Attentional Processes Gaia Scerif Room 426, Ext Office Hours: Thurs 11-1

Learning Objectives 1.Early development of attention: Describe maturational accounts. 2.Early development of attention: Evidence for and against maturation. 3.Later changes in attentional processing: Qualitative or gradual changes through childhood into adulthood. 4.Can these sources of evidence be integrated? How?

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

Theoretical issues What is “attention”? 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 ) “Attention” is not well understood. So…

Theoretical issues Disadvantages (interesting reading: Walsh, 2003) : Disadvantages (interesting reading: Walsh, 2003) : Too vague a construct to be useful Too vague a construct to be useful Not “localised” to any particular brain circuit (e.g., the parietal lobe) Not “localised” to any particular brain circuit (e.g., the parietal lobe) Mechanisms and computations? 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? Why study “attention”?

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

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) 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) Could changes in attention account for some domain-specific developmental changes? (e.g., number, physics)

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

Findings: The newborn Saccadic pursuit tracking: step-like and lagging behind moving stimuli (Aslin, 1981) 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) 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) Externality effect: focus on external elements of a display (Maurer & Young, 1983) Evidence of early inhibition of return (IoR) (Valenza et al., 1994) Evidence of early inhibition of return (IoR) (Valenza et al., 1994)

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

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

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

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

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

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

Johnson (1990, 2000): Johnson (1990, 2000): Maturation of multiple pathways: 1.Retina to SC: Rapid eye-movements towards easily discriminable stimuli ---> newborn 2.V1 and MT to SC: Driven by moving stimuli ---> onset of smooth pursuit (1-3 mos) 3.BG to SC: Allows tonic inhibition of saccades to peripheral stimuli ---> obligatory attention (1-3 mos) 4.FEF: Detailed analyses of complex visual stimuli; sequencing of eye movements ---> gradual 5.PC: Covert orienting of attention ---> gradual 6.DLPFC: Control in tasks involving delays ---> gradual Early Visual Attention: Accounts

Maturational accounts: Limitations Onset of functioning is not all-or-none: 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 ) 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) Frontal cortices involved in perceptual processing early in development (electrophysiological markers, Csibra et al., 2000) Prediction of sequences, rather than static ages of onset Prediction of sequences, rather than static ages of onset Dynamic interactions across areas are poorly understood Dynamic interactions across areas are poorly understood

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

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

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

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

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

Beyond Infancy: What develops? Qualitative or gradual changes? Qualitative changes in specific processes? Qualitative changes in specific processes? Visual search Visual search FeatureConjunction

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

Beyond Infancy: What develops? Qualitative or gradual changes? Gradual changes in attentional capacity Gradual changes in attentional capacity Long-standing controversy (adults): Is attention limited in capacity? Is attention limited in capacity? Does attentional selection operate early or late during processing? 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 High: early; Low load: late selection

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.)? 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! X N Irrelevant distractor, conflicts with central target identity X Y T O Z R F N

Beyond Infancy: What develops? Gradual changes in attentional capacity Gradual changes in attentional capacity Perceptual load determines the locus of selection through development: Childhood: (Huang-Pollock et al. 2002) 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) Ageing: (Maylor & Lavie, 1998)

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

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

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