Knowledge and conscious control of motor actions under stress

A recent study by Masters (1992) investigated the effect of stress upon the performance of a well-learned motor skill, golf putting, acquired under implicit and explicit learning conditions. Masters found that stress had a detrimental effect on performance for the explicit learning group but not for the implicit learning group. However, the implicit learning group was required to perform articulatory suppression during the learning trials but not during the stress trials. As such, it is possible that the subjects in the implicit learning group continued to improve during the stress session simply because they were performing an easier task. This paper reports an experiment which re-examines Masters' (1992) conclusions by replicating and extending his method. An additional implicit learning group was included which was required to carry out articulatory suppression during both the learning trials and the stress trials. It was hypothesized that this 'new' implicit learning group would suffer the same disruption to performance as the explicit learning group, providing evidence which would contradict Masters' explanation. Thirty-two subjects were allocated to one of four groups. Performance measures were analysed using two-factor analysis of variance (4 x 5:groups x sessions) with repeated measures on the sessions factor. The main dependent variable was the number of putts successfully completed. The analysis revealed that both the implicit learning groups continued to improve their performance under stress whilst the explicit learning group did not. Despite limitations to both Masters' (1992) and the present study, these results add support to Masters' explicit knowledge hypothesis.