Cognitive and physiologic responses to EMG biofeedback and three types of pseudofeedback during a muscular relaxation task.

40 normal humans were tested in groups of 10 for their ability to reduce frontal muscle tension levels during presentation of veridical auditory biofeedback (BF) or auditory pseudofeedback (PF). A double-blind methodology was used. Three groups of Ss assigned to the PF conditions received a feedback signal that was not contingent on EMG activity but that followed 1 of 3 patterns. One group received a random signal, the 2nd group received a signal that gradually increased in frequency (apparent failure), and the 3rd group received a signal that gradually decreased in frequency (apparent success). Dependent measures included both physiologic (frontal and neck EMG) and subjective reactions to the relaxation task. The different patterns of PF produced reliably different subjective responses, suggesting that the manipulations succeeded in producing unequal nonspecific effects that were unrelated to the feedback contingency. However, these differential subjective effects were not strongly reflected in the physiologic responses since the differences in EMG levels among the 4 groups did not differ significantly at any stage of training. An analysis of the integrity of the double-blind procedure showed that although experimenters were effectively kept blind to group assignment, Ss' responses suggested a response bias as well as the possibility that the double-blind was breached. (11 ref) (PsycINFO Database Record (c) 2016 APA, all rights reserved)