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Attention & Scene Analysis 2

Attention & Scene Analysis 2. PSY 295 – Sensation & Perception Christopher DiMattina , PhD. Today’s topics. Attentional blink Scene perception Neurobiology of attention. Attentional Blink. Attention in time. We talked about spatial attention last lecture

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Attention & Scene Analysis 2

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  1. Attention & Scene Analysis 2 PSY 295 – Sensation & Perception Christopher DiMattina, PhD

  2. Today’s topics • Attentional blink • Scene perception • Neurobiology of attention PSY 295 - Grinnell College - Fall 2012

  3. Attentional Blink PSY 295 - Grinnell College - Fall 2012

  4. Attention in time • We talked about spatial attention last lecture • How are attention resources deployed in time? PSY 295 - Grinnell College - Fall 2012

  5. RSVP task • Rapid serial visual presentation • Show stimuli in rapid succession – need to detect two different target stimuli – say an ‘X’ and a white letter • Can detect a single target at rate of 8-10 targets/sec PSY 295 - Grinnell College - Fall 2012

  6. RSVP task PSY 295 - Grinnell College - Fall 2012

  7. Attentional blink • If T2 appears 200-300 msec after T1, and we correctly detect T1, we are impaired at detecting T2 PSY 295 - Grinnell College - Fall 2012

  8. Fishing metaphor • Imagine fishing in a dirty stream (boots, tires, etc…) • Dip net into water when you see a fish • If another fish swims by while you are busy with the first fish, you will miss it! PSY 295 - Grinnell College - Fall 2012

  9. Good performance for 100 msec • This corresponds to getting two fish in your “attention net” PSY 295 - Grinnell College - Fall 2012

  10. First-person shooter games • Video game players do better than other people. Any thoughts as to why? PSY 295 - Grinnell College - Fall 2012

  11. Green & Bavelier (2003) • Studied visual selective attention in first person shooter video-game players (VGP) and non-video game players (NVGP) • VGPS outperformed NVGP’s at varied spatial and temporal attention tasks PSY 295 - Grinnell College - Fall 2012

  12. Flanker compatibility task • Subjects detect diamond or square in one of six circles • Compatible or incompatible figure shown outside • Compatibility benefit disappears for hard task in NVGPs PSY 295 - Grinnell College - Fall 2012

  13. Enumeration task • VGPS were better at telling how many squares briefly flashed PSY 295 - Grinnell College - Fall 2012

  14. Better attention over space • VGPs better at telling which of six arms a target was flashed • Advantage for all eccentricities PSY 295 - Grinnell College - Fall 2012

  15. Question • Can you think of a possible flaw with this experiment? PSY 295 - Grinnell College - Fall 2012

  16. Training NVGPs • Two groups of NVGP’s were trained with two different games – tetris (control) and a first-person shooter game • First person shooter game subjects improved in attention tasks PSY 295 - Grinnell College - Fall 2012

  17. Play first-person shooter games for better attention PSY 295 - Grinnell College - Fall 2012

  18. Scene Perception PSY 295 - Grinnell College - Fall 2012

  19. Gist perception • How do we know this is a kitchen before we see the individual objects (sink, oven, etc…)? PSY 295 - Grinnell College - Fall 2012

  20. Ensemble statistics PSY 295 - Grinnell College - Fall 2012

  21. Ensemble statistics PSY 295 - Grinnell College - Fall 2012

  22. Two pathways PSY 295 - Grinnell College - Fall 2012

  23. Non-selective pathway quickly computes scene properties • People can monitor stream of images @ 100 msec per image • Can move eyes to one of two pictures containing an animal in only 120 msec • Can discriminate natural from man-made scenes with only 19 msec of exposure to scene • 20-50 msec to recognize just one object PSY 295 - Grinnell College - Fall 2012

  24. Image statistics • May be using very low-level properties of scenes like spatial frequency content to discriminate categories • Similar semantic categories of scenes have similar spatial frequency components and low-level structure PSY 295 - Grinnell College - Fall 2012

  25. Similar categories, similar structure PSY 295 - Grinnell College - Fall 2012

  26. We are good at recognizing scenes PSY 295 - Grinnell College - Fall 2012

  27. Which ones did you see? PSY 295 - Grinnell College - Fall 2012

  28. Answers PSY 295 - Grinnell College - Fall 2012

  29. Good at gist, bad with details PSY 295 - Grinnell College - Fall 2012

  30. Neurobiology of Attention PSY 295 - Grinnell College - Fall 2012

  31. Attention modulates brain activity from O’Craven et al (1997) PSY 295 - Grinnell College - Fall 2012

  32. Attention modulates brain activity • Enhances neural responses to attended features PSY 295 - Grinnell College - Fall 2012

  33. Attention modulates brain activity PSY 295 - Grinnell College - Fall 2012

  34. Single cell effects • Attention biases competition by shrinking RF around attended object in V4 and IT (Moran & Desimone1985) PSY 295 - Grinnell College - Fall 2012

  35. McAdams & Maunsell • For single stimulus in RF, attention has multiplicative effect on tuning curves PSY 295 - Grinnell College - Fall 2012

  36. Spatial modulation PSY 295 - Grinnell College - Fall 2012

  37. Disorders of attention PSY 295 - Grinnell College - Fall 2012

  38. Parietal lobe lesions • Patients with right parietal lobe lesions neglect the left half of visual space. Not due to basic sensory deficits. PSY 295 - Grinnell College - Fall 2012

  39. Neglect PSY 295 - Grinnell College - Fall 2012

  40. Neglect • May be object-centered as well as spatial PSY 295 - Grinnell College - Fall 2012

  41. Extinction • Can only deploy attention to bad field if there are no competing objects in the good field • Objects in good field “extinguish” those in the bad field • Perhaps a milder form of neglect PSY 295 - Grinnell College - Fall 2012

  42. Balint syndrome • Bilateral parietal lesions • Cannot disengage attention without blinking • Can only attend to one object at once (simultagnosia) PSY 295 - Grinnell College - Fall 2012

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