Updating p300 an integrative theory of p3a and p3b
They showed subjects two kinds of visual stimuli: numbers and flashes of light.
Subjects viewed these stimuli one at a time in a sequence.
The P3b can be observed in a variety of experimental contexts.
The second cue type had probabilities that were the reverse of the first.
They observed a positivity around 300 ms after the second click occurred or would have occurred in the case of the single click.
They also had subjects guess how long the interval between clicks might be, and the late positivity occurred 300 ms after the second click.
The P3b is typically observed around 300 ms after each presentation of the target (oddball) stimulus.
A three-stimulus oddball task is exactly like the two-stimulus oddball task, except that in addition to the targets and standards, an infrequent, deviant stimulus such as the letter "D" will appear.