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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.

This study focused on individual differences in subjects' capacities for absorption and examined the effects of instructions designed to encourage the use of imaginal processes during electromyography (EMG) biofeedback. Twenty-four high-absorption and 24 low-absorption subjects were assigned to either a biofeedback condition. Each subject participated in two sessions of testing. Results showed that instructional manipulation of imaginal strategies was effective in overcoming the previously observed interference effect of biofeedback for high-absorption subjects. For low-absorption subjects, performance in the two biofeedback conditions was equivalent and, by the end of each session, was appreciably greater than in the no-feedback condition. It was concluded that cognitive mediational strategies employed by subjects are closely related to performance during EMG biofeedback and that these strategies can be manipulated effectively in a manner that appreciably enhances the efficacy of EMG biofeedback as a relaxation.

A review of the frontalis electromyograph biofeedback literature clearly demonstrates that electromyograph biofeedback compares favorably with other relaxation procedures, though some reviewers have prematurely concluded that alternative relaxation treatments are preferable on a cost-benefit basis. Previous statements about the efficacy of biofeedback have oversimplified the data, however, and have failed to recognize sufficiently that reliable effects are associated with different relaxation procedures and specific trait dimensions operating for certain groups of subjects. Definitive statements regarding the efficacy of electromyograph biofeedback and other relaxation treatment modalities need to acknowledge the full complexity of the data and await further research on specific person-treatment interactions.

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