The human brain may be wired to sympathize with the underdog. Even if the underdog is a yellow square being chased by a blue circle, and the brain has been checking out the outside world for only 10 months.

A Japanese research team found that 16 of 20 infants reached for the pursued yellow square rather than the aggressive blue ball as the ball bumped the square seven times, then smashed it.

Twenty other infants observed the objects moving independently without touching, with nine of them reaching for the persecuted square, according to the study, published in the online journal PLOS ONE.

The experiments hint at a very early cognitive ability to sense and respond to aggression with preference for the “victim,” a building block for sympathetic behavior that is a core element of social, cooperative animals.


The appearance of a preference for the victim at such a young stage is notable, the researchers said, given that infants of that age have not fully developed a firm differentiation between themselves and others.

Earlier research has shown that newborns are susceptible to “contagious” crying -- erupting into tears at the sight and sounds of another crying infant. Toddlers begin to show clear sympathetic behavior toward others at 18 months, and will comfort the underdog by age 2. The researchers at Kyoto University and Tyohashi University of Technology were trying to find out what happens between those ages.

There was a bit of a conundrum: Eye motion measurements did not show a preference for either object among infants watching either interaction, even though the reaching measurement clearly showed a preference for the underdog. One possible explanation could be that infants also may be looking longer at the aggressor because they are assessing threat, the researchers suggested.

All 40 subjects had been tested for any pretrial preference between the objects, either on screen or in person. Eight other infants were eliminated from the test for being too fussy or uninterested. Factors that could influence preference, such as speed, trajectory and deformation of the objects, also were held constant.


Researchers next addressed whether the infants reached for the victim only out of desire to avoid the aggressor. Was it self-preservation over sympathy?

Researchers repeated the trials with a third, “neutral” object -- a red cylinder that did not interact with the other two. How would the infants respond to a choice between a victim and bystander? How about between an aggressor and bystander?

Infants strongly preferred the neutral over the aggressor, and preferred the victim over the neutral.

The responses seem to show the infant brain making abstract evaluations based on previously observed actions of third parties that displayed no emotion -- the yellow box was not crying or behaving in a distressed way. Emotional contagion, such as sympathetic crying, can’t explain the choices, the researchers said.


Yet the infants did not display any discernible distress or concern, either -- just a preference.

So, was this an example of sympathy? Researchers suggest it was, though perhaps not in its full-fledged form. At a minimum, they say, these infants displayed the ability to ascribe a goal to an agent (in this case geometric objects), establish causation and place a negative valuation on aggression.

Combining this type of experiment with measures of brain activity, researchers suggested, could offer a clue to a preference for the underdog over the aggressor.

Because these 10-month-olds aren’t telling.