Cortical processing of simultaneous hand and foot movements: Evidence from event-related potentials


  • Much of this article was prepared while the first author was a sabbatical visitor at the Psychological Institute of the University of Tübingen, Germany, whose support and hospitality is gratefully acknowledged. The studies were supported by an Otago research grant. We are grateful to Hartmut Leuthold, John Polich, and an anonymous reviewer for helpful comments on a previous version of the article.

Address correspondence to: Jeff Miller, Department of Psychology, University of Otago, PO Box 56, Dunedin 9054, New Zealand. E-mail:


The motor processes involved in generating simultaneous hand and foot movements were studied by recording event-related potentials (ERPs) during reaction time tasks in which participants made hand and foot movements either alone or in combination with one another. In particular, we assessed whether the motor potentials generated during combined movements were simply superpositions of the potentials generated during the individual movements in isolation. ERPs generated during single-limb movements replicated previously observed motor potentials, and those generated during both the execution (Experiment 1) and preparation (Experiment 2) of combined movements showed some deviations from the predictions of the superposition hypothesis, suggesting the presence of neural interactions between the hand and foot movement systems during preparation and execution of these actions.