A priming method for investigating the selection of motor responses

We describe a priming method for investigating the mechanisms underlying the selection of motor responses. The empirical question addressed with the method is how the choice reaction time for a response depends on its relationship to a response that the subject was primed to perform. We explore the method in a study of manual response selection where we investigate the effects of requiring that two possible responses use the same finger or hand. A requirement of the method — that subjects get ready to perform primed responses only — is not met in some conditions of the experiment. When the two possible responses are made with different hands, it appears that multiple response preparation occurs prior to detection of the reaction signal, whereas when the two possible responses are made with different fingers of the same hand it appears that advance preparation is limited to a single response. This finding implies that subjects engage in different kinds of response preparation depending on the relationship between the alternative possible responses. We discuss the implications of this hypothesis for the priming method introduced here as well as for theories of response selection generally.