Thanksgiving tip: Portion size affects consumption

Psychologists say their research demonstrates the power of what's called "unit bias," the sense that a particular portion of food is appropriate.

"In terms of food, unit bias applies to what people think is the appropriate amount to consume, and it shows why smaller portion sizes can be just as satisfying," said graduate student Andrew Geier, the study's lead author. "A 12-ounce can of soda and a 24-ounce bottle are both seen as single units. But be careful, the 24-ounce bottle, though viewed as one unit, is actually more than two and a half servings of soda.

"We have a culturally enforced 'consumption norm,' which promotes both the tendency to complete eating a unit and the idea that a single unit is the proper amount to eat," he said.

The researchers believe a better understanding of unit bias will aid in studying the psychology of obesity.

The research is to be published in the journal Psychological Science.

Copyright 2005 by United Press International