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Chapter 3 - Slide 1

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    Chapter 3 - Slide 1 Chapter 3 - Slide 1 Presentation Transcript

    • Cognition Ch. 3
      Sensation, Perception and Attention
    • Modeling the Perceptual System
      Our brains must convert physical energy to internal coding
      This broad processes involves subprocesses:
      The ability to perceive and store information
      The ability to translate that information into code
      The ability to derive meaning and utility from that code
      The ability to reproduce the original information
      Cognition 4309 Fall 2009
      2
    • Sensation to Perception
      Sensation involves the detection of physical energy
      Perception involves higher-order cognition that “organizes” this energy
      Be careful not to draw too solid a boundary between the two…
      Cognition 4309 Fall 2009
      3
    • Vision - Structure
      Retinal stimulation creates a chain reaction
      Rods and cones, ganglion cells
      Lateral geniculate nucleus (LGN)
      Visual cortex
      The image is “disassembled” into its component parts (features)
      Reconstructed with interpretations installed
      Cognition 4309 Fall 2009
      4
    • The Marriage of Sensation and Perception
      Illusions are good examples of this dynamic
      Examples
      Muller-Lyer
      Figure-ground
      Perceptual sets
      Signal detection
      Cognition 4309 Fall 2009
      5
    • From “Out There” to “In Here”
      Perceptual span – how much we can experience at a brief exposure
      Utilizes a sensory store to hold this information, but only briefly
      Early studies  4-5 letters was capacity, based on brief presentation followed by oral reports
      Early studies built foundation for “box” models of cognition
      Cognition 4309 Fall 2009
      6
    • Iconic Storage
      Sperling what if some data is lost from the iconic store while the participant is reporting other data?
      50 ms presentation of letter lists (3x3 matrix)
      Immediately following – one of three tones linked to rows
      The letters were recalled at close to 100% accuracy
      Caveat  tone delay reduced recall
      Cognition 4309 Fall 2009
      7
    • Memory for Sounds
      Moray et al (1965)
      Four speakers presenting messages simultaneously
      Letter strings presented through 2-4 channels
      Lights were used as cues for recall
      Darwin et al (1972)
      Auditory analog to the Sperling studies
      Left ear, right ear, both ears – visual cue (stimulus position on screen)
      Cognition 4309 Fall 2009
      8
    • Attention
      The concentration of mental effort on sensory or mental events
      Five major aspects
      Processing capacity/selective attention
      Levels of arousal
      Attention control
      Consciousness
      Cognitive neuroscience
      Cognition 4309 Fall 2009
      9
    • Capacity and Selective Attention
      Capacity – ability of the cognitive architecture to handle incoming data
      Attention – concentration of cognitive energy on specific aspects of the environment
      Attention is selective some stimuli are chosen, others are ignored
      The “bottleneck” metaphor
      Cognition 4309 Fall 2009
      10
    • Experimental Evidence
      Cherry (1953, 1966) – shadowing technique
      Moray (1959) – cocktail party effects
      Lessons about selection
      We prefer single streams of data
      Some unattended information may “leak” through
      Repeating information as presented may not translate into encoding that information
      Cognition 4309 Fall 2009
      11
    • Modeling Selective Attention
      Broadbent (1958) – filter theory (Fig 3.10) -- capacity restricted by cognitive architecture
      Data enters a short term store
      A selective filter attends to the data based on its features
      Data moves through channel to begin a closed-loop control function
      Moderated by past probabilities
      Cognition 4309 Fall 2009
      12
    • Modeling Selective Attention
      Treisman (1964) – attenuation model – attention is a function of activation thresholds
      All data is sent to the attentional channel
      Filtered not by characteristics but by perceived importance
      Filter reduces S/N ratio to produce the conscious realization of inattention
      Cognition 4309 Fall 2009
      13
    • Visual Attention
      Serial v. parallel visual search (Treisman, 1988)
      Initial preattentive process that detects basic features of the environment
      Late v. early filter theories
      Late filter or rapid trace decay?
      Cognition 4309 Fall 2009
      14
    • Automatic Processing
      With practice, behaviors require less effortful attention to be produced
      Considerable practice is required – some say 10 years or more
      Three characteristics
      Occurs without intention
      “Concealed” from consciousness
      Consumes few cognitive resources
      Cognition 4309 Fall 2009
      15