E.E.G. alpha feedback--a comparison of two control groups.

It is controversial whether or not veridical feedback is necessary to bring about increases in alpha activity in the feedback situation and has been suggested that the instructional variable may be a crucial determinant of outcome. In this experiment two groups of subjects were both given false feedback. One group was misled into believing that the feedback was contingent. Increases in alpha index occurred only in those subjects who believed that they were receiving contingent feedback, indicating that subjects knowledge and belief concerning the experiment were important in determining the outcome.