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BISTABILITY & HYSTERESIS IN SUBJECTIVE VERTICAL

BISTABILITY & HYSTERESIS IN SUBJECTIVE VERTICAL. Bram Bielen Natuurwetenschappen Ministage (40 dagen). Subjective Visual Vertical (SVV). What is up?. Systematic error in visual vertical classic interpretation. Aubert effect (A-effect). SVV deviates in the direction of head tilt.

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BISTABILITY & HYSTERESIS IN SUBJECTIVE VERTICAL

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  1. BISTABILITY & HYSTERESISIN SUBJECTIVE VERTICAL Bram Bielen Natuurwetenschappen Ministage (40 dagen)

  2. Subjective Visual Vertical (SVV) What is up?

  3. Systematic error in visual verticalclassic interpretation

  4. Aubert effect (A-effect) SVV deviates in the direction of head tilt. (Underestimation of body tilt).

  5. Müller effect (E-effect) SVV deviates in the direction of feet tilt. (Overestimation of body tilt).

  6. Effects illustrated

  7. ClockWise (CW) & CounterClockWise (CCW) CCW CW (ρ) Rear View

  8. Task • Adjustment, what is vertical?

  9. Static experiments

  10. Static experiments • Subjects are rotated to an angle (ρ) between 0 and 360º, CW or CCW. • Testing begins after final tilt angle is reached. • Examples: 30 sec / 60 sec.

  11. Typical static test result * CW O CCW

  12. Dynamic experiments

  13. Dynamic experiments • Subject is rotated for two full cycles 720o CW or CCW. • Testing during rotation. • Stimulus at 3 sec interval

  14. Dynamic test result

  15. Bistability

  16. Two types of response possible At larger tilt angles Bistability

  17. Bistability illustrated o A-cluster Δ E-cluster 0 90 180 270 360

  18. Hysteresis

  19. Hysteresis • Response depends on direction of preceding rotation • LP & SP

  20. Hysteresis illustrated

  21. Research

  22. Why? • Different results dynamic and static experiments

  23. Test Paradigm • Continuous & limited static • dynamic

  24. Task • What is the orientation of a line?

  25. Static results Limited Continuous

  26. Static results Limited Continuous

  27. Static results Limited Continuous

  28. Dynamic results o CW + CCW

  29. Dynamic results o CW + CCW

  30. Conclusions • Verification of bistability and hysteresis • Bistability in dynamic data

  31. What to do? • More subjects • Different angles • Other paradigms • Bayesian model

  32. Any questions?

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