Social facilitation of duration and size but not rate of the spontaneous meal intake of humans.

The amount eaten by humans in spontaneously ingested meals is positively correlated with the number of other people present. In order to investigate whether this social facilitation of eating was due to an increase in arousal, emotionality, hunger, or social interactions, analyses were performed on the data obtained from 82 adult humans. They were paid to maintain 7-day diaries of everything they ingested, when and where they ingested it, the number of other people present, and their subjective states of hunger, elation, and anxiety. The presence of other people was found to be associated with the duration of meals and not the rate of intake, whereas self-rated hunger was found to be associated with the rate of intake and not the duration of meals. Self-rated anxiety was not found to be associated with the number of people present, whereas self-rated elation was positively correlated with the presence of others. Multiple regression analyses suggested that the presence of other people facilitates intake and increases elation independently. It also suggested that social facilitation operates by independently increasing the size and the duration of meals and that it operates independently of the subjective state of the individual. These results contradict the predictions of increased arousal, increased hunger, and increased emotionality models but support attentional, disinhibitory, and time extension models of social facilitation.