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Prosopagnosia and Face-Specific Mechanisms

Prosopagnosia and Face-Specific Mechanisms. Brad Duchaine Vision Sciences Laboratory Harvard University http://www.faceblind.org. The nature of cognitive specializations. Domain-specific—mechanisms specialized for particular types of content. e.g.-speech, faces.

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Prosopagnosia and Face-Specific Mechanisms

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  1. Prosopagnosia and Face-Specific Mechanisms Brad Duchaine Vision Sciences Laboratory Harvard University http://www.faceblind.org

  2. The nature of cognitive specializations Domain-specific—mechanisms specialized for particular types of content. e.g.-speech, faces. Domain-general—mechanisms specialized for particular processing tasks. e.g.-recognition, reasoning.

  3. Prosopagnosia: Acquired & Developmental Long considered an extremely rare condition www.faceblind.org contacted by 400 prosopagnosics Majority are developmental

  4. Living with Prosopagnosia “While traveling, I had a stopover at O'Hare and I was approached by a stranger in the lounge area. It took 10-15 seconds of casual conversation before realizing who it was. It was my brother.” “I think prosopagnosia has worsened my current depression, if it’s not the root cause of it. This condition always affects my ability to form normal social links to others. I prefer to be a recluse because I can’t confidently function any other way. My avoidance of people to interact with socially is nearly phobic.”

  5. Explanation in prosopagnosia Within-Class Mechanism Configural Processing Mechanism Non-Decomposable Mechanism Curvature Mechanism Rapid Expertise Mechanism Extended Expertise Mechanism Face-Specific Mechanism

  6. Case History: Developmental Prosopagnosic Edward • 53-year-old right-handed man. • Ph.D.s in physics and theology. • Aware of problems as a child. • Knows of no head trauma. • MRI showed no abnormalities. • General face processing impairment. • Reports no difficulties with object recognition. • No navigational difficulties.

  7. Case History: Acquired Prosopagnosic LJ • 16-year-old high school student. • Incident at school dance. • Knows of no head trauma. • Incidents over last few years. • Feels lonely in world devoid of facial information. • Impairment beginning with face detection.

  8. Case History: Acquired Prosopagnosic LJ • 16-year-old high school student. • Incident at school dance. • Knows of no head trauma. • Incidents over last few years. • Feels lonely in world devoid of facial information. • Impairment beginning with face detection. • Reports normal object recognition. • Navigational skills are deteriorating. • CAT, MRI, and EEG are normal.

  9. Edward’s Face Recognition Controls 25 faces 21.6 (2.5) Edward 3 Famous Face Recognition Duchaine & Nakayama (2004) Neuron

  10. LJ’s Face Recognition Famous Face Recognition LJ Controls 28.8 (3.2) 1 32 faces

  11. fMRI procedure • Localizer: Block-design with 5 stimulus classes. • Faces Scenes Bodies Objects Scrambled

  12. LJ Edward FFA: Faces - Objects Controls

  13. LJ Edward PPA: Places - Objects Controls

  14. Control Edward LJ EBA: Bodies - Objects

  15. Repetition decrease in FFA % Signal Change to Face 2 Different Face Same Face Face 1 Face 2 Face 1 Face 2

  16. % Signal Change Same / % Signal Change Diff

  17. Explanations for prosopagnosia • Configural Information • (Levine & Calvanio, 1989) Proposed Domains Predicted Impairments • Upright faces (Farah, 1996) • Within-class recognition • (Damasio et al., 1982) • Non-decomposable objects • (Farah, 1991) ? ? • Curved surfaces • (Kosslyn et al., 1995; Laeng & Caviness, 2001) • Rapid Expert Classes • (Gauthier et al., 1999) • Extended Expert Classes • (Carey & Diamond, 1986; Carey, 1992) A mechanism isn’t working, but what is its domain?

  18. Within-Class Mechanism Mechanism for recognizing individual items. (Damasio et al., 1982)

  19. Within-Class Mechanism Faces Sunglasses Horses Guns Cars Houses Tools Landscapes

  20. Faces: Individual Scores A’

  21. Response time z scores

  22. Non-Decomposable Mechanism Mechanism for representing objects difficult to decompose into parts (Farah, 1991) May require holistic strategy. Hypothesis not explicit about what objects qualify.

  23. Curvature Mechanism Mechanism for representing curved surfaces (Kosslyn et al., 1995; Laeng & Caviness, 2001). Laeng & Caviness (2001): Dogs, glasses, and cars.

  24. Configural Processing Mechanism Upright faces activate configural processing. Face-specific? or General purpose? Domain-general mechanism for configural processing (Levine & Calvanio, 1989)

  25. Parts Spacing Parts Spacing

  26. Spacing Changes % Correct % Correct Part Changes Spacing Changes % Correct % Correct Part Changes

  27. Configural Processing Mechanism Normal House spacing inconsistent with: Configural processing hypothesis Non-decomposable hypothesis Demonstrates face-specific impairment.

  28. Non-decomposable hypothesis Curvature hypothesis Upright vs Inverted

  29. Face Matching: Upright versus Inverted

  30. Face Matching: Upright versus Inverted % Correct Controls Edward LJ

  31. Face Matching: Upright versus Inverted Edward processes upright and inverted faces similarly. No special processing for upright faces. Normal inverted performance inconsistent with: Non-decomposable hypothesis Curvature hypothesis LJ performs worse with upright faces than inverted faces. Upright representations sent to “black hole”.

  32. Rapid Expertise Mechanism Mechanism for recognition of items from expert categories (Gauthier et al., 1997, 1999)

  33. Rapid Expertise Mechanism Edward not a face expert after 53 years. LJ has lost his expertise with faces.

  34. Rapid Expert Mechanism Eight sessions of training (Gauthier & Tarr, 2002). Sessions 1-4: Between 495-680 Test Trials Sessions 5-8: 180 Test Trials Yes Naming T (for Triz) No Triz Verification

  35. Naming Naming Scaled % Correct Session

  36. Naming Scaled % Correct Session

  37. Individual Verification Scaled % Correct Session

  38. Individual Verification Scaled % Correct Session

  39. Family Verification % Correct Session

  40. Family Verification % Correct Session

  41. Rapid Expertise Mechanism • Within-class hypothesis • (Damasio et al., 1982) Greeble results are inconsistent with: • Curvature hypothesis • (Kosslyn et al., 1995; Laeng & Caviness, 2001) Results are inconsistent with hypothesis

  42. Extended Expertise Mechanism Mechanism for recognition of items from expert categories (Diamond & Carey, 1986)

  43. Extended Expertise Mechanism

  44. Extended Expertise Mechanism

  45. Extended Expertise Mechanism

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