1. Office Hours Today are Relocated to CCBN rm EP1216 (the receptionist can help you find me)

2. Feature Integration Theory What term does Treisman use to describe the bundle of features at a specific location?

3. Feature Integration Theory Object Files are mental (neural?) representations of the features associated with an object –whenever an object is selected by attention its features are bound and an object file is opened –when the features of that object change, the object file is updated

4. Feature Integration Theory How did Treisman et al. test whether the visual system uses object files?

5. Feature Integration Theory Priming: observers are faster to respond to something they’ve just seen

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12. What Letter?

13. Feature Integration Theory What was the result?

14. Feature Integration Theory What was the result? –Naming was faster if the prime occurred in the same object, even though the object had moved

15. Feature Integration Theory What was the result? –Naming was faster if the prime occurred in the same object, even though the object had moved Interpretation?

16. Feature Integration Theory What was the result? –Naming was faster if the prime occurred in the same object, even though the object had moved Interpretation? –visual system establishes object files and updates them as the location and features of the object change

17. The Physiology of Attention

18. Physiology of Attention Neural systems involved in orienting Neural correlates of selection

19. Disorders of Orienting Lesions to parietal cortex can produce some strange behavioural consequences Parietal Lobe

20. Disorders of Orienting Lesions to parietal cortex can produce some strange behavioural consequences –patients fail to notice events on the contralesional side –Patients behave as if they are blind in the contralesional hemifield

21. Disorders of Orienting Lesions to parietal cortex can produce some strange behavioural consequences –patients fail to notice events on the contralesional side –Patients behave as if they are blind in the contralesional hemifield but they are not blind Called Hemispatial Neglect

22. Disorders of Orienting Patients will often “neglect” half of their visual field

23. Disorders of Orienting Hypothesis: Parietal cortex somehow involved in orienting attention into contralesional space

24. Disorders of Orienting Posner and colleagues –Use cue-target paradigm to investigate attentional abilities of parietal lesion patients

25. Disorders of Orienting Posner and colleagues –Use cue-target paradigm to investigate attentional abilities of parietal lesion patients –Prediction ?

26. Disorders of Orienting Posner and colleagues –Use cue-target paradigm to investigate attentional abilities of parietal lesion patients –Prediction: stimuli in ipsilesional field always faster than stimuli in contralesional field and cues don’t matter

27. Disorders of Orienting valid - contralesional target valid - ipsilesional target invalid - contralesional target invalid - ipsilesional target A PREDICTION:

28. Disorders of Orienting Results: Valid cue in contralesional field is effective invalid- contralesional target valid - contralesional target invalid - ispilesional target valid - ipsilesional target Results: Severe difficulty with invalidly cued contralesional target

29. Disorders of Orienting Interpretation: –Patients have difficulty disengaging attention from good hemifield so that it can be shifted to contralesional hemifield

30. Disorders of Orienting Interpretation: –Patients have difficulty disengaging attention from good hemifield so that it can be shifted to contralesional hemifield –Parietal cortex is somehow involved in disengaging attention

31. Disorders of Orienting Disengage - Shift - Engage Model –Parietal Cortex notices events and disengages attention

32. Disorders of Orienting Disengage - Shift - Engage Model –Parietal Cortex notices events and disengages attention –Superior Colliculus moves attention

33. Disorders of Orienting Disengage - Shift - Engage Model –Parietal Cortex notices events and disengages attention –Superior Colliculus moves attention –Pulvinar Nucleus reengages attention

34. Disorders of Orienting Disengage - Shift - Engage Model –Parietal Cortex notices events and disengages attention –Superior Colliculus moves attention –Pulvinar Nucleus reengages attention –Entire process is under some top-down control from Frontal Cortex

35. Disorders of Orienting Orienting mechanism can be interfered with in normal brains

36. Disorders of Orienting Orienting mechanism can be interfered with in normal brains –changes that are not accompanied by transients are hard to detect

37. Disorders of Orienting Orienting mechanism can be interfered with in normal brains –changes that are not accompanied by transients are hard to detect e.g. building appearing slowly orienting mechanism scans the scene aimlessly

38. Disorders of Orienting Orienting mechanism can be interfered with in normal brains –changes that are not accompanied by transients are hard to detect e.g. building appearing slowly orienting mechanism scans the scene aimlessly –changes accompanied by full-field transients are hard to detect e.g. change blindness orienting mechanism is blinded by the transient

39. Next Time: Neural correlates of selective attention