In order to assess Donders's assumption of pure insertion for the response execution stage, we measured the magnitude and time course of response force in the three classical reaction time (RT) tasks: simple RT, go/nogo, and choice RT. Response force was virtually identical for the simple and choice RT tasks (Experiments 1 and 2). However, the go/nogo task yielded more forceful responses than both the simple RT (Experiment 3) and choice RT (Experiments 4 and 5) tasks. These results support Donders's original assumption that the response execution process operates identically in the simple and choice RT tasks. More response activation seems to be generated in the go/nogo task, however, consistent with a motor readiness model.