Chapter 3 - Slide 1

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Chapter 3 - Slide 1

  1. 1. Cognition Ch. 3 Sensation, Perception and Attention
  2. 2. 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
  3. 3. 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
  4. 4. 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
  5. 5. 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
  6. 6. 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
  7. 7. 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
  8. 8. 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
  9. 9. 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
  10. 10. 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
  11. 11. 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
  12. 12. 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
  13. 13. 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
  14. 14. 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
  15. 15. 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

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