Figure 1.

(a) Schematic of a tone cloud stimulus. Each stimulus consisted of brief tone pips at random frequencies (with two channels per octave) and random onset times. (b) Illustration of the stimuli and task. The NTC stimuli were formed by concatenating three (0.5 s each) segments of tone cloud. The RTC consisted of three repetitions of a single tone cloud segment of 0.5 s. Both NTC and RTC were generated anew for each trial. The RefTC also consisted of three repetitions of a single segment of 0.5 s but, importantly, the same stimulus was used for all trials. In the experiment, subjects were presented with a single stimulus and the task was to detect repetitions in the stimulus by pressing one button if repetitions were detected and another if no repetitions were detected.