A new study suggests that the consistency of maternal care may be more important in raising children than the amount of affection shown by mothers (even rat mothers), and that exposure to different environments can significantly impact a child's development.

Dr. Akaysha Tang's research team at the University of New Mexico's psychology department and colleagues at Rockefeller University studied how early life experiences influence social skills and the ability to deal with stressful predicaments. The study was published July 30 in the online journal PLoS ONE.

In the study, Tang and colleagues used the promise of a chocolate reward to compare how different rat siblings behaved. Some infant rats were exposed to greater novelty by spending three minutes a day away from their homes; these novelty-exposed rats were able to outwit their competitors for chocolate more often than their shut-in siblings who remained at home all day. The novelty-exposed rats also displayed a decrease in the release of stress hormones into the bloodstream, suggesting they could adapt more quickly to stressful situations.

The study looked at rats that were 24 months of age — considered old age for a rat. The study consisted of only 60 minutes of different treatment, in the first three weeks of life, indicating that even very brief exposures to a novel environment during infancy can influence social ability over a lifetime.

Tang and colleagues also measured how much mother rats licked and groomed their pups (signaling attention and affection) after the novelty exposure and how consistently they provided this care. Surprisingly, the mother rats that delivered more care on average were inconsistent from day to day, leading the researchers to conclude that the novelty-exposed rats who could most easily adapt to stress had mothers that showed affection consistently but in lesser amounts.

The findings have significant implications for humans, standing in contrast to the commonly held view that large amounts of maternal care results in huge benefits for a child's development.