Figure 1. Heading discrimination task.
(A) Subjects are seated on a motion platform in front of a screen displaying 3D optic flow. They perform a heading discrimination task based on optic flow (visual condition), platform motion (vestibular condition), or both cues in combination (combined condition). Coherence of the optic flow is constant within a trial but varies randomly across trials. (B) The subjects' task is to indicate whether they are moving rightward or leftward relative to straight ahead. Both motion direction (sign of h) and heading angle (magnitude of ) are chosen randomly between trials. (C) The velocity profile is Gaussian with peak velocity ∼1 s after stimulus onset.