RESULTS
ERPs Elicited by Nontarget Stimuli

As is common in ERP studies in which the electroen-cephalogram (EEG) is recorded from more than a fewscalp sites, the entire data set was used to describespatial scalp distributions, whereas statistical analyseswere performed on selected sets of scalp sites. Theanalyzed sites were chosen to cover the distribution ofeach component as observed in the topographic maps,as well as to cover an area sufficiently large to allow adistribution-based distinction among components andcomparisons across tasks. With slight variations amongtasks (specified where relevant),the dependent variableswere (1) mean amplitudes calculated for time rangesduring which the ERPs elicited by different stimulustypes were distinct by visual observation, (2) mean am-plitudes calculated for more restricted time ranges thatencompassed the relevant component in each task, (3)the peak latency (defined as the latency of the mostnegative point within the same time range), and (4) thelatency to the onset of these components.The onset wasdefined as the first latency at which the distinctionbetween conditions was significant, determined bypoint-by-point □□tests. On the basis of the observed dis-tributions, the statistical analysis of ERPs elicited in thevisual task were limited to posterior and posterior tem-poral areas (OM1/2, O1/2, PO3/4, and T5/6), whereas inall other tasks the sites of interest covered the middleand anterior temporal lobes as well as lateral aspects of the precentral and frontal areas (TP7/8, T3/4, C3/4, FC1/2, FC5/6, F3/4, and F7/8).