bistability & hysteresis in subjective vertical
DESCRIPTION
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. - PowerPoint PPT PresentationTRANSCRIPT
BISTABILITY & HYSTERESISIN SUBJECTIVE VERTICAL
Bram BielenNatuurwetenschappenMinistage (40 dagen)
Subjective Visual Vertical (SVV)
What is up?
Systematic error in visual verticalclassic interpretation
Aubert effect (A-effect)
SVV deviates in the direction of head tilt.
(Underestimation of body tilt).
Müller effect (E-effect)
SVV deviates in the direction of feet tilt.
(Overestimation of body tilt).
Effects illustrated
ClockWise (CW) & CounterClockWise (CCW)
CWCCW
(ρ)
Rear View
Task
• Adjustment, what is vertical?
Static experiments
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.
Typical static test result
* CW
O CCW
Dynamic experiments
Dynamic experiments
• Subject is rotated for two full cycles 720o
CW or CCW.• Testing during rotation.• Stimulus at 3 sec interval
Dynamic test result
Bistability
Bistability
• Two types of response possible
• At larger tilt angles
Bistability illustrated
18090 2700 360
o A-cluster
Δ E-cluster
Hysteresis
Hysteresis• Response depends on direction of preceding
rotation• LP & SP
Hysteresis illustrated
Research
Why?• Different results dynamic and static experiments
Test Paradigm• Continuous & limited static
• dynamic
Task
• What is the orientation of a line?
Static resultsContinuous Limited
Static resultsContinuous Limited
Static resultsContinuous Limited
Dynamic results
+ CCWo CW
Dynamic results
+ CCWo CW
Conclusions
• Verification of bistability and hysteresis • Bistability in dynamic data
What to do?
• More subjects• Different angles• Other paradigms • Bayesian model
Any questions?