Fig. 3.

Exemplary performance (symbols) and fitted psychometric functions (lines) for depth discrimination of two alternating sound sources as a function of their distance difference in Exp. II. Performance is best in the AM condition (green) where the subject performed an active head motion and worse in the SSM condition (purple) where the subject was stationary, but the sound sources moved past him or her. When the subject was moved by the motion platform past the virtual sound sources (PM, blue), performance was intermediate. Without both subject- and sound-source motion (NM), the subject could not solve the task even at the largest distance difference of 68 cm (single black star). Therefore, full psychometric functions were not obtained in the NM condition.