Reinforcement without awareness: II. Word class.

In a previous study of reinforcement without awareness by Lieberman, Sunnucks, & Kirk (this issue), subjects were told that the experiment was on ESP; two words were presented on every trial, and their task was to choose the word the experimenter was thinking of. In fact, reinforcement was contingent on the loudness of the subjects' voices when responding. They found stronger evidence for reinforcement without awareness than in many previous studies, and they attributed their success in part to the reinforcement of a response to which subjects were unlikely to attend. To explore this factor further, we again used an ESP cover story but reinforced subjects for choosing the word in each pair that contained a double letter. We found evidence of reinforcement without awareness in three experiments and also identified two factors that influence these effects: Learning did not occur if subjects (a) were encouraged to test irrelevant hypotheses, or (b) sat in an uncomfortable chair. We speculate that learning without awareness may be more likely when subjects are relaxed and that hypothesis testing and uncomfortable chairs impair such learning because they prevent relaxation.