Surely one of the most charming sights is of an adult struggling to reach an object, only for a toddler to pick up that object and hand it to the adult, as research has shown they so often will. Psychologists think such ingrained altruism has evolved as a consequence of our species' dependence on group living for survival. Supporting this account, Harriet Over and Malinda Carpenter have shown that subtle exposure to the sight of two apparently companionable dolls, stood side by side, is enough to increase the likelihood that an 18-month-old will help an adult pick up some dropped sticks.
Sixty 18-month-old infants were shown eight photos of household objects, such as teapots, books or shoes. Crucially, infants were divided into four groups, with each group shown one of four versions of these photos. One "affiliated" version featured in the background two dolls standing together side by side; another version featured a doll in the background on its own; the third version featured two dolls facing away from each other; and the final version merely had toy bricks in the background.
After they'd been shown these photos, another experimenter walked over to the infants and dropped a bundle of sticks on route. Amazingly, the infants who'd seen the photos with the companionable dolls in the background were three times as likely as the other infants to help the experimenter by spontaneously picking up one or more sticks and handing it to the experimenter.
Further analysis showed it's not that the infants who'd seen the photos with companionable dolls were caused to be in a better mood, nor that they spent longer looking at the photos, than the other infants. Rather, according to the researchers, "the connections between affiliation to the group and prosocial behaviour are ... so fundamental that, even in infancy, a mere hint of affiliation is sufficient to increase helping."
Over and Carpenter said their finding has important implications for research - paving the way for future investigations of other non-verbal social influences on infants' behaviour - and also for real life. "Our data suggest that surprisingly subtle changes to our social environment may promote prosocial behaviour in our children."
Over, H., & Carpenter, M. (2009). Eighteen-Month-Old Infants Show Increased Helping Following Priming With Affiliation. Psychological Science, 20 (10), 1189-1193 DOI: 10.1111/j.1467-9280.2009.02419.x