Fig 1.
Each trial block included stimuli in which the visual motion profile matched the inertial motion (normal, solid line) such that the visual stimulus was consistent with moving through a fixed environment.
It also included stimuli in which the velocity profile of the visual stimulus was inverted such that it started and ended at the peak velocity (15 cm/s) while slowing to zero in the middle (inverted, dashed line). Thus, the inverted stimulus was inconsistent with the inertial motion experience.
Fig 2.
Example data from an individual subject (#18) tested in a trial block with a
± 60° offset. With normal velocity visual stimuli (panels A-C), the visual stimulus influenced the perceived inertial heading. Thus, for a visual stimulus shifted to the left. a straightforward inertial heading (0°) is more likely to be perceived as left, which corresponds to the cumulative distribution function being shifted to the right (Panel A). For this subject, the inverted stimulus (panels D-F) had a minimal effect on inertial heading perception. Each small circle represents an individual stimulus presentation, larger circles represent multiple stimulus presentations in proportion to their diameter.
Fig 3.
Effect of visual offset for inverted (striped) and normal (solid) visual stimuli.
The data shown represent all twenty subjects. For no visual offset (zero) the bias is shown as towards the right. When the visual stimulus was offset, the bias was shown towards the visual stimulus so that leftward and rightward biases could be shown together. Error bars represent ±1 SEM. P-values are calculated using a paired T-test and are shown for each offset.
Fig 4.
Effect of visual offset for inverted (striped) and normal (solid) visual stimuli by subject.
Only non-zero visual offsets are included. Bias is plotted towards the visual stimulus offset and represents both leftward and rightward biases. Error bars represent ±1 SEM, which was calculated across all visual offsets (±45, ± 60, and ±75°) collected in that subject.
Fig 5.
Sigma for inverted (striped) and normal (solid) visual stimuli by subject.
All visual offsets were included (including zero) as there was no significant difference based on offset size. Error bars represent ±1 SEM.