Figure 2. Schematic of the streaming task.

The streaming task is a one-interval, two- alternative, forced-choice task requiring a monkey to report whether he heard one or two auditory streams by moving a joystick to the right (one stream) or left (two streams). When the frequency difference between tones A and B was ≤1 semitone or ≥10 semitones, the monkeys received a juice reward for reporting the correct answer. For all other frequency differences, the monkeys received a reward on 50% of randomly selected trials; the decision to reward was made independent of their behavioral report.