Why are negative behaviours likely to be immediately invoked traits? The effects of valence and frequency on spontaneous trait inferences

People make trait inferences immediately when observing others’ behaviours. Previous studies reported that this spontaneous trait inference (STI) occurs more strongly from negative behaviours than from positive behaviours. However, what is responsible for this negativity bias in STI is unclear. In this study, two experiments investigated the effects of valence (an event's affective positivity or negativity) and frequency (how frequently the behaviour is observed in everyday life) on the occurrence of STI using an adapted version of a savings-in-relearning paradigm. Experiment 1 revealed that only valence affected the frequent occurrence of STI. In addition, the instructions to suppress impression formation or to focus attention on an actor's face made no difference to the results. In Experiment 2, the negativity bias in STIs was shown a week after exposure to the behavioural stimuli. These results suggest that the negativity bias in STIs occurs robustly, and the negative valence of observed behaviour is mostly responsible for the negativity bias in STI. The importance of immediate categorization of negative stimuli is discussed in terms of ecological priority.