Fig. 1.

Experimental design. (A) On each trial 5 complex sounds of 50-ms-duration each were presented with a fixed stimulus onset asynchrony of 150 ms between sounds. Four different types of series of sounds were used, the first 2 were prepared using the same 5 sounds (AAAAA or BBBBB), and the second 2 series of sounds were either AAAAB or BBBBA. (B) Each block started with 20–30 frequent series of sounds to establish the global regularity before delivering the first infrequent global deviant stimulus.