[Unconscious induction of emotions and unintended change in behavior]

The problem of most mood induction procedures in psychological laboratories is located in their demand characteristics. The subjects either have to help change their mood actively, or are at best only passively aware of the induction process. To overcome the necessity of consciousness of the mood induction procedure we developed a technique based on the involuntary tendency to imitate the expression of perceived faces ("emotional infection"). Three different mood induction conditions--operationalized by means of happy, neutral, or sad pairs of faces, which had to be compared in spite of their age--were imbedded in an experiment disguised as, research in perception'. The results show mood influences only in the behavioral measures: Happy induced subjects wrote significantly faster than neutral and sad ones. In contrast, the self description data--measured via mood adjectives--showed no typical changes due to the induction condition. The subjects seemed to be unaware of the cause and the effect of their changed mood.