Figure 2.

Intermittent stimulus presentation sequence and corresponding example percepts across trials. In this example, the subject reports the perceived pitch direction of the tone pair as ascending in the first trial (white background) and also ascending in the second trial (blue background). Thus the second trial would be categorized as a “stable” trial because perceived pitch direction remained the same across successive trials. The tone pair in the third trial (red background) was perceived as descending and would be categorized as a reversal trial because perceived pitch direction differed from the immediately preceding trial. Each tone was presented for 400 ms in immediate succession, while trials were separated by a silent ISI of variable duration (500–900 ms). Subjects indicated their perceived pitch direction after each tone pair.