Generalization of frontalis electromyographic feedback to adjacent muscle groups: a critical review.

The widespread utilization of frontalis electromyographic feedback as a general relaxation strategy far preceded empirical evidence demonstrating its efficacy for this purpose. This article reviews parametric studies testing the association between frontalis reduction and concomitant EMG decreases in nontargeted muscle groups. The current research supports the contention that biofeedback reinforces discriminative responding to a specific muscle group and not generalized relaxation to adjacent muscle groups. Methodological problems are noted, and implications for future research are addressed.