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Attention. Part 2. Early Selection Model (Broadbent, 1958). FILTER. input. detection. recognition. Only information that passed the filter received further analysis (e.g. meaning). Late Selection Theory (Deutsch & Deutsch, Norman). FILTER. input. detection. recognition.

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  1. Attention • Part 2

  2. Early Selection Model(Broadbent, 1958) FILTER input detection recognition Only information that passed the filter received further analysis (e.g. meaning).

  3. Late Selection Theory (Deutsch & Deutsch, Norman) FILTER input detection recognition

  4. Early Attenuation Model(Treisman) FILTER input detection recognition

  5. Lab: Feature Search Parallel processing of simple visual features (e.g., color).

  6. “No” “Yes” TypicalResults for “Feature Search” Reaction Time (msec) 6 10 20 30 # of items in display

  7. Conjunction Search • Combination of features (e.g., red AND horizontal) • Spatial arrangements of features (e.g. black above white) When targets are defined by:

  8. Lab: Conjunction Search ‘Find the blue square’

  9. Lab: Conjunction Search

  10. “No” “Yes” Treisman’sResults for “Conjunction Search” Reaction Time (msec) 2 4 6 10 20 30 # of items in display

  11. Neutral Trials 15% Lab: Voluntary Cueing Valid Trials 70% Invalid Trials 15%

  12. Voluntary Cueing • Same result for short and long cue-to-target delays(short ‘green’, long ‘blue’)

  13. + Miscued Trials Neutral Trials + Lab: Automatic Cueing Cued Trials ??% +

  14. + + Automatic Cueing • For short cue-to-target delay (‘green’), same result as for voluntary cueing (validly cued faster than invalidly cued) • For long cue-target delays, the reverse pattern (inhibition of return)

  15. Neurological Deficits in Visuo-spatial attention • Hemi-spatial Neglect • lesion in right temporo-parietal junction • Inability to • attend to the left side of visual space, and thus to • be aware of visual stimulus in the left visual field • Represent spatial relations.

  16. Line-bisection task

  17. LVF RVF Left Right

  18. LVF RVF Left hemisphere Right hemisphere

  19. To study the neural substrate of visuo-Spatial Attention, we need • A patient group: • Hemispatial neglect • A simple method: • Spatial Cueing • A cognitive theory: • Posner’s three stage model

  20. Disengage: • stop attending to what is currently being attended • Move: • refocus spotlight on new location • Engage: • begin attending to new stimulus

  21. + Miscued Trials Spatial Cueing Cued Trials +

  22. Retina LGN V1 Which part of the brain is the source of attention? Where does attention have its effects? (Relay Station) (Detects Edges) (Color, Form) V4 Parietal Cortex (Location, How to reach or act upon) (Shape, Object Recognition) Inferotemporal Cortex

  23. Memory/Attention Task (fMRI / ERP) time

  24. Regions of Interest LVF RVF

  25. Single-Unit Recording Receptive Field (Macaque monkey) “spike” = single neuron’s action potential Signal Analysis Stim 1 Stim 2

  26. Attention Effects in Single Neuron Responses Attended bar Frequency of spikes Unattended bar 100 msec (Robert Desimone, NIH)

  27. Retina LGN V1 No Attention Effects Here (Relay Station) (Detects Edges) (Color, Form) V4 Attention Effects Here Parietal Cortex (Location, How to reach or act upon) (Shape, Object Recognition) Inferotemporal Cortex

  28. Conclusions from Neuroscientific Evidence: Early visual processing IS affected by selective attention. This is a challenge for a purelate selectionmodel. BUT, it does not mean that late selection is not occurring.

  29. Automatic vs. Voluntary Priming Warning signal Test signal + AA neutral (Posner & Snyder, 1975)

  30. G GG 70% Often predictive S KK G GG 15% “No need to think of P” “think of P! yeah baby!” S KK 70% Often misleading 15% PP P Automatic Priming Automatic Priming Voluntary Priming

  31. High validity Low validity (often misled) P -> P P ->G faster P ->P P ->G Difference between experimental and neutral conditions 15% primed 70% misled 70% primed 15% misled Automatic Priming; Benefit without a cost Voluntary Priming Benefit with cost slower

  32. Automatic vs Voluntary priming (part 2)Neely (1977) • If you see a body part as a Prime, expect a building part as a target. For example, • Body -> door • some pairs were semantically related, but unexpected • body -> heart

  33. Priming Results • Blue: Expected pair • Body -> door • voluntary priming • Evolves with time • Green: Related but unexpected • Body -> heart • automatic priming, followed by a cost from voluntary priming Cost facilitation (ms) Cue-target delay (ms)

  34. Question • Predict pattern of performance when: • the delay between cue and target is very short, • the cue-target delay is longer • For automatic priming • For voluntary priming

  35. 3 meanings of the word ‘Attention’ 1. Selectivity: only aware of a subset of stimuli--selective attention. 2. Capacity Limitations: limited ability to handle different tasks or stimuli at once--divided attention. 3. Sustained mental effort: limited ability to engage in protracted thought, especially on the same subject--vigilance.

  36. Attentional Blink O N K G B P S # # # # # # You will see a stream of letters rapidly presented in the center Group 1: memorize any vowels Group 2: memorize any vowels and red letters

  37. S Target 1 B Encoding into Working Memory N Target 2 O

  38. Attentional Blink: Early or Late Selection? • Instead of letters, use words. • An initial word establishes context (e.g., milk) • Target 2 is a word that is semantically related to the context word or not (e.g., sugar, shoes) • When subjects fail to report T2, look at their brain waves (ERPs) to assess whether the meaning of that target has been processed or not • N 400 (ERP marker of semantic processing)

  39. Spotlight metaphor - metaphors are not right or wrong, they are useful or not…

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