Fig. 1.

Experimental task. Auditory stimuli consisted of sequences of 5 tones of type A (black) or B (gray) presented in 2 blocks. Each block included standard sequences (71.5%), with 5 repetitions of the same tone (left); expected deviant sequences (14.25%), in which the fifth tone differed from the previous tone in type (middle); and unexpected deviant sequences (14.25%), in which all the tones were identical except the fifth tone was presented in the opposite ear (right). In block 1, tones of type A were used for standard and unexpected deviant sequences and type B for expected deviants. In contrast, in block 2, tones of type B were used for standard and unexpected sequences and type A for expected deviant stimuli. LE, left ear; RE, right ear.