How tapping affects talking: Reversals of action-language interaction effects

A growing body of research shows that there is a close functional connection between motor and language systems of the human brain. Behavioural and TMS investigations document a causal influence between language and motor systems, an influence that

is bidirectional and which can be facilitatory or inhibitatory. While it is still not fully clear what determines the sign of the interaction effect (inhibition or facilitation) between action and language, some factors have shown to have an influence on the sign of the effect. A few studies have even managed to successfully reverse the sign of the effect between language and motor processes. This paper provides a short review of these reversals of action-language effects and discusses how this flexibility of motor-language interaction may be explained.