We are usually eager to assist people who have helped us in the past. These reciprocal relationships are an important part of adult interactions and foster cooperation in society. New findings, reported in Psychological Science, a journal of the Association for Psychological Science, suggest that this reciprocal behavior may have early beginnings and can be demonstrated in children as young as 21-months-old.

Psychological scientists Kristen A. Dunfield and Valerie A. Kuhlmeier from Queen's University in Canada wanted to examine the specificity of infants' helping behavior — that is, if they are likelier to help one person over another. In this experiment, were introduced to two actresses who offered, but failed to provide, them with a new toy. One of the actresses was unable to give the infant a toy: she offered the toy by placing it on the edge of a slanted table, and watched in surprise as it rolled away. The second actress was unwilling to give the infant the toy: she showed them the toy and then took it away. Then, when the actresses were sitting next to each other, facing the infant, the experimenter placed a toy on the edge of the table, so that it fell off. Both of the actresses reached for the toy (which was out of arms' reach) and the experimenters watched to see what the infant would do.

Infants were more likely to pick up a dropped toy and hand it to an actress who was previously willing, although unable, to give them a new toy than to hand the toy to an actress who was previously unwilling to give them a new toy. These results suggest that infants were selectively helping the actress who had earlier acted with good intentions towards them.

Next, the researchers wanted to see if the infants made their choice based on the positive intentions of the actresses or if a successful outcome can trump good intentions. The set-up was similar to the first experiment, except the unwilling actress was replaced by one who was successful in giving the toy to the infant. The infants in this experiment were equally likely to hand over the toy to each actress — a successful outcome was not enough to encourage selective helping.

These results suggest that by 21 months of age, infants display selective helping behavior and this behavior is based on their previous interactions with others. Furthermore, the intentions of individuals they are interacting with, even more than actual outcome, play a large role in determining infants' helping behavior. The researchers conclude that these findings indicate "that some of the characteristics of the rich reciprocal relationships observed in adults are in place in infancy."