RESPONSE-TO-STIMULUS INTERVAL DOES NOT AFFECT IMPLICIT MOTOR SEQUENCELEARNING, BUT DOES AFFECT PERFORMANCE

Nissen and Bullemer (1987) reported that implicit motor sequence learn ing was disrupted by the addition of a secondary task. They suggested that this effect was due to the attentional load that the secondary ta sk adds. Recently it has been suggested that the attentional load is n ot critical, but rather that the secondary task affects timing, either by lengthening or by making inconsistent the response-to-stimulus int erval (RSI)--that is, the delay between when a subject makes a respons e and when the next stimulus appears. in six experiments we manipulate d the RSI and found no support for these two hypotheses. An inconsiste nt RSI did not adversely affect implicit motor sequence learning. A lo ng RSI did not affect learning, although under some conditions subject s did not express learning if the RSI was long. These results are inte rpreted as reflecting the effects of attention.