Study: Babies Know What's Right and Wrong Within Two Years

"He just doesn't know better" may no longer be a good excuse for poor behavior during the terrible twos or later toddler years anymore. A new study is saying babies begin to know the difference of right and wrong, fair and unfair as young as 15 months old.

The research out of the University of Washington also gained insight into the development of "sharing" personalities.

"These norms of fairness and altruism are more rapidly acquired than we thought," study researcher Jessica Sommerville, of the University of Washington, said in a statement. "These results also show a connection between fairness and altruism in infants, such that babies who were more sensitive to the fair distribution of food were also more likely to share their preferred toy."

Unlike previous studies that showed 2 year olds being altruistic by helping others and between the ages of 6 or 7 understanding fairness, Live Science reports this research is revealing these sense as a much earlier age.

How were researchers able to determine this? Not by putting a bunch of 15-month-olds in a room with a bowl of Cheerios but by watching their expressions when they saw just and unjust behavior. When a baby is surprised by something, he or she will stare at it longer. Researchers had babies watch a video of an adult dividing crackers or milk between two other adults. What they found was that babies watched footage of unequal sharing with more intensity.

“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.

The researchers also tested sharing ability by giving the toddler two toys and asking them to share one. A third of the time, the child handed over the toy they were playing with, a third provided the toy they had not chosen to play with and the final third didn't give up either toy.

Comparing these two tests, the researchers found that 92 percent of the babies who shared their preferred toy – called “altruistic sharers” – spent more time looking at the unequal distributions of food. While 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. Meanwhile, the selfish sharers showed an almost opposite effect, she said.

The researchers are now looking into whether these attributes are innate or learned from parents.