Effects of food variety on expected satiation: Evidence for a ‘perceived volume’ heuristic

Recently it has become clear that people use prior experience with a food to estimate the extent to which it will deliver fullness. These ‘expected satiation’ judgments may be straightforward when only one meal component needs to be considered but it remains unclear how people estimate prospective satiation when a meal comprises multiple meal items. For example, how do we estimate how filling a plate of buffet food is likely to be? Based on a broader understanding of decision-making, we sought to explore whether individuals simplify the task by using a heuristic, or ‘cognitive shortcut.’ Specifically, we hypothesised that under conditions of increasing food variability, we base judgments of expected satiation on the perceived volume of food(s) rather than on prior experience. Participants (N = 68) were shown images of buffet food. On each trial, the number of different types of food ranged from one to six. For each image they were asked to provide an estimate of expected satiation and perceived volume. As predicted, when food variability was low, significant differences were observed between responses based on perceived volume and those based on expected satiation. By contrast, when food variability was high, these judgments coincided. Together, these data indicate that when multiple food items are available then perceived volume plays an important role in portion-size selection. This offers a new perspective on our understanding of ‘food variability’ and the effect this has on overconsumption.