Fig. 1.

A schematic illustration of the stimuli used in the study. Tone pairs (either ascending or descending in within-pair pitch change) were presented in an alternating order from the high and low streams (HP = high pair, LP = low pair). Within both streams, the position of the pairs varied randomly over a wide pitch range. A pitch area where no pairs were presented separated the high and low streams from each other (dashed rectangle). (A) In the Same-direction condition, the standard pairs (white) were ascending both in the high and low streams and the occasional deviant pairs (black) descending. (B) In the Different-direction conditions, the low-stream standard pairs were ascending and the deviant pairs descending whereas in the high stream the directions were reversed.