NEW YORK (Reuters Health) - A new study shows that children consume more snack food - almost one third more than usual - when they eat in large groups.

"This observation makes sense in that people - and animals - perform behaviors 'more' or 'more robustly' when they are doing the behavior surrounded by others," Dr. Julie Lumeng who led the study told Reuters Health.

"This phenomenon called 'social facilitation' explains why we laugh more with the laugh track on sitcoms and drive faster on busier highways -- because we are surrounded by others doing the same thing," she explained. Studies have shown that animals, such as puppies, chickens and rats, all eat more when they are surrounded by other puppies, chickens and rats also eating. It's also been shown that adults eat more in social settings, compared to when they eat alone.

The current study, published this week in the Archives of Disease in Childhood, is the first to test this phenomenon in children.

Lumeng from the Center for Human Growth and Development at the University of Michigan, Ann Arbor, and colleagues studied the eating behavior of 54 children ages 2.5 to 6.5 while in a group of nine children or in a group of three children.

"These meals were videotaped, so we were able to closely examine their behaviors," Lumeng said.

When the allotted snack time was the same, children who ate in groups of nine ate about 30 percent more than children who ate in groups of three.

This effect seems to be fueled by increased arousal. Children ate more in the larger groups, Lumeng explained, at least partly because they started to eat more quickly after they sat down, ate faster, and socialized less.

"Their meals did not last longer. The children seemed to eat more because their eating was less calm and relaxed, and very subtly, perhaps a bit more frenzied in its pace," she said.

"The results suggest," according to Lumeng, "that if a child is overweight, or a parent is concerned that the child overeats, the parent may want to watch how much time the child spends eating in large group settings, as it is possible that eating in these settings may increase the amount that the child eats."

These findings, Lumeng added, provides more support for having family meals at home around the dinner table, as opposed to eating out at restaurants where one is likely surrounded by many other people simultaneously eating.