DUAL ADAPTATION OF APPARENT CONCOMITANT MOTION CONTINGENT ON HEAD ROTATION FREQUENCY

Perceived movement of a stationary visual stimulus during head motion was measured before and after adaptation intervals during which partic ipants performed voluntary head oscillations while viewing a moving sp ot. During these intervals, participants viewed the spot stimulus movi ng alternately in the same direction as the head was moving during eit her.25- or 2.0-Hz oscillations, and then in the opposite direction as the head at the other of the two frequencies. Postadaptation measures indicated that the visual stimuli were perceived as stationary only if traveling in the same direction as that viewed during adaptation at t he same frequency of head motion. Thus, opposite directions of spot mo tion were perceived as stationary following adaptation depending on he ad, movement frequency. The results provide an example of the ability to establish dual (or ''context-specific'') adaptations to altered vis ual-vestibular feedback.