The early component of the premovement readiness potential and its behavioral determinants

Fifteen healthy subjects were asked to randomly select a tick of a mechanical clock which was operating throughout the experiment and to flex their wrist at the chosen tick. The individual averages of EEG recordings collected during the period of the putative decision to begin the task exhibited steep slopes of negativity followed by plateaus. These slopes preceded the selection of the signal sound at varying intervals, the longest interval was 3 s. The grand average of individual averages depicted a waveform whose shape was identical to the early component of the classical readiness potential. Another interesting finding came from experiments with mental counting of clock sounds, which demonstrated that the generation of the first mentally-counted number is preceded by a distinct negative potential shift.