Office Hours Today are Relocated to CCBN

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

6. Feature Integration Theory +

7. Feature Integration Theory G + N

8. Feature Integration Theory +

9. Feature Integration Theory +

10. Feature Integration Theory G +

11. Feature Integration Theory +

12. Feature Integration Theory 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 A PREDICTION: invalid - contralesional target valid - contralesional target invalid - ipsilesional target valid - ipsilesional target

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

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