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Sensation and Perception (Perceptual Illusions (Motion Illusions…

- - - - process of converting outside stimuli, such as light, into neural activity
      - turning outside stimuli into
        neural activity
    - - specialized forms of neurons
      - Stimulated by different kinds of energy rather than neurotransmitters
    - - Signals from various sensory organs are processed in wrong cortical areas
        
        Result: sense information is interpreted as more
        than one sensation
      - Examples
        
        Grapheme-color: letters/numbers (colors)
        
        Lexical-gustatory: words/sounds (tastes)
  - - - Is the lowest level of stimulation that a person can consciously detect 50 percent of the time the stimulation is present.
  - - - the way the brain deals with unchanging information from the environment.
      - the tendency of the brain to stop
        attending to constant, unchanging information
    - - another process by which constant, unchanging information from the sensory receptors is effectively ignored
      - the tendency of sensory receptor cells to become less responsive to a stimulus that is unchanging
        
        Microsaccades prevent eyes from adapting
    - - If there is an amputated limb the physical stimulation is not possible
      - brain responds as though stimulation occurred
- - - - Color
        
        Largely determined by the length of the wave
      - Saturation
        
        purity of the color people perceive
      - Brightness
        
        determined by the amplitude of the wave
        -how high or how low the wave actually is
    - - From front to back: The parts of the eye
        
        Light enters the eye directly from a source (such as the sun) or indirectly by reflecting off of an object.
        
        Light bends as it passes through substances of different densities, through a process known as re- fraction.
        
        Pathway of light through the eye
        
        Cornea -> Pupil -> Lens -> Retina
      - Cornea
        
        surface of the eye is covered in a clear membrane
        
        is the structure that focuses most of the light coming into the eye
      - Aqueous humor
        
        watery fluid
        
        continually replenished and supplies nourishment to the eye
      - Pupil
        
        Hole where the light from the visual image then enters the interior of the eye
      - Iris
        
        round muscle
        
        the colored part of the eye
        
        can change the size of the pupil, letting more or less light into the eye
        
        helps focus the image; people try to do the same thing by squinting.
        
        BEHIND -> lens
        
        clear structure
        
        The flexible lens finishes the focusing process begun by the cornea
        
        visual accommodation
        
        Process where the lens changes its shape from thick to thin, enabling it to focus on objects that are close or far away
        
        presbyopia
        
        the lens hardens through aging
        
        myopia
        
        visual accommodation may occur but the shape of the eye causes the focal point to fall short of the retina
      - Retina, Rods, and Cones
        
        Rods
        
        are found all over the retina except the fovea, but are concentrated in the periphery.
        
        Fovea
        
        the center of the retina, where cones are densely packed
        
        low levels of light, no color information
        
        are sensitive to changes in brightness but not to a variety of wavelengths, so they see only in black and white and shades of gray
        
        Cones
        
        high levels of light, color information
        
        special receptor cells (photoreceptors) that respond to the various wavelengths of light
        
        Retina
        
        final stop for light within the eye
        
        light-sensitive area at the back of the eye
        
        Photoreceptors (rods and cones)
        
        Bipolar cells
        
        Ganglion cells
        
        Optic nerve
        
        bundle of ganglion cell axons that
        exits the eye at the back of the retina
        
        Carries information from retina to thalamus
        
        Creates the blind spot
        
        Light must travel past ganglion cells and bipolar
        cells to get to photoreceptors
        
        Neural signals travel in opposite direction
        
        Photoreceptors -> Bipolar cells -> Ganglion cells
- - - - height of peaks (Perceived as volume)
    - - number of peaks per second (Perceived as pitch)
  - - - Three tiny bones (ossicles)
        
        Anvil (incus)
        
        connects hammer and stirrup
        
        Stirrup (stapes)
        
        attached to oval window
        
        Hammer (malleus)
        
        attached to eardrum
        
        Ossicles amplify signal from sound waves
    - - Oval window
        
        membrane at the entrance of the inner ear
        
        Vibrates when hit by stirrup
      - Cochlea
        
        snail-shaped structure of the inner ear that is filled with fluid
        
        Basilar membrane
        
        membrane running through middle of cochlea, contains organ of Corti
        
        Organ of Corti - contains receptor cells (hair cells)
      - Auditory nerve
        
        bundle of axons from the hair cells in the inner ear
        
        contains the axons of all the receptor neurons
    - - Auditory canal
        
        short tunnel that runs from the pinna to the eardrum
      - Eardrum
        
        tympanic membrane
        
        Vibrates when hit by soundwaves
      - Pinna
        
        visible part of the ear (Collect sound waves)
        
        serves as a kind of concentrator, funneling the sound waves from the outside into the structure of the ear.
  - - - psychological experience of sound that corresponds to the frequency of the sound waves
      - Higher frequencies -> higher pitches
      - how high or low a sound is
      - Place theory
        
        location of neural (hair cell) firing on organ of Corti determines perceived pitch
        
        Explains perception of moderate/high pitches
      - Frequency theory
        
        states that pitch is related to how fast the basilar membrane vibrates
        
        frequency of neural (hair cell)
        firing determines perceived pitch
        
        Explains perception of lower pitches (< 1,000 Hz)v
- - - - problems with the mechanics of the outer or middle ear and means that sound vibrations cannot be passed from the eardrum to the cochlea.
      - In this kind of impairment the causes can often be treated
    - - the problem lies either in the inner ear or in the auditory pathways and cortical areas of the brain
      - This is the most common type of permanent hearing loss
- - - - tendency to interpret the shape on an object as being constant, even when its shape changes on the retina
    - - tendency to perceive the apparent brightness of an object as the same, even when the light conditions change
    - - tendency to interpret an object as always being the same actual size,regardless of its distance
  - - - tendency to perceive objects,
        or figures, as existing on a background
      - Reversible figures
        
        visual illusions in which the figure and ground can be reversed
    - - tendency to perceive objects that are close to one another as part of the same grouping
      - Group nearby items
    - - tendency to perceive things that look similar as being part of the same group
      - Group similar items
    - - tendency to complete figures that are incomplete
      - Fill in missing parts
    - - tendency to perceive things as simply as possible with a continuous pattern rather than with a complex, broken-up pattern
      - Simple, continuous patterns
    - - Group items in same area
      - tendency is to perceive object by different groups
  - - - Overlap
        
        If one object seems to be blocking another object, people assume that the blocked object is behind the first one and, therefore, farther away.
      - Aerial (atmospheric) perspective
        
        The farther away an object is, the hazier the object will appear to be due to tiny particles of dust, dirt, and other pollutants in the air
      - Relative size
        
        when objects that people expect to be of a certain size appear to be small and are, therefore, assumed to be much farther away
      - Texture gradient
        
        If there are any large expanses of pebbles, rocks, or patterned roads (such as a cobblestone street) nearby, go take a look at them one day.
      - Motion parallax
        
        objects outside the car window seem to zip by very fast when they are close to the car, and objects in the distance, such as mountains, seem to move more slowly
      - Linear perspective
        
        When looking down a long interstate highway, the two sides of the highway appear to merge together in the distance
      - Accommodation
        
        makes use of something that happens inside the eye.
        
        The lens of the human eye is flexible and held in place by a series of muscles
        
        Muscular cue
    - - Convergence
        
        muscular cue
        
        rotation of the two eyes in their sockets to focus on a single object
        
        More convergence for closer objects
        
        Less convergence for distant objects
      - Binocular disparity
        
        the eyes are a few inches apart, they don’t see exactly the same image
        
        Greater disparity for closer objects
        
        Smaller disparity distant objects
- - - - a rapid series of still pictures will appear to be in motion
      - Motion pictures
    - - lights turned on in a sequence appear to move
    - - a small, stationary light in a darkened room will appear to move or drift
      - Because there are no surrounding cues to indicate that the light is not moving