Motor imagery entails task-set inhibition

Motor imagery requires the covert execution of a movement without any overt motor output. Previous studies indicated that motor imagery results in the prolonged inhibition of motor commands. In the present study, we investigated whether motor imagery also leads to the inhibition of more abstract task representations. To do so, we investigated the effect of motor imagery on n - 2 repetition costs, which offer an index of the extent to which task representations are inhibited. Participants switched among three tasks and among two response modes: overt and covert responding (i.e., motor imagery). N - 2 repetition costs were present when the current trial required an overt response but absent when the current trial required a covert response. Furthermore, n - 2 repetition costs were more pronounced when trial n - 1 required a covert response rather than an overt response. This pattern of results suggests that motor imagery also leads to the inhibition of abstract task representations. We discuss our findings in view of current conceptualizations of motor imagery and argue that the inhibitory mechanism entailed by motor imagery targets more than motor commands alone. Finally, we also relate our findings to the mechanisms underlying the inhibition of task representations.