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Attention Everyone knows what attention is. It is the taking ...
Attention Everyone knows what attention is. It is the taking ...
Attention Everyone knows what attention is. It is the taking ...
Attention Everyone knows what attention is. It is the taking ...
Attention Everyone knows what attention is. It is the taking ...
Attention Everyone knows what attention is. It is the taking ...
Attention Everyone knows what attention is. It is the taking ...
Attention Everyone knows what attention is. It is the taking ...
Attention Everyone knows what attention is. It is the taking ...
Attention Everyone knows what attention is. It is the taking ...
Attention Everyone knows what attention is. It is the taking ...
Attention Everyone knows what attention is. It is the taking ...
Attention Everyone knows what attention is. It is the taking ...
Attention Everyone knows what attention is. It is the taking ...
Attention Everyone knows what attention is. It is the taking ...
Attention Everyone knows what attention is. It is the taking ...
Attention Everyone knows what attention is. It is the taking ...
Attention Everyone knows what attention is. It is the taking ...
Attention Everyone knows what attention is. It is the taking ...
Attention Everyone knows what attention is. It is the taking ...
Attention Everyone knows what attention is. It is the taking ...
Attention Everyone knows what attention is. It is the taking ...
Attention Everyone knows what attention is. It is the taking ...
Attention Everyone knows what attention is. It is the taking ...
Attention Everyone knows what attention is. It is the taking ...
Attention Everyone knows what attention is. It is the taking ...
Attention Everyone knows what attention is. It is the taking ...
Attention Everyone knows what attention is. It is the taking ...
Attention Everyone knows what attention is. It is the taking ...
Attention Everyone knows what attention is. It is the taking ...
Attention Everyone knows what attention is. It is the taking ...
Attention Everyone knows what attention is. It is the taking ...
Attention Everyone knows what attention is. It is the taking ...
Attention Everyone knows what attention is. It is the taking ...
Attention Everyone knows what attention is. It is the taking ...
Attention Everyone knows what attention is. It is the taking ...
Attention Everyone knows what attention is. It is the taking ...
Attention Everyone knows what attention is. It is the taking ...
Attention Everyone knows what attention is. It is the taking ...
Attention Everyone knows what attention is. It is the taking ...
Attention Everyone knows what attention is. It is the taking ...
Attention Everyone knows what attention is. It is the taking ...
Attention Everyone knows what attention is. It is the taking ...
Attention Everyone knows what attention is. It is the taking ...
Attention Everyone knows what attention is. It is the taking ...
Attention Everyone knows what attention is. It is the taking ...
Attention Everyone knows what attention is. It is the taking ...
Attention Everyone knows what attention is. It is the taking ...
Attention Everyone knows what attention is. It is the taking ...
Attention Everyone knows what attention is. It is the taking ...
Attention Everyone knows what attention is. It is the taking ...
Attention Everyone knows what attention is. It is the taking ...
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Attention Everyone knows what attention is. It is the taking ...

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  • 1. Attention Everyone knows what attention is. It is the taking possession of the mind, in clear and vivid form, of one out of what seem several simultaneously possible objects or trains of though. Focalization, concentration, of consciousness are of its essence. It implies withdrawal from some things in order to deal effectively with others. William James (1890)
  • 2. Attention Cognitive brain mechanism that facilitates processing
  • 3. Taxonomy for Attention • Modality – Visual – Auditory • Control – Voluntary: intentional, endogenous, "top-down" – Reflexive: automatic, exogenous, "bottom-up" • Duration – Sustained – Momentary
  • 4. Taxonomy for Attention • Modality • Control • Duration • Intensity – Focused – Selective – Divided
  • 5. Attention Properties • Covert • Limited-capacity metaphors – Bottleneck • Early selection: prior to complete perceptual analysis of elementary features • Late selection: after to complete perceptual analysis of elementary features – Searchlight, spotlight, flashlight – Resources • One capacity or many?
  • 6. Attention Theory • Cherry – Cocktail party effect • Auditory selective attention – Dichotic listening paradigm
  • 7. Attention Theory • Broadbent's (1958) information-processing model – Limited-capacity – Early-selection – Top-down – But, can't explain intrusion of unattended input
  • 8. Attention Theory • Late-selection theories – Deutsch & Deutsch – Treisman • Unattended sensory input attenuated at early stage, but not filtered out • High priority unattended input can reach semantic analysis stage
  • 9. Cognitive Psychology of Visual-spatial Selective Attention • Eriksen Flanker Task • Posner Cueing Task • Treisman Visual Search Task • Wolfe Visual Search Task
  • 10. Eriksen Flanker Task Congruent AAA Incongruent EAE Neutral XAX
  • 11. Eriksen Flanker Task Incongruent E A E E A E E A E
  • 12. Eriksen Flanker Task • Searchlight of spatial attention about 1 degree of visual angle 400 450 500 550 0.06 0.5 1 Degree of Visual Angle Congruent Neutral Incongruent
  • 13. Posner Cueing Task • Voluntary orienting of selective attention – Costs and benefits of intended covert attention shifts
  • 14. Other Cueing Tasks • Reflexive orienting of selective attention – Abrupt onset visual stimulus at target location – Attentional "capture" – Time-dependent costs and benefits of unintended covert attention shift • Inhibition of return (>300 ms)
  • 15. Treisman Visual Search Task • Preattentive – Pop-out search • Flat search function • Attentive – Conjunctive search • Serial search function • Moving spotlight • Guided – Conjunctive search of items that share a feature with the target
  • 16. Wolfe Visual Search Task • Costs of voluntary control of attentional spotlight
  • 17. Neurophysiology of Spatial Selective Attention Cortical or subcortical? • Need good temporal resolution to answer this question
  • 18. Neurophysiology of Spatial Selective Attention • ERP and MRF Evidence – Voluntary auditory attention • Hillyard's N1 effect • Woldorff and Hillyard’s P20-50 and M20-50 effects
  • 19. Neurophysiology of Spatial Selective Attention • ERP and MRF Evidence – Voluntary visual attention
  • 20. Neurophysiology of Spatial Selective Attention • ERP and MRF Evidence – Voluntary visual attention • P1 effect for sustained covert attention
  • 21. Neurophysiology of Spatial Selective Attention • ERP and MRF Evidence – Voluntary visual attention • P1 effect for cued covert attention
  • 22. Neurophysiology of Spatial Selective Attention • ERP and MRF Evidence – Reflexive visual attention • P1 effect for cued automatic attention – Enhancement at short ISI – Inhibition at long ISI: Inhibition of return
  • 23. Neurophysiology of Spatial Selective Attention • ERP and MRF Evidence – Voluntary visual attention • P1 effect for visual conjunction search
  • 24. Neurophysiology of Spatial Selective Attention • ERP and MRF Evidence – Voluntary visual attention • N2pc (posterior contralateral) effect for visual conjunction search
  • 25. Neurophysiology of Spatial Selective Attention • Summary of ERP and MRF Evidence – Supports early-selection models • Sensory information enhanced/attenuated by attention to spatial location – Selection occurs at least as early as secondary sensory cortex – Similar effects for both voluntary and reflexive attention
  • 26. Neurophysiology of Spatial Selective Attention • Functional Neuroimaging Evidence – Summary of PET studies of visual selective attention
  • 27. Neurophysiology of Spatial Selective Attention • Functional Neuroimaging Evidence • Attention control – Posner and Petersen's (1990) anterior and posterior attention systems • Anterior - executive control • Posterior - spatial attention
  • 28. Neurophysiology of Spatial Selective Attention • Functional Neuroimaging Evidence – Jovicich et al. (2001) attentional load during motion tracking • Parametric fMRI – Additive factors type methodology that fits polynomial functions to the experimental manipulation levels (L) – Brain Activity = α0 + α1L1 + α2L2 + α3L3 + ...
  • 29. Neurophysiology of Spatial Selective Attention • Functional Neuroimaging Evidence – Hopfinger et al. (2000) spatial cueing study • Event-related fMRI • Top-down attentional control
  • 30. Neurophysiology of Spatial Selective Attention • Animal Single-Unit Evidence • Cortical activity and voluntary orienting – Moran and Desimone (1985) • V4 neurons –Wurtz et al. (1982) • Parietal neurons
  • 31. Neurophysiology of Spatial Selective Attention • Animal Single-Unit Evidence • Subcortical activity and reflexive orienting –Wurtz et al. (1982) • Superior colliculus neurons
  • 32. Hemineglect And Extinction
  • 33. Neglect Failure to acknowledge objects in the field contralateral to the lesion, without perceptual deficit.
  • 34. Extinction • Failure to respond to stimuli in the contralesional field when presented simultaneously with an ipsilesional stimulus.
  • 35. Patients with neglect may: • fail to dress the left side of their body • disclaim “ownership” of left limbs • not recognize familiar people presented on the left side • scan only the right side of a dream • deny the illness
  • 36. Some studies observed that: •Shifting visual field by 10o to the right eases the symptoms for some minutes •Between 38% and 69% of patients recover within 3 months •Extinction tends to persist longer •Neglect deficit can be improved by increasing activation of the sustained attention system
  • 37. Explanatory Hypotheses • LOSS OF ABILITY TO ANALYSE SPATIAL PATTERNS – Neglect occurs only with lesion on the right hemisphere. • ATTENTIONAL DEFICIT – Single cell recordings in monkeys indicate firing in posterior parietal cortex during attention tasks.
  • 38. Explanatory Hypotheses • Arousal – Each side of the brain has separate activation mechanisms. • Representational – Neglect results from inability to form a representation of the whole space.
  • 39. Explanatory Hypotheses • Orienting –Each hemisphere operates attention shifting to the opposite direction in both hemispaces. Hemineglect results from damage in one hemisphere.
  • 40. Posner et al. (1984) Interpretation: Attention happens in 3 stages: disengagement shifting re-engagement
  • 41. Posner et al. (1984) Conclusions: 1.Temporal-parietal lobe is involved in contralesional disengagement 2.Engagement to the new target may rely on frontal sites
  • 42. Raffal and Posner (1987) •Temporal-parietal junction e disengagement •Midbrain e shift •Thalamus e engagemant
  • 43. EVENT TIME (msec) LOCATION Eyes detect stimulus < 80 Primary visual cortex - occipital lobe Preparation for focusing attention to target in the lateral visual field 80 - 100 Parietal-occipital cortex junction (P1) Preparation for precluding attention to contralateral field Preparation for saccadic movement to lock foveal vision into target 100 Meso-parietal + fronto-central Attention to spatial frequency 120 (pick) Extrastriate occipital cortex (Nd2) Selection + attention to frequency + orientation to new image 120 (pick) Posterior dorsal-medial cortex (Anterior P) Attention to spatial frequency 130 (pick) Dorsal extrastriate occipital cortex (Pd) RH - low visual frequency, LH - high frequency 150 (pick) Ventral extrastriate visual cortex (Broad selection N) Preparation for focusing attention to target in the lateral visual field 160 - 180 Parietal-occipital cortex junction (N1) Preparation for precluding attention to contralateral field Discrimination of color and directional patterns 180 - 200 Parietal cortex (N2) Discrimination of color and directional patterns + attention focus Occipital extrastriate + inferior temporal cortices (N2) Selection + attention to frequency + orientation to new image 200 (pick) Posterior dorsal-medial cortex (N2) Preparation for focusing attention to target in the lateral visual field 200 - 250 Parietal-occipital cortex junction (P2) Preparation for precluding attention to contralateral field Allocation of attentional resources to global features ~240 Right parietal temporal cortex Allocation of attentional resources to local features of visual field Left posterior temporal cortex Covert intention without saccadic movement to acknowledge 250 Lateral parietal cortex object in contralateral visual field Selection + attention to frequency + orientation to new image 265 (pick) Posterior dorsal-medial cortex (Anterior-medial N) Maintenance of attention to stimulus in contralateral field 330 - 480 Lateral parietal wide region + saccade, gaze, and maintenance of focus Resetting of system preparing for next shift of attention ~400 Parietal cortex <80 80 - 100 100 120 130 150 160 - 180 180 - 200 200 200 - 250 ~240 250 265 330 - 480 ~400
  • 44. Eglin et al. (1989) Neglect victims perform poorly at target detection on contralesional side, and performance worsens with presentation of stimuli to the ipsilesional side. Neglect victims perform poorly at target detection on contralesional side, and performance worsens with presentation of stimuli to the ipsilesional side.
  • 45. Volpe et al. (1979) Neglect patients can make ‘accurate’ same-different judgments between stimuli in the intact versus neglected visual field, even when they cannot identify the neglected item. Neglect patients can make ‘accurate’ same-different judgments between stimuli in the intact versus neglected visual field, even when they cannot identify the neglected item.
  • 46. Grabowecky et al. (1993) Target detection in the neglected field is enhanced by increasing stimuli in the same field. Target detection in the neglected field is enhanced by increasing stimuli in the same field.
  • 47. Neglect victims seem to process color, shape, and even meaning in the damaged hemifield, without ever being aware of the stimuli.
  • 48. Bisiach & Luzzatti (1978) Conclusion: Attention to material in visual-spatial memory is affected by damage in the parietal and posterior temporal lobes.
  • 49. Behrmann & Tipper (1994) Neglect can be locked to an object configuration and rotate with it. Neglect can be locked to an object configuration and rotate with it.
  • 50. Balint’s Syndrome Inability to attend to two objects at the same time. Difficulty establishing relationship between separate objects. Inability to attend to two objects at the same time. Difficulty establishing relationship between separate objects.

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