Sensation & Perception

Psychophysics
1. Just Noticeable Difference (JND)
  1. Weber's Law
    1. Size of a JND is a constant proportion of the size of initial stimilus
      1. 1/3 for weight & pain
      2. 1/60 for vision
      3. 1/10 for hearing
    2. Different fractions apply to different types
  2. Fechner's Law
    1. The amount of sensory experience is proportional to # of JND's
      1. Stimilus is above absolute threshold
      2. Same amount of increase in stimilus
        Brings smaller increases in perceived increase
        light
        sound
2. Threshold
  1. The diving point between energy levels
    1. That do & do not have a detectable effect
  2. Absolute Threshold
    1. Input is the minimum amount of stimulation that an organism can detect
      1. Stimulus Intensity
        Increase
        Subjects probability of responding increases
        Detected 50% of the time
    2. Define the boundaries
      1. of an organism's sensory capabilities
3. The study of how physical stimuli are translated into psychological experience
4. Sensory Adaption
  1. Gradual decline in sensitivity due to prolonged stimulation
  2. Pervasive aspect of everyday life
  3. Built-in Process
    1. Sensory Input
      1. Keeps people tuned in to changes
      2. Rather than constants
  4. Ignore the obvious
  5. Focuses on changes
Vision
1. Eye
  1. Lens
    1. Behind the Iris
    2. Transparent eye structure
      1. Focuses light rays
        That fall on the Retina
    3. Made up of soft tissue
      1. Capable of adjustments
        Accomodation
        Occurs when curvature of the lens adjusts to visual focus
        Lens of eye gets fatter
        To give Clearer Image
  2. Pupil
    1. opening in center of Iris
      1. regulate amount of light passing into rear chamber of eye
    2. Constricts
      1. lets LESS light in
      2. sharpens the image
    3. Dilates
      1. lets light in
      2. Image is LESS sharp
    4. Saccades
      1. Constant Motion
        eyes constantly scan environment
        making brief fixations
      2. Essential to good vision
  3. Retina
    1. Neural tissue lining the inside of the back surface of eye
    2. absorbs light, processes images, sends info to brain
    3. Optic Disk
      1. Hole in the retina where optic nerve fibres exit the eye
    4. Cones
      1. Visual receptors
        Key role in daylight vision
        Key role in color vision
      2. Do not respond well
        to dim light
      3. Provide better visual acuity
        sharpness
        precise detail
      4. Fovea
        Tiny spot in Center of Retina
        Contains only cones
        Visual acuity is BEST at this spot
    5. Rods
      1. Visual Receptors
        Key Role
        Night Vision
        Peripheral Vision
    6. Light Adaption
      1. Light
        Less Sensitive
        To Light in High illumination
      2. Dark
        More Sensitive
        To light in LOW illumination
2. Brain
  1. Info. Processing
    1. Receptive Field of a visual cell
      1. Retinal Area
        When stimulated affects the firing of cell
    2. Optic Nerve
      1. Collection of axons
        Connect the eye with the brain
    3. Center-Surround Arrangement
      1. Center being excitatory
      2. Surround inhibitory
        or vice versa
      3. Allows us to see edges clearly
  2. Optic Nerve
    1. Divided
    2. Optic Chasm
      1. Optic Nerve crosses here
        half of each eye
        left side of each eye goes to left brain
        Goes to other side of brain
  3. VISUAL CORTEX
    1. Simple Cells
      1. Respond to
        Certain witdth
        angle
        position
        in receptive field
    2. Complex Cells
      1. any position
      2. Certain Width
      3. Angle
      4. SOME ONLY RESPOND TO A LINE MOVING IN A CERTAIN DIRECTION
    3. CELLS IN THE CORTEX ARE HIGHLY SPECIALIZED
      1. Known as FEATURE DECTECTORS
        Neurons that respond only to specific features
        of more complex stimuli
  4. VISUAL AGNOSIA
    1. inability to recognize objects
  5. PROSOPAGNOSIA
    1. inability to recognize familiar faces
3. Color Vision
  1. Trichromatic Theory
    1. Hermann von Helmholtz (1852)
      1. Human eye has 3 types of receptors
        Differing sensitivities to diff. Light Wavelengths
        Red
        Blue
        Green
        tv works this way
    2. Color Blindness
      1. Occurs more frequently in MALES
      2. Dichromats
        They only see with 2 channels
      3. Lack red, green or blue channel
        rare to not have blue working
      4. SUPPORTS TRICHROMATIC THEORY
      5. Hard to distinguish
        green from red
        yellow from blue
  2. Opponent Process Theory
    1. Complementary Colours
      1. pairs of colours
        produce gray tone when mixed
    2. Afterimage
      1. Image persists after stimulus is removed
      2. Trichromatic Theory CAN'T account for afterimage effect
    3. Ewald Hering (1878)
      1. Color Perception depends on receptors
        Opposite Responses to 3 pairs of colours
        blue/yellow
        red/green
        black/white
        also colors of afterimages
  3. WE NEED BOTH THEORIES TO EXPLAIN COLOR VISION
  4. RETINA HAS 3 TYPES OF CONES
    1. red
    2. blue
    3. green
4. Processing
  1. Top-Down
    1. like reversible figures
    2. when we perceive a word
      1. before we know all the letters
  2. Bottom-Up
    1. Used in feature Analysis
    2. starts at parts and builds towards the whole
Hearing
1. Properties of Sound
  1. Wavelength/Frequency - PITCH
    1. Measured in HERTZ (HZ)
    2. Humans only hear 20-20,000 Hz
      1. usually 2000-4000
  2. Wave Amplitude
    1. quality of loudness
    2. Measured in Decibels (dB)
    3. Painful after 120 dB
  3. Wave purity/mixture
    1. Timbre
      1. Complexity of sound wave
    2. Purest sound has only one frequency of vibration
  4. Auditory Perception they INFLUENCE
    1. Place Theory
      1. Hermann von Helmholtz (1863)
        proposed place theory of pitch
      2. Spiral Cochlea
      3. Basilar Membrane
        Hair Cells
        Auditory Receptors
    2. Frequency Theory
      1. Entire Basilar Membrane
        Vibrates at different frequencies
        Auditory nerve fibres
        fire at different rates
        Letting brain know pitch of sound
  5. George von Bekesy (1947)
    1. sound travels in waves
      1. Peak in a certain place depending on frequency
        Builds on PLACE THEORY
2. How it processes
  1. Basilar Membrane
    1. runs length of cochlea
      1. Hair Cells
        Stimulated by waves of fluid
The Other Senses
1. Taste
  1. Gustatory Receptors
    1. Taste Buds
      1. line the trenches around tiny bumps
        called papillae
  2. FOUR MAIN TASTES
    1. Sweet
      1. Babies like sweet
    2. Sour
    3. Bitter
    4. Salty
  3. Most taste Preferences are learned
  4. SUPER tasters
    1. 4 times as many taste buds
    2. women
    3. DISLIKE
      1. Sweets
      2. Veggies
      3. alcohol
      4. smoking
      5. high fat foods
  5. If a person lacks smell taste will be affected
2. Smell
  1. Receptors
    1. Olfactory Cilia
      1. Hairlike structures
      2. In upper portion of nasal passages
    2. Axons that Synapse with cells
      1. In olfactory bulb
        base of brain
  2. 10,000 different odors
  3. Pheremones
    1. Chemical Messages
    2. Linked to sexual attraction
    3. send from one member of species to another
3. Touch
  1. Sensing Pressure
    1. Nerve Fibres
      1. Carry messages from outside world
        To spinal cord
        To brain stem
        go to opposite side of brain
    2. Signals pass through THALAMUS
      1. To Somatosensory cortex
        Parietal Lobe
4. Pain
  1. Pathways
    1. Fast
      1. Uses myelinated neurons
      2. Registers pain in a second
    2. Slow
      1. Unmyelinated Neurons
      2. Less localized, longer aches
      3. Burning pain comes later
  2. Gate Control Theory
    1. Incoming Pain
      1. passes through process
        in spinal cord
    2. can be closed by skin receptor signals
    3. Can be closed by brain receptor signals
Sensation
1. The stimulation of sense organs
Perception
1. The selection, organization, & interpretation
  1. of Sensory Input

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	Criado por Jessica Auger aproximadamente 9 anos atrás