaves the eye, no photoreceptors
Texture gradient
Areas with sharp, detailed texture are interpreted as closer
Cataracts
Clouding of the lens, causing blurry vision
Opponent-process theory
Colors are represented in the visual system as opponent colors
Binocular cues
Cues for depth perception that require both eyes
Monocular cues
Cues for depth perception that require signals from one eye
Visual agnosia
Difficulty recognizing or naming objects that are seen, caused by damage to visual association cortex
Visible light
Electromagnetic radiation with wavelengths of ~400-700 nm
Nearsightedness
Eyeball too long, distant images focus in front of retina
Farsightedness
Eyeball too short, close images focus behind retina
Continuity
Favoring smooth or continuous paths when interpreting a series of points or lines
Closure
Filling in missing parts of a figure to see it as complete
Lens
Focuses light on the back of the eye
Common fate
Grouping elements together that are moving together
Similarity
Grouping together elements that appear similar
Proximity
Grouping together objects that are physically close to each other
Pupil
Hole through the iris
Electromagnetic radiation
Humans can detect electromagnetic radiation of a particular wavelength
Phi phenomenon
Illusion of movement created by blinking lights in quick succession
Color blindness
Inability to distinguish two or more shades in the color spectrum
Sensory restriction
Lack of sensory stimulation, leading to abnormal sensory and perceptual development
Relative size
Larger objects appear closer if we expect them to be the same size
Primary visual cortex
Receives visual information from the optic nerve, processes basic visual features
Wavelength
Refers to the frequency of a light wave
Restored vision
Regaining vision after a period of sensory restriction
Amplitude
The height of a light wave, known as brightness
Monochromatic color blindness
Total color blindness, world appears in shades of black and white
Sclera
Tough outer covering of the eye
Dichromatic color blindness
Trouble distinguishing red from green, see mostly shades of green