Figure 1.

(A) Diagram showing the velocity contrast task design. Subject’s head remained stationary while the stimuli moved along the frontal audio-visual horizon, using virtual auditory space. The start and end points were ±40–70°, depending on velocity, with a ±15° transition zone in the middle. There were two stimulus intervals along the movement trajectory that had different velocities, V1 and V2 (marked red and blue). In an increase condition, V2 > V1, and V2 < V1 in a decrease condition. (B) An example of a velocity discrimination task design that is used in previous studies. Unlike a velocity contrast task (A), the two stimulus intervals in (B) travel along similar trajectories (marked red and blue), separated in time by an inter stimulus interval (ISI). (C) Velocity profile of the discontinuous condition. The two intervals (V1 and V2) are separated in time by a 1 second gap of silence; this is identical to the ISI used in Carlile and Best⁸. (D) Velocity profile of the continuous condition. The two intervals (V1 and V2) are continuous in time (and space).