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Attentional Processes

Attentional Processes. Gaia Scerif Room 426, Ext. 67926 gs@psychology.nottingham.ac.uk Office Hours: Thurs 11-1. Learning Objectives. Early development of attention: Describe maturational accounts. Early development of attention: Evidence for and against maturation.

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Attentional Processes

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  1. Attentional Processes Gaia Scerif Room 426, Ext. 67926 gs@psychology.nottingham.ac.uk Office Hours: Thurs 11-1

  2. Learning Objectives • Early development of attention: Describe maturational accounts. • Early development of attention: Evidence for and against maturation. • Later changes in attentional processing: Qualitative or gradual changes through childhood into adulthood. • Can these sources of evidence be integrated? How?

  3. Outline • Theoretical issues • The early development of selective attention: • Succession of stages, maturation of neural pathways • Alternatives? • Later development: • Qualitative or Gradual changes? • Group exercise: Conclusions

  4. “Attention” is not well understood. So… Theoretical issues • What is “attention”? “Every one knows what attention is. It is the taking possession by the mind, in clear and vivid form, of one out of what seem several simultaneously possible objects or trains of thought. […] It implies withdrawal from some things in order to deal effectively with others.” (James, 1890/1950, pp. 404-5)

  5. Disadvantages (interesting reading: Walsh, 2003): Too vague a construct to be useful Not “localised” to any particular brain circuit (e.g., the parietal lobe) Mechanisms and computations? Advantages: Not so vague: multiple varieties of “attention”, (Parasuraman, 1998) Distinct processes involve different, potentially interacting circuits (Posner & Petersen, 1990; Johnson, 2001) Useful computational models (Braun et al. 2001) Source of developmental change? Theoretical issues Why study “attention”?

  6. Theoretical issues Why study attentional development? 1. As a “case study” in development: • Does attention develop through stages? • Are changes in attentional performance better accounted for by quantitative vs. qualitative mechanisms?

  7. Theoretical issues Why study attentional development? 2. As (one) source of developmental change across domains: • Attention influences experience of multiple types (e.g., vision, audition) • Could changes in attention account for some domain-specific developmental changes? (e.g., number, physics)

  8. Early Visual Attention: Methods • Changes in looking time as a measure of attentional effects: Video demonstration

  9. Findings: The newborn • Saccadic pursuit tracking: step-like and lagging behind moving stimuli (Aslin, 1981) • Preferential orienting to the temporal field under monocular viewing conditions (Braddick et al., 1992) • Externality effect: focus on external elements of a display (Maurer & Young, 1983) • Evidence of early inhibition of return (IoR) (Valenza et al., 1994)

  10. Central Stimulus Peripheral Stimulus + = Findings: 1 to 3-month-olds • Onset of smooth pursuit tracking (Aslin, 1981) • Increased sensitivity to nasally presented stimuli • Obligatory attention (“sticky” fixation): slower in disengaging from a central stimuli (Stechler & Latz, 1966; Hood & Atkinson, 1993)

  11. 1 Time 2 OR Findings: 3 to 4-month-olds • Anticipatory saccades (Haith et al., 1988; Wentworth & Haith, 1998) • Inhibition of automatic saccades (Johnson, 1995) Infants decrease looking towards the cue only in 1.

  12. Findings: Through the 1st year Gradual improvements: • Faster facilitation towards peripherally-cued locations (Johnson & Tucker, 1996) • Using central cues to direct attention (Johnson et al., 1991) • Ability to delay orienting towards locations (Gilmore & Johnson, 1995)

  13. Early Visual Attention: Accounts Successive maturation of attentional processes and of inputs to related neural systems: • Bronson (1974): • Exogenous vs. endogenous processes • Subcortical vs. cortical mechanisms • Atkinson (1984, 2000): • Exogenous vs. endogenous processes • Subcortical and cortical mechanisms for 1. eye and head movement; 2. reaching and grasping

  14. FEF PC 4 DLPFC 5 6 BG V1 MT 3 2 SC 1 Early Visual Attention: Accounts • Johnson (1990, 2000): Maturation of multiple pathways and areas: • Retina to superior colliculus (SC) • V1 and Middle Temporal area to SC • Basal ganglia to SC • Frontal eye-fields • Parietal cortex • Dorsolateral prefrontal cortex Retina

  15. Early Visual Attention: Accounts • Johnson (1990, 2000): Precise sequence of behaviours driven by the maturational status of V1: • Not mature at birth (Pathway 1 wins over others) • Inside-out pattern of maturation and lower layers project more strongly to MT (Pathway 2 wins over 4, 5, 6) • Frontal projections are slowest to mature (Pathway 3 only gradually controlled by 4, 5)

  16. Early Visual Attention: Accounts • Johnson (1990, 2000): Maturation of multiple pathways: • Retina to SC: Rapid eye-movements towards easily discriminable stimuli ---> newborn • V1 and MT to SC: Driven by moving stimuli ---> onset of smooth pursuit (1-3 mos) • BG to SC: Allows tonic inhibition of saccades to peripheral stimuli ---> obligatory attention (1-3 mos) • FEF: Detailed analyses of complex visual stimuli; sequencing of eye movements ---> gradual • PC: Covert orienting of attention ---> gradual • DLPFC: Control in tasks involving delays ---> gradual

  17. Maturational accounts: Limitations • Onset of functioning is not all-or-none: • E.g., evidence of cortical processing in newborns (pattern recognition, orientation discrimination, e.g. reviewed in Atkinson, 2000) • Frontal cortices involved in perceptual processing early in development (electrophysiological markers, Csibra et al., 2000) • Prediction of sequences, rather than static ages of onset • Dynamic interactions across areas are poorly understood

  18. 1. 2. Maturational accounts: Alternatives Views of Functional Brain Development: • Interactive specialisation • Underlying face and eye-gaze direction processing (Halit et al., 2003; Farroni et al., 2002) • Development as expertise acquisition • Areas involved in skill learning (Csibra et al., 2000)

  19. Accounts: Summary of Evidence Body of evidence: Successive maturation of attentional processes and of inputs to related neural systems However: Dynamic interactions across pathways are poorly understood Growing alternatives to maturational accounts

  20. ? Valid Invalid Beyond Infancy: What develops? Qualitative or gradual changes? • Qualitative changes in specific processes? • Orienting of attention

  21. Peripheral Cues Central Cues Beyond Infancy: What develops? Qualitative or gradual changes? • Qualitative changes in specific processes? • Orienting of attention(Brodeur & Enns, 1997)

  22. Beyond Infancy: What develops? Qualitative or gradual changes? • Qualitative changes in specific processes? • Enumeration(Trick et al., 1996)

  23. Feature Conjunction Beyond Infancy: What develops? Qualitative or gradual changes? • Qualitative changes in specific processes? • Visual search

  24. Beyond Infancy: What develops? Qualitative or gradual changes? • Qualitative changes in specific processes? • Visual search (Trick & Enns, 1998)

  25. Beyond Infancy: What develops? Qualitative or gradual changes? • Gradual changes in attentional capacity Long-standing controversy (adults): • Is attention limited in capacity? • Does attentional selection operate early or late during processing? Perceptual load determines the locus of selection (Lavie, 1995, 2000): • High: early; Low load: late selection

  26. Beyond Infancy: What develops? Qualitative or gradual changes? Perceptual load determines the locus of selection (Lavie, 1995, 2000): • The task: Are “X” or “N” present in the centre (ignore peripheral irrelevant stim.)? Low load: high interference from distractor that conflicts with target High load: lower interference! N N Y Irrelevant distractor, conflicts with central target identity X T X Z F O R

  27. Beyond Infancy: What develops? • Gradual changes in attentional capacity Perceptual load determines the locus of selection through development: • Childhood: (Huang-Pollock et al. 2002) Children's performance was as efficient as adults' under conditions of high but not low loads: early selection engages rapidly maturing neural systems and late selection engages later-maturing systems? • Ageing: (Maylor & Lavie, 1998)

  28. Beyond Infancy: Summary Attentional capacity varies, but there are also more specific changes occurring, suggesting both: • Qualitative changes in specific processes • Changes in attentional capacity Not mutually exclusive mechanisms of change

  29. Group exercise: Conclusions Divide into groups: Researchers investigating infant vs. later attention • Can different sources of information be integrated? • How can each group inform the other? • Methods? • Experimental questions? • Limitations? • Future directions?

  30. Tasks for next week Gaia • Make the points raised in the conclusions available online C8CCDE students: • Read and evaluate: Wynn, K. (1992). Addition and subtraction by human infants. Nature, 358, 749-750. Cohen, L. B. & Marks, K. S. (2002). How infants process addition and subtraction events. Developmental Science, 5, 186-201.

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