Influence of centrifugal force on angular velocity estimation.

In darkness, subjects were positioned face forward (or backward, resp.) on a rotating disk at a radial distance r of 0-1.6 m. They were then accelerated within 0.8 s to a constant rotation (omega = 0.35-0.87 rad/s), and successively indicated whenever they felt turned through 180 degrees. Fairly veridical at first, these indications lagged progressively as though subjective velocity declined exponentially to zero. Plots of ordinal number of indications over time of indication revealed idiosyncratic time constants (20-90 s) that were independent of disk velocity at r = 0, but increased with radial distance, namely, with r omega 2, hence depended on centrifugal force. When, after constant rotation of at least 2 min the subjects were stopped (within 1.2 s), and asked to indicate 180 degrees turns as above, the time constants of all subjects were independent of radius and disk velocity, as expected, if the added orthogonal force caused the prolonged time constants in the former paradigm.