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The Week

The Week. Today, Wednesday, 9 /24 More hemisphere asymmetries Tomorrow, Thursday, 9 /25 (OLRI 354) Still more hemisphere asymmetries Friday, 9/26 ( OLRI 354 ) See/participate in a DVF experiment Talk about DVF project Final questions about Monday’s test Monday, 9/29 Test. The Week.

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The Week

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  1. The Week • Today, Wednesday, 9/24 • More hemisphere asymmetries • Tomorrow, Thursday, 9/25 (OLRI 354) • Still more hemisphere asymmetries • Friday, 9/26 (OLRI 354) • See/participate in a DVF experiment • Talk about DVF project • Final questions about Monday’s test • Monday, 9/29 • Test

  2. The Week • Wednesday, 10/1 • Sensation and perception • Thursday, 10/2 • Create pairs/groups • Blitz 2 • On hemisphere asymmetry • ≥ 2008 • See list of acceptable journals under ‘Assignments’ on website

  3. Hemisphere Asymmetries • Split-brain patients • Language in left • Spatial in right • Asymmetric brain damage • Associative agnosias (Farah, 1991) • Abstract/parts in left • Specific/wholes in right • Divided-visual field with normal subjects

  4. Contralateral Organization Left visual field Right visual field Left eye Right eye Optic nerve Optic chiasm LGN SC Thalamus Occipital lobe

  5. Divided-Visual Field • Takes advantage of contralateral organization of visual system • Information presented in left visual field is processed by right hemisphere first • Speed and quality advantage • Information presented in right visual field is processed by left hemisphere first

  6. Logic • If different pattern of responses observed as a function of visual field, conclude hemisphere asymmetry • If no different pattern, could be no hemisphere asymmetry or failed manipulation • Subject did not fixate centrally • Stimuli not presented at correct eccentricity • > 1˚ visual angle

  7. Visual Angle • Inverse tangent of displacement / distance Displacement Distance

  8. Eccentricity Visual Acuity Blind spot Angle from Fixation

  9. Hemisphere Asymmetries • Split-brain patients • Language in left • Spatial in right • Asymmetric brain damage • Associative agnosias (Farah, 1991) • Abstract/parts in left • Specific/wholes in right • Divided-visual field with normal subjects • Categorical vs. coordinate (Kosslyn et al., 1989)

  10. Kosslyn et al. (1989)

  11. Kosslyn et al. (1989) • Categorical representation

  12. Kosslyn et al. (1989) • Coordinate representation

  13. Kosslyn et al. (1989) • Two tasks • Categorical relationship “Above” “Below”

  14. Kosslyn et al. (1989) • Two tasks • Categorical relationship • Coordinate relationship “Near” “Far”

  15. Kosslyn et al. (1989) • Two tasks • Categorical relationship • Coordinate relationship • Present stimuli in divided-visual field

  16. Kosslyn et al. (1989) Response Time (ms) Hemisphere

  17. Kosslyn et al. (1989) • Two tasks • Categorical relationship • Coordinate relationship • Present stimuli in divided-visual field • Categorical judgments faster in left hemisphere than right • Coordinate judgments faster in right hemisphere than left

  18. Hemisphere Asymmetries • Split-brain patients • Language in left • Spatial in right • Asymmetric brain damage • Associative agnosias (Farah, 1991) • Abstract/parts in left • Specific/wholes in right • Divided-visual field with normal subjects • Categorical vs. coordinate (Kosslyn et al., 1989) • Local vs. global (Van Kleeck, 1989)

  19. Van Kleeck (1989) • Navon stimuli • Attend to local or global level • Decide if ‘H’ or ‘S’ H H H H H H H H H H H H H H S S S S S S S S S S S S S S S S S S S S S S S S H H H H S S S S S S S S S S S S S S S

  20. Van Kleeck (1989)

  21. Van Kleeck (1989) • Navon stimuli • Attend to local or global level • Decide if ‘H’ or ‘S’ • Global task: faster in right than left • Local task: faster in left than right (trend)

  22. Hemisphere Asymmetries • Split-brain patients • Language in left • Spatial in right • Asymmetric brain damage • Associative agnosias (Farah, 1991) • Abstract/parts in left • Specific/wholes in right • Divided-visual field with normal subjects • Categorical vs. coordinate (Kosslyn et al., 1989) • Local vs. global (Van Kleeck, 1989) • Abstract vs. specific (Marsolek, 1995, 1999)

  23. Marsolek (1995) Prototypes Distortions

  24. Marsolek (1995) • Learn to categorize shapes Category 1 Category 2 Category 3

  25. Marsolek (1995) • Learn to categorize shapes • Tested on shapes presented in DVF • Old distortions • New distortions • Prototypes

  26. Marsolek (1995)

  27. Marsolek (1995) • Left hemisphere presentations • Fastest for prototypes; equal for old and new distortions • Has stored information common to all distortions rather than distortions themselves • Right hemisphere presentations • Fastest for old distortions; equal for prototypes and new distortions • Has stored information about particular distortion; does not generalize to similar stimuli

  28. Marsolek (1999) • Priming • Facilitation of performance for repeated compared to non-repeated items Brain Cake Nail Frog

  29. Marsolek (1999) • Priming • Facilitation of performance for repeated compared to non-repeated items Primed Brain Grape Suit Cake Smile Nail Frog Nest Unprimed

  30. Marsolek (1999) • Priming • Facilitation of performance for repeated compared to non-repeated items • Subjects view series of pictures and words • Priming phase • Then view series of pictures and name each • 4 conditions during test phase • Same-exemplar primed, different-exemplar primed, word primed, unprimed

  31. Marsolek (1999) Same Exemplar Diff. Exemplar Word Unprimed piano Test Object

  32. Marsolek (1999) Accuracy (%) Hemisphere

  33. Marsolek (1999) • Priming • Facilitation of performance for repeated compared to non-repeated items • Subjects view series of pictures and words • Priming phase • Then view series of pictures and name each • 4 conditions during test phase • Same-exemplar primed, different-exemplar primed, word primed, unprimed • Abstract-category priming in left hemisphere • Specific-exemplar priming in right hemisphere

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