An upper temporal limit of action-effect integration as reflected by motor adaptation.

Motor parameters of simple, repetitive actions like tapping, pinching, or pushing a button differ as a function of their action effects - adding a consistent, immediate sound-effect to such actions leads to a decrease in applied force. This action-effect related motor adaptation occurs only, however, when the sound-effect follows actions within about 200 ms, which has been hypothesized to reflect a temporal limit of action-effect integration. Using a university student sample, the present study replicated the effect of action-sound effect delays on force application. Furthermore, given that the perception of action-effect contingencies, and that of temporal relations are deteriorated in schizophrenia, we explored the relationship between the schizotypy trait and the duration of the action-effect related motor optimization window. Participants pinched a force sensitive device every 3 s on their own volition, which elicited a tone with a delay increasing from block to block in 70 ms steps from 0 to 560 ms. The applied force gradually increased with action-effect delay, with an estimated force optimization window size of 290 ms, confirming the importance of temporal contiguity in action-effect related motor adaptation. A Bayes-factor based analysis provided evidence for no correlation between the motor optimization window size and schizotypy.