Sixty-four 7-year-olds were introduced to the faraway planet "Glinhondo" and its alien occupants. The children were then split into four groups and shown pictures of 12 different scenarios, each accompanied by a short spoken description. The scenarios involved several aliens engaging in behaviours directed at their own bodies (e.g. covering their heads with sticks) or at the environment (e.g. sprinkling blue water into a big puddle). After seeing each scenario, the kids had to say whether the depicted behaviour was "wrong" or if it was "OK".

Children in the "disgust" condition viewed the pictures in a room sprayed with the stinky but harmless joke-shop product "Liquid ASS", and the description of the scenarios also highlighted that the alien behaviours were disgusting. Children in the "unnatural" condition viewed the scenarios in a fresh room, but they saw pictures in which only a minority of aliens performed the behaviours and the description highlighted that what they were doing was "unnatural". Kids in a third group experienced a combination of the disgust and unnaturalness - the room stank and it was a minority of aliens performing the behaviour, which was described as unnatural. Finally, some of the kids formed a control group - the room was fresh, all the aliens performed the behaviours and the description merely said that what they were doing was boring.

Children in the combined disgust and unnaturalness condition judged 65 per cent of alien behaviours as "wrong", compared with just 19 per cent of behaviours judged that way by the control group. "This demonstrates that moral acquisition can occur rapidly and in the absence of direct experience with moralised behaviour," the researchers said. "This also speaks against the idea that the primary mechanism guiding moral acquisition is children's active reasoning about harmful or unjust consequences."

The children in the disgust-only or the unnatural-only conditions also judged more alien behaviours as wrong, compared with kids in the control condition, but in both cases they tended to answer "wrong" about half the time, so there's a possibility they were just alternating their answers at random.

The findings show how visceral feelings of disgust combine with intellectual thoughts about what's "natural" to invoke in children a sense of moral wrongness. Another finding was that environmentally directed actions were more often judged as wrong than self-directed actions. "Ultimately, the degree of plasticity inherent within a young child’s moral repertoire is a crucial area of future exploration, and one that is currently under explored," Rottman and Kelemen concluded. "The implications of such research will be substantial, promising to answer fundamental questions about the horizons of our moral nature."

   Rottman J, and Kelemen D (2012). Aliens behaving badly: Children's acquisition of novel purity-based morals. Cognition, 124 (3), 356-60 PMID: 

From BPS Research Digest