Effects of social interaction, physical environment and food choice freedom on consumption in a meal-testing environment.

Consumption of pizza, salad and iced tea was assessed in four separate tests at a central location. Three aspects of context were added in successive tests-social interaction during consumption, the physical environment in which the food was consumed and choice among foods-so that the fourth test had all effects present. The proportion consumed averaged from 79 to 82% of the food presented and increased significantly in the presence of one or more of the context manipulations.