Role of the feedback signal in electromyograph biofeedback: The relevance of attention.

This article describes two experiments designed to examine the hypothesis that the critical role of the feedback signal in frontalis electromyograph (EMG) biofeedback is an attentional one. In both experiments, high- and low-absorption subjects were assigned to either a biofeedback condition, a no-feedback condition, or an attentional demand condition in which external stimuli, related to relaxation, were presented as an attentional focus. The two experiments differed essentially in the type of attentional demand condition that was employed and varied the compelling nature of the demand on subjects for an external attentional focus. The pattern of results was consistent with the attentional hypothesis. For low-absorption subjects, performance in the biofeedback and attentional demand conditions was equivalent and appreciably greater than in the no-feedback condition. For high-absorption subjects, an interference effect of biofeedback was observed, but data indicated a similar interference effect on the performance of subjects when the attentional demand condition was most compelling. The pattern of results obtained point to the special relevance of attentional processes and highlight their lack of emphasis in contemporary theoretical models of EMG biofeedback.