P3b peak latency dependency on the point of information delivery within a stimulus

An acoustic matching experiment was conducted consisting of three quasirandom conditions in which the sequence of tones comprising the second stimulus was changed at the beginning, at the end, or not at all. Latency of maximum positivity (P3b) was measured for each subject between Pz and the averaged mastoids. Evaluation of mismatch conditions demonstrated that peak latency depended on the point of information delivery within the stimulus. Further, peak latency within both mismatch conditions, when adjusted for the timing of tone sequence change, was approximately equally delayed in comparison to match. The implications of the results for information processing models of attention are discussed.