Fig. 1.

Illustration of the four stimulus conditions in the EEG MMN experiment. In each condition, a sequence of pairs of harmonic tones with fundamental frequencies of 196 Hz (low tone denoted by black notes) and 466 Hz (high tone denoted by gray notes) was used. In the test conditions, the tones were synchronous on 80% of trials. One test condition (early test condition) had low tones or high tones presented early, on 10% of trials each. The other test condition (late test condition) had the low or high tones presented late on 10% of trials each. The two corresponding control conditions consisted of low and high tones presented early (50% of trials each) and low and high tones presented late (50% of trials each).