Reinforcement without awareness: I. Voice level

Although some studies have reported that reinforcement can strengthen peopl e's behaviour without their awareness, most studies that have incorporated adequate procedures for assessing awareness have been unsuccessful. Using r igorous procedures, we report two studies designed to provide more scope fo r learning without awareness by making the reinforcement contingency as uno btrusive as possible. Subjects were told that the experiment was on ESP, an d that they were to say which of two words the experimenter was thinking ab out. In fact, reinforcement was contingent on the loudness of the subject's voice when responding. Even though subjects reported no awareness of a rel ationship between trial outcomes and their behaviour, the probability of th e reinforced responses increased significantly over trials in both experime nts. These results support the view that reinforcement can occur without aw areness.