Abstract
Some characteristic problems should be resolved in development of biofeedback devices besides common problems mostly found in other ME devices. They are the modality of the feedback stimulus, quantitative or binary feedback, immediate or delayed feedback, selection of the response, elimination of noise and artifact, etc. Biofeedback training has been said fo be free from a harmful after-effect. There is, however, a possibility that noise and artifact have not only a disturbing effect but also a harmful effect in the feedback training. For instance, an increment of alpha waves is often tried for tension reduction. However, so far only a simple filter is used to select alpha waves, a pseudo-feedback signal is triggered by the abnormal muscle activities or the body movements. If the subject is trained in such a situation, an increment of tension far from tension reduction will be learned. Elimination of noise or artifact is of importance especially in a small type biofeedback device which is available in any place. We are developing a new biofeedback device equiped a logic circuit to prevent the effect of noise and artifact.
