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    Sensation outline Sensation outline Presentation Transcript

    • Unit 4. Sensation and Perception College Board - “Acorn Book” Course Description 6-8% (7-9% in past) Unit IV. Sensation and Perception
    •  
    •  
    • Overview
      • A. Thresholds
      • B. Sensory Mechanisms
      • C. Attention
      • D. Perceptual Processes
      Unit IV. Sensation and Perception
    • Unit IV. Sensation and Perception
    • A. Thresholds
      • Threshold
      • Absolute threshold
      • Just-noticeable-difference (jnd)
      • Weber ’s Law
      • Fechner ’s Law (Psychophysical scaling)
      • Subliminal perception
      Unit IV. Sensation and Perception
    • Signal Detection Theory Chart Unit IV. Sensation and Perception Response Yes Response No Signal Present Signal Absent
    • Signal Detection Theory Correctly identifies stimulus present Unit IV. Sensation and Perception Response Yes Response No Signal Present HIT Signal Absent
    • Signal Detection Theory Fails to identify stimulus present Unit IV. Sensation and Perception Response Yes Response No Signal Present Hit MISS Signal Absent
    • Signal Detection Theory Incorrectly identifies stimulus as present when absent Unit IV. Sensation and Perception Response Yes Response No Signal Present Hit Miss Signal Absent FALSE ALARM
    • Signal Detection Theory Correctly identifies stimulus as absent Unit IV. Sensation and Perception Response Yes Response No Signal Present Hit Miss Signal Absent False Alarm Correct Negative
    • B. Sensory Mechanisms
      • Vision
      • The Stimulus – Light
        • Amplitude, wavelength, purity, saturation
      • Structure of the Eye
        • Lens, retina, rods & cones, fovea
        • Bipolar cells and ganglion cells
        • Optic nerve and blind spot
      Unit IV. Sensation and Perception
    • Figure 6.7 The eye Myers: Psychology, Ninth Edition Copyright © 2010 by Worth Publishers
    • Figure 6.8 The retina ’s reaction to light Myers: Psychology, Ninth Edition Copyright © 2010 by Worth Publishers
    • Table 6.1 Myers: Psychology, Ninth Edition Copyright © 2010 by Worth Publishers
    • Color - Color - Color
      • Chromatic vs. achromatic (Colors vs. black & white)
      • Hue, brightness, saturation (Color, light-dark, purity of color)
      • Subtractive mixture vs. additive mixture (filters vs. paints)
      • Good Web Site on Color Mixing
        • http:// home.att.net /~RTRUSCIO/COLORSYS.htm
      Unit IV. Sensation and Perception
    • Additive
      • New colors are made by the combination of different colored lights
      • The three colors used are Red, Green, and Blue
      • This is used for television screens, video, and computer monitors
      Unit IV. Sensation and Perception
    • Source: http://en.wikipedia.org/wiki/Color_mixing
      • A simulated example of additive color mixing
      Unit IV. Sensation and Perception
    • Subtractive
      • New colors can be made when paints, inks, markers, and other coloring media are combined
      • The three colors used are Magenta, Yellow, and Cyan
      • This is used in color printers
      Unit IV. Sensation and Perception
    • Source: http://en.wikipedia.org/wiki/Color_mixing
      • A simulated example of subtractive color mixing
      Unit IV. Sensation and Perception
    • http://home.att.net/~RTRUSCIO/COLORSYS.htm
      • The above site provides an informative explanation and description of color mixing
        • Color Vision
        • Mixing Light
        • Mixing Dyes – Paints – Ink
        • The Basic Three - The physics and biology of color mixing
        • Painting
        • Photography
        • Printing
        • Other Considerations
      Unit IV. Sensation and Perception
    • Color Vision
      • Trichromatic theory –
      • Young-Helmholtz (three color receptors – different wavelengths)
        • Color blindness (dichromats, etc.)
        • Processing at receptor level
      • Opponent-process theory –
      • Hering, Jameson, Hurvich (three pairs of color-sensitive neurons)
        • Negative afterimage
        • Processing at receptive field level (thalamus)
      Unit IV. Sensation and Perception
    • Color Vision: From Weiten. Themes and Variations . 4 th ed. Brooks/Cole. 1998 Unit IV. Sensation and Perception
    • Colors of the Rainbow
      • R O Y G B I V
      • Color is determined by wave length
      • Red is the longest wavelength of visible light. Violet is the shortest
      • Water (mist) refracts light into different wavelengths
      Unit IV. Sensation and Perception
    • Hearing
      • The Stimulus – Sound waves
        • Amplitude (Loudness), Wavelength or frequency (Pitch), Wave purity or mixture (Timbre))
      • Structure of the Ear
        • Outer ear – Auditory canal
        • Middle ear – Eardrum, Hammer, Anvil, Stirrup
        • Inner ear – Cochlea, Basilar Membrane
      Unit IV. Sensation and Perception
    • The Ear From Coren, Ward, & Enns. Sensation and Perception 6 th ed. John Wiley & Sons, Inc. 2004
      • Outer Ear
      • Auditory Canal
      • Eardrum
      • Middle Ear
      • Hammer, anvil, stirrup
      • Inner Ear
      • Cochlea
      Unit IV. Sensation and Perception
    • The Inner Ear From Coren, Ward, & Enns Sensation and Perception 6 th ed. John Wiley & Sons, Inc. 2004 Unit IV. Sensation and Perception
    • Figure 6.16 Hear here: How we transform sound waves into nerve impulses that our brain interprets Myers: Psychology, Ninth Edition Copyright © 2010 by Worth Publishers
    • Taste and Smell
      • Taste (Gustatory Sense)
        • Stimulus – Chemicals
        • Four taste receptors
      • Smell (Olfactory Sense)
        • Stimulus – Chemicals
        • Olfactory bulbs, olfactory cilia
        • Pheromones
        • Taste and Smell
      • Demonstrations
      • Raw Apple, Raw Potato, Raw Onion
      • Jelly Bellies
      Unit IV. Sensation and Perception
    • Skin Senses
      • Pressure
      • Hot
      • Cold
      • Pain
        • Gate control theory in pain perception
      Unit IV. Sensation and Perception
    • See Reading: WHAT IS PAIN?
      • Messages about tissue damage are picked up by nociceptors and transmitted to the spinal cord via small myelinated fibers and very small un-myelinated fibers.
      • From the spinal cord, the impulses are carried to the brainstem, thalamus and cerebral cortex, and ultimately perceived as pain.
      • These messages are suppressed by a system of neurons that originate in the gray matter of the midbrain.
      Unit IV. Sensation and Perception
    • Unit IV. Sensation and Perception
      • This descending pathway sends messages to the spinal cord where it suppresses the transmission of tissue-damage signals to the higher brain centers.
      • Some of these descending pathways utilize naturally-occurring chemicals called opioids.
      Unit IV. Sensation and Perception
    • Unit IV. Sensation and Perception
    • HOW PAIN KILLERS WORK.
      • At the site of injury, the body produces prostaglandins which increase pain sensitivity.
      • Some analgesics, such as aspirin, prevent the production of prostaglandins.
      • Acetaminophen is believed to block pain impulses in the brain itself.
      • Local anesthetics intercept pain signals traveling up the nerve.
      • Opiate drugs prevent the transfer of pain signals from the spinal cord to the brain.
      Unit IV. Sensation and Perception
    • Unit IV. Sensation and Perception
    • Internal Senses
      • Kinesthesis
        • Internal body position
        • Muscle position
      • Vestibular sense
        • Balance
        • Semi-circular canals in ear
      Unit IV. Sensation and Perception
    • C. Sensory Adaptation
      • Sensory adaptation is a change in sensitivity to a stimulus that results from exposure to the stimulus.
      • Examples include adapting to darkness, adapting to bright conditions, adapting to hot or cold conditions, adapting to the presence of odors, and many more.
      Unit IV. Sensation and Perception
    • Sensory Adaptation
      • Light and Dark Adaptation
        • Entering / Exiting a movie theatre
        • One eye covered demonstration
      • The eye has two types of photoreceptors
        • Cones (for color)
        • Rods (for night vision)
      Unit IV. Sensation and Perception
    • Dark Adaptation
      • Move into a darkened theater and two changes occur to increase sensitivity to light:
        • The pupils enlarge. This admits more light onto the retina of the eye.
        • Light-sensitive chemicals in the photoreceptors increase their concentration. This makes each photoreceptor more sensitive to light .
      Unit IV. Sensation and Perception
    • Light Adaptation
      • Leaving the theater, you encounter bright light
        • Your pupils constrict immediately, reducing the light reaching the retina
        • The light-sensitive chemicals in the photoreceptors quickly bleach out, reducing the photoreceptors ’ sensitivity to light
      Unit IV. Sensation and Perception
    • Preserving Dark Adaptation
      • It takes 20-30 minutes to become fully dark adapted
      • This is destroyed by exposure to light in a few seconds
      • Rods are blind to red light
        • Cover light source with red lens
          • Read map with cones
          • Rods remain dark adapted
      Unit IV. Sensation and Perception
    • Sound Adaptation
      • Adaptation to loud noise
      • Very loud sound
        • small muscle in the inner ear contracts
        • dampens sound vibrations being conducted by the ossicles (bones) to the chochlea
      • Adaptation does not work well for sudden loud sounds, such as gun shots
      Unit IV. Sensation and Perception
    • Odor / Smell
      • The sense of smell is probably the quickest sense - as a whole - to adapt
      • We can detect amazingly low concentrations of some chemicals in the air (e.g., perfumes) but although the perfume is still in the air about us, we quickly cease to detect it
      Unit IV. Sensation and Perception
    • Taste
      • Certain tastes may cause rather surprising (and unexpected) anomalies in other taste stimuli
        • Eating artichoke makes sour substances taste sweet briefly
        • Jujuba temporarily abolishes sweet sensitivity
      • Spicy foods will also stimulate pain receptors
      Unit IV. Sensation and Perception
    • Touch – Heat – Cold
      • Skin temperature receptors respond more to rate of change in temperature than to steady temperature
      • This explains why hot bath feels hot at first, then cooler
      • This explains why pool/ocean feels freezing at first, then comfortable cool
      • Demonstration
        • One Hand in Cold Water, the other in Warm Water
      Unit IV. Sensation and Perception
    • Pain Adaptation
      • Acute pain – tells us to get away from the painful stimulus
      • Chronic pain – tells us not to move something while it heals
      Unit IV. Sensation and Perception
    •  
    • C. Attention
      • Selective Attention
      • Bottleneck Theories of Selective Attention
        • We have a limited capacity to attend to stimuli
        • There is no limit to how much stimulation can be present
      • Selective Attention allows us to select what to attend to
        • Sometimes we seem to do it
        • Other times it seems to happen to us
      Unit IV. Sensation and Perception
    • Selective Attention and the Cocktail Party Phenomenon
      • Cocktail Party Phenomenon
        • the ability to focus one's listening attention on a single talker among a mixture of conversations and background noises, ignoring other conversations
        • then if someone over the other side of the party room calls out our name suddenly, we also notice that sound and respond to it immediately
      Unit IV. Sensation and Perception
    • Selective Attention and the Stroop Test
      • Stroop Test
        • Why is this task so difficult to do
        • reading is an automatic process
        • color naming is a controlled process
        • automatic process of reading interferes with our ability to selectively attend to ink color
      Unit IV. Sensation and Perception
    • Bottleneck or Filter Models of Selective Attention
      • Early selection
      • David Broadbent (1958) proposed that physical characteristics of messages are used to select one message for further processing and all others are lost
      • Attenuation
      • Treisman (1964) proposed that physical characteristics are used to select one message for full processing and other messages are given partial processing
      • Late Selection
      • Deutsch & Deutsch (1963) proposed that all messages get through, but that only one response can be mad
      Unit IV. Sensation and Perception
    • D. Perceptual Processes
      • Feature analysis
      • Bottom-up processing
      • Top-down processing
      Unit IV. Sensation and Perception
    • Is it a circus act?
      • Or a couple dancing?
      • Ambiguous or Reversible figure
      • Feature analysis
        • Detecting specific elements
        • Assembling them in a more complex form
      Unit IV. Sensation and Perception
    • Bottom-up Processing
      • A progression from
        • Individual elements to the whole
      • Also called data-driven processing
      Unit IV. Sensation and Perception Detect Specific Features Combine features Recognize Stimulus
    • Bottom-Up Processing
      • Perception must be largely data-driven because it must accurately reflect events in the outside world
      • The information is determined mainly be information from the senses (not from your expectations)
      Unit IV. Sensation and Perception
    • Top-Down Processing
      • A progression from
        • The whole to the elements
      • Also known as schema-driven processing
      Unit IV. Sensation and Perception Form perceptual hypothesis about the nature of the stimulus as a whole Select and examine features to Check hypothesis Recognize Stimulus
    • Top-Down Processing
      • In many situations your knowledge or expectations (or schemas) will influence your perception
      • In this case a schema is a pattern formed earlier in your experiences.
      Unit IV. Sensation and Perception
      • Abstract concepts tend to be referred to as higher level
      • Concrete details are referred to as lower level
      • Top-down occurs when a higher level concept influences your interpretation of lower level data
      • Set or expectancy demonstrate top-down processing
      • Ambiguous figures often demonstrate top-down processing
      Unit IV. Sensation and Perception
      • Visual Contrast
      • Brightness contrast (gray on white appears darker than gray on black)
      • Mach Bands (Series of bands of increasing darkness - each strip affected by the neighboring strips)
      • Lateral inhibition
      Unit IV. Sensation and Perception
    • Brightness Contrast Unit IV. Sensation and Perception
    • Principles of Perceptual Organization:
      • Figure-Ground
      • Grouping (Gestalt Principles)
        • Proximity (Nearness)
        • Similarity
        • Continuity
        • Closure
      Unit IV. Sensation and Perception
    • Closure Unit IV. Sensation and Perception
      • Perception of Depth and Distance
      • Perception of Motion
      • Perceptual Constancy (Size, Shape, Brightness)
      • Perceptual Illusions
      • Perceptual Set
      • Perceptual Adaptation
      Unit IV. Sensation and Perception
    • Depth Perception
      • “ I could have sworn that mesa was a whole lot farther away”
    • Unit IV. Sensation and Perception
    • Necker cube (1) Unit IV. Sensation and Perception
    • Necker cube (2) Unit IV. Sensation and Perception
    • Necker cube (3) Unit IV. Sensation and Perception
    • Necker cube (4) Unit IV. Sensation and Perception
    • Necker cube (5) Unit IV. Sensation and Perception
    • Handouts
      • DISTRIBUTION OF RODS AND CONES – Bernstein (Colored pencils)
      • Light-Dark Sensory Adaptation Demonstration (Eye patch)
      • Simple Compelling Demonstrations of Retinal Disparity ( “Hole in hand” etc.)
      • DEMONSTRATING THAT SMELL IS AS IMPORTANT – Beins (Jelly Bellies)
      Unit IV. Sensation and Perception
      • Monocular Depth Perception Student Assignment
      • Chart - Depth Perception Cues (Study Guide / May be used in a variety of assignments)
      • Color Vision – Roygbiv (Demonstration)
      • Pulfrich effect (Reading from Wikipedia)
      Unit IV. Sensation and Perception
      • Moon Illusion (Reading from Bad Astronomy by Philip Plait)
      • The Big Picture - Gestalt applied
      • The Neuroscience of Yorick's Ghost and Other Afterimages
      • Mindsights Tables (Drawing by Shepard)
      • Various Visual Illusions
      Unit IV. Sensation and Perception
    • The Janus Mask
    • Example of the Ames Room Unit IV. Sensation and Perception
    • The Magic of the Wundt-Jastrow Illusion
    • From: Gregory, R. I., Eye and Brain (2 nd ed.) New York: World University Library, 1973. (pp. 78-80.)