The Effect of Plausible Versus Implausible Balance Scale Feedback on the Expectancies of 3-to 4-Year-Old Children

Previous studies (Case, 1985; Siegler, 1981) have shown that children under the age of 5 years have little understanding of balance scales when required to encode the influence of weight or distance from the fulcrum. More recently, however, Halford, Andrews, Dalton, Boag, and Zielinski (2002) noted that an understanding based on weight alone is present even in 2-year-olds. In all these experiments, weight was varied using multiple objects of the same weight. Consequently, the children's decisions could have been based upon visual features (size, number) without necessarily taking the weight into account. The present study investigated whether young children are able to correctly encode the relevance of weight in influencing the behavior of a balance scale. We studied how well 3- to 4-year-old children learn to use one of two different weights (of equal appearance) to tip the scale. In the plausible condition, the heavy weight produced the desired outcome. In the implausible condition, the light weight caused the scale to tip. Only 4-year-olds' performance differed between conditions by learning more effectively in the plausible than the implausible condition. Our results suggest that children younger than 4 years of age have not yet developed clear expectations of the role of weights on the movements of a balance scale.