The illustration shows the relationship of occurrences between the deviation and math tasks. D: deviation task onset. M: math task onset. (a) Case 1: math task presents 400 ms before the deviation task onset. (b) Case 2: math and deviation tasks occur at the same time. (c) Case 3: math task presents 400 ms after the deviation task onset. (d) Case 4: only math task presents. (e) Case 5: only deviation task occurs. The bottom insets show the onset sequences of the two tasks.