PREPARATION FOR ACTION - AN ERP STUDY ABOUT 2 TASKS PROVOKING VARIABILITY IN RESPONSE SPEED

This study focused on the covariation of response speed and event-rela ted potentials during response preparation and on whether these variat ions can be brought under experimental control. Two S1-S2 choice respo nse tasks with temporal uncertainty were conducted. In Experiment 1, S 1 was 100% informative. Fast subjects showed larger P3s with S1 than s low subjects. The terminal CNV (tCNV) increased intraindividually with response speed. In Experiment 2, 50% of S1s were uninformative and th e visual display was designed to attract more attention. Effects of in formation were found on P3 amplitude, on the topography of tCNV, and o n the temporal distribution of response times. Interindividual differe nces disappeared in Experiment 2. The results suggest that group diffe rences in Experiment 1 were due to different strategies of allocating visual attention. Interindividual variations of strategy showed a patt ern of effects different from intraindividual variations of efficiency .