Perceptual Load
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Perceptual Load

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Perceptual Load Perceptual Load Presentation Transcript

  • Perceptual load as a major determinant of the locus of selection in visual attention Lavie, N.,& Tsal, Y.(1994). Perception & Psychophysics, Vol.56(2), 183-197.
  • Overview
    • Theoretical discussion
      • perceptual load
    • Literature review
      • Early and late selection
    • Conclusion
  • Background
    • Broadbent (1958):
      • Early selection:
        • Limited process
        • Analysis of physical features
  • Background
    • Deutsch and Deutsch’s (1963):
      • Late selection:
        • Unlimited process
        • Parallel
        • Relevant response
  • Background
    • Kahneman and Treisman (1984):
      • Paradigmatic shift
        • Filtering paradigm
          • Shadowing task (Cherry,1953)
          • Partial-report technique (Sperling,1960 )
        • Selective set paradigm
          • Spatial and semantic priming
          • Visual search experiment
  • Some debate about early selection
    • Broadbent’s filter model – limited capacity channel
    • Physical distinction rather than info load
    • Clear physical distinction of relevant info is insufficient for early selection
    • Lavie:
      • Physical distinction->priority->cannot prevent irrelevant info processing
      • Perceptual load of relevant info
      • prevent irrelevant processing
  • The proposed model for selective attention
    • Lavie’s premise:
      • Limited capacity :
        • early selection
        • late selection (automatic process)
  • Literature review
    • Structural approach
    • Perceptual load
    • Physical distinctiveness between relevant and irrelevant items
  • Literature review
    • Qualitative
      • Unlimited perception when one irrelevant stimulus is processed
    • Quantitative
    • Limited perception but at the same time can accommodate more than one item
    • early selection =high perceptual load
    • Late selection = low perceptual load
  • Perceptual load Operational definition
    • No. of units/items in the display
      • Ex. A string of letters
      • word = 1 unit
      • letters = many units
    • Nature of processing for each unit
  • Physical distinctiveness
    • Major factor in determining nature of selection
    • Focus on location
    • Low load – poor distinction / clear distinction between target and distractor
  • Low perceptual load + poor physical distinction
    • Poor distinction:
      • relevant and irrelevant stimuli occupy the same location
      • Ex. Stroop task
      • Parallel processing of relevant and irrelevant dimensions
      • Asymmetric interference. ex.: word -> color
  • Low perceptual load + poor physical distinction
      • Logan (1980): manipulate expectancy
      • Eriksens (1974):
        • AUA AAUAA
        • irrelevant distractor is identified
  •  
  •  
  •  
  • Low perceptual load + poor physical distinction
      • Eriksens and Schultz (1979):
        • Prolong the process of target-> increase distractor effect
  • Low perceptual load + poor physical distinction
      • Miller (1987):
      • Flank X target appear left
      • Flank O target appear right
        • High correclation:88valid cue
        • 8invalid cue
        • Low correclation:56valid cue
        • 40invalid cue
  • Low perceptual load + poor physical distinction
  •  
  • Low perceptual load + poor physical distinction
      • Lavie:
        • Low load-> spare attentional capacity-> irrelevant stimuli
  • Low perceptual load + poor physical distinction
      • Paquet and Lortie (1990):
        • “ +” attenuates associated-flanker effect
        • Spatial precue reduced distractor effect but not eliminated it
  • Low perceptual load + clear physical distinction
    • Eriksen (1974):
      • Contour-to-contour distance
    • Keren, O’Hara, and Skelton (1977):
      • Same-different matching task
      • Flanking targets
  •  
  •  
    • Tipper (1985):
      • Negative priming (NP)
      • Same identity, different shape(letter) -> NP still occurred
    • Tipper & Cranston (1985):
      • Pictures and names -> NP still occurred
    • Distractor was processed to the semantic level
    • low load-> clear distinction-> irrelevant processing
  •  
    • Merikle and Gorewich (1979):
      • Size, distance-> incompatible distractor-> interfere
    • Hagenaar and van der Heijden (1986):
      • Color patch-> compatibility
  • Manipulating display size Studies with high perceptual load
  • Manipulating display size
    • Clearer evidence that early selection is found only under conditions of high perceptual load
    • Navon (1989)
    • “ possibility of early selection among all possible combinations of”
      • physical properties {color , size}
      • Semantic property {relevant item: letter / digit}
  • Items : letters + digits
    • Low load display
      • 2 item
    • High load display
      • 4 item
      • Distractor could be compatible / incompatible
    1 Target ` 1 Distractor 1 Target ` 3 Distractors
  • Results
    • Color = no effect of display size nor of distractor compatibility
    • Category =display size interacted with distractor compatibility effect
  • 2- item 4-item
    • responses when the distractor was incompatible than when it was neutral or compatible
    • Late selection
    • No effect on distractor compatibility
    • Distractor interference was reduced when the load was relatively high
    • Thus early selection
    • 2. Kahneman and Chajczyk (1983)
    • “ manipulated perceptual load in a variation of the stroop task”
    • RT for naming color of a central patch appearing together with a black word directly above or below it.
  •  
  • Experiment .
  •  
  • Results
    • Word spelt a compatible color naming responses were faster
    • Compatibility effect was reduced when: 1. second neutral word
    • 2. array of Xs was added
    • Reduction of attn. resources by neutral stimulus to capture incompatible distracting stimulus
    • “ Attn. resources are involuntarily allocated to irrelevant stimuli only when relevant processing is not sufficiently demanding.”
  • Possible extensions to other modalities (auditory)
    • Zelinker (1971)
    • Shadow list of digits (4)
    • Ignore feedback of their voices (0.2s delay)
    • 3 groups of shadowing
  • Results
    • Easy shadowing
    • Difficult shadowing
    • Resources interference
    Delayed feedback difficult to ignore More stuttering Reduced interference
    • Barr and Kapadnis (1986)
    • ” manipulating difficulty of the relevant task affects the ability to ignore an irrelevant auditory message ”
    • Standard shadowing test (English)
    • Native speakers and non native speakers
  • Results
    • Native speakers noticed more changes in unattended channel
    • Ex. Speech interruptions
    • reduction in voice intensity
    • Changes caused more interferences in shadowing
    • Non-native speakers resources
    • processing of irrelevant message
  • Summary
    • Early or late selection is determined by:
    • 1) perceptual load
    • 2)physical distinctiveness.
    • Early selection :
      • desirable perceptual loads ↑
      • possible when there is a clear distinction between relevant and irrelevant items