P300, global probability, and stimulus sequence effects in children

The effects of global target stimulus probability and stimulus sequence effects on the amplitude and latency of the P300 event‐related brain potential (ERP) were studied in three groups of children who varied in age (8 to 11, 12 to 15, and 16 to 19 years). ERPs were elicited with an auditory stimulus discrimination paradigm in which subjects were presented with standard (1,000 Hz) and target (2,000 Hz) stimulus tones and instructed to indicate with a finger movement when a target was presented. Two separate paradigms were employed: (a) target stimulus global probability was varied in different conditions at .20, .50, and .80 and (b) target (T) and standard (S) tone presentation sequences were varied by presenting one of four sequence patterns, SS, TS, TT, or ST on each trial. The results demonstrated that increases in target stimulus probability produced a decrease for P300 amplitude and that amplitude sequence effects were quite similar for all three age groups. P300 latency decreased with increases in subject age across both paradigms. The findings suggest that the cognitive changes that occur with developmental maturation do not influence P300 amplitude for either global probability or stimulus sequence manipulations. The theoretical implications of these findings are discussed.