Relative effectiveness and validity of mood induction procedures: a meta-analysis

The effectiveness and validity of 11 important mood induction procedures (MIPs) were comparatively evaluated by meta-analytical procedures. Two hundred and fifty effects of the experimental induction of positive, elated and negative, depressed mood in adult, non-clinical samples were integrated. Effect sizes were generally larger for negative than for positive mood inductions. The presentation of a film or story turned out to be most effective in inducing both positive and negative mood states. The effects are especially large when subjects are explicitly instructed to enter the specified mood state. For elated mood, all other MIPs yielded considerably lower effectiveness scores. For the induction of negative mood states, Imagination, Velten, Music, Social Interaction and Feedback MIPs were about as effective as the Film/Story MIP without instruction. Induction effects covaried with several study characteristics. Effects tend to be smaller when demand characteristics are controlled or subjects are not informed about the purpose of the experiment. For behavioural measures, effects are smaller than for self-reports but still larger than zero. Hence, the effects of MIPs can be partly, but not fully due to demand effects.     

Effects of negative mood on performance: reduced capacity or changed processing strategy?

Two theoretical positions are often used to explain the effects of negative mood on performance: the capacity view and the strategy view. The capacity position predicts a decrease of task-related performance whereas the strategy view presupposes an increase if the available strategies are adequate. The assumptions of both positions are tested using the paradigm of strategic priming. A group of 22 subjects receiving a negative mood induction were compared to 26 subjects receiving a neutral mood induction. Results clearly contradict the capacity view but favour the strategy position.