New Delhi, Aug. 31: A set of never-before experiments has helped psychologists detect differences in brain activity that appear to suggest that infants and toddlers have a moral compass that allows them to distinguish altruistic from antisocial actions.

The studies, which measured the brain waves and behavioural responses of children aged 12 to 24 months, have revealed distinct patterns of brain activity underlying their perceptions of helpful, pro-social and harmful, antisocial behaviour.

They also suggest that the differences, seen in the frontal cortex region of the children's brains, are linked to their parents' value systems. The findings were published today in the journal Proceedings of the National Academy of Sciences.

"These novel and intriguing observations warrant further investigation to decipher what contributes to such parent-child transmission of values at such a young age," Jean Decety, professor of psychology at the University of Chicago who led the study, told The Telegraph.

"They may be based on either biological or socio-environmental influences, or more likely on a complex and dynamic interaction between the two," added Decety, who has been analysing the origins of altruism and pro-social behaviour.

Several behavioural studies over the past decade have suggested that babies can distinguish between "good" and "bad" actions.

Psychologist Kylie Hamlin at the University of British Columbia in Canada and her collaborators from institutions in the US showed in pioneering experiments five years ago that three-month-old infants demonstrate preferences for pro-social animated characters, acting in a helpful way towards others, over antisocial characters.

Another research group, lead by psychologist Celia Brownell at the University of Pittsburgh in the US, has found that children between the ages of 12 and 24 months comfort others in distress and are ready to give up favourite objects to soothe others.

The new study by Decety and his colleague Jason Cowell is the first to examine the underlying neurological mechanisms that appear to underpin this early ability of infants and toddlers to distinguish between good and bad behaviour.

The researchers examined electroencephalograph readings, tracked eye movements, and studied the behaviour of the children in the two experiments.

In one experiment, the children witnessed an animated character trying to climb a hill while another character approached either to help the first character in the climb --- a display of pro-social behaviour --- or to hinder the climb, displaying antisocial behaviour.

In the second experiment, the children watched animated characters performing pro-social acts such as sharing food or antisocial acts such as pushing other characters, and were later asked to pick tiny 3D models of the characters.

Infants and toddlers expressed preferential looking --- measured through average gaze times --- towards the pro-social characters rather than towards the beneficiary of the pro-social actions.

They exhibited a clear focus on the characters who helped others and appeared unmotivated to focus on the beneficiary of the positive actions.

In a reaching task, children who showed greater activity in the frontal cortex in response to the pro-social character were more likely to reach out for the 3D model of the pro-social character.

Those who had earlier displayed the opposite pattern of neural activity preferred to go for the antisocial character.

The children's preferences appeared to reflect their parents' sensitivity to justice and fairness.