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UW Study: Children as Young as 15 Months Show Sense of Fairness

Parents may think a sense of fairness in children emerges when “That’s not fair!” becomes their child’s favorite saying. But a new study out of the University of Washington suggests that babies as young as 15 months old have a sense of fairness and sharing.

The study, led by Jessica Sommerville, Ph.D., a University of Washington associate professor of psychology, tested 15-month-old babies to determine if they exhibited any signs of fairness and altruism, measured by an ability to share.

“Our findings show that these norms of fairness and altruism are more rapidly acquired than we thought,” Sommerville said.

Findings of the study were published online in the journal PLoS ONE this week. The co-author is Marco Schmidt, a doctoral student at the Max Planck Institute for Evolutionary Anthropology.

Previous studies have shown that 2-year-old children can help others – considered a measure of altruism – and that at around age 6 or 7 they display a sense of fairness. Sommerville, who is an expert in early childhood development, created her study to test her theory that these qualities emerge at younger ages. Forty-seven babies were tested individually.

To gauge whether young children have a sense of fairness, a 15-month-old baby sat on his or her parent’s lap and watched two short videos of people acting out a sharing task. In one video, a person distributed crackers from a bowl to two other people. The food was distributed twice – once with the crackers being distributed equally, and a second time with one recipient getting more crackers than the other.

The second movie had the same basic plot, but a pitcher of milk was divvied up instead of crackers.

The experimenters measured the amount of time the babies paid attention to each segment as they watched the distribution of the crackers and milk. According to a phenomenon called “violation of expectancy,” babies pay more attention when they are surprised, and the researchers found that babies spent more time looking if one recipient got more food than the other.

“The infants expected an equal and fair distribution of food, and they were surprised to see one person given more crackers or milk than the other,” Sommerville said.

To see if the babies’ sense of fairness related to their own willingness to share, the researchers did a second task in which a baby could choose between two toys: a simple LEGO block or a more elaborate LEGO doll. Whichever toy the baby chose, the researchers labeled it as the infant’s preferred toy.

Then an experimenter, whom the babies had not seen before, gestured toward the toys and asked, “Can I have one?” In response, one third of the infants shared their preferred toy and another third shared their non-preferred toy. The other third of infants did not share either toy, which might be because they were nervous around a stranger or were unmotivated to share.

Researchers then compared the toy-sharing task and the food-distribution task results and found a correlation between babies who were most sensitive to the unfairness of unequal food distribution and those who were labeled “altruistic sharers,” meaning they shared their preferred toy. Ninety-two percent of the “altruistic sharers” spent more time looking at the unequal distributions of food. In contrast, 86 percent of the babies who shared their less-preferred toy, the “selfish sharers,” were more surprised, and paid more attention, when there was a fair division of food.

“The altruistic sharers were really sensitive to the violation of fairness in the food task,” Sommerville said.

Does this mean that fairness and altruism are due to nature, or can these qualities be nurtured? Sommerville’s research team is investigating this question now, looking at how parents’ values and beliefs alter an infant’s development.

“It’s likely that infants pick up on these norms in a nonverbal way, by observing how people treat each other,” Sommerville said.

About the Author

Ruth Schubert