Children who grow up in an orphanage are likely to have lower intelligence quotient (IQ) than children who grow up in foster families, a new study shows.
Although psychologists have long suspected that growing up in an institution like an orphanage stunts children's mental development, they never had direct evidence to back up their view.
In the latest experiment conducted in Romania, scientists compared the effects of foster care with those of institutional child rearing.
They found that toddlers placed in foster families developed significantly higher IQs by the time they reached four years of age, on an average, than peers who spent those years in an orphanage, reported the online edition of The New York Times.
The difference was large, eight points, and the study found that the earlier children joined a foster family, the better they did.
Children who moved from institutional care to families after they attained two years made a few gains on average, though the experience varied from child to child.
Both groups, however, had significantly lower IQs than a comparison group of children raised by their biological families.
"Institutions and environments vary enormously across the world and within countries," Charles A Nelson III of Harvard and Children's Hospital in Boston said.
"But I think these findings generalise too many situations, from kids in institutions to those in abusive households and even bad foster care arrangements," Nelson said.
"The evidence seems to suggests that for humans, we need a lot of responsive care giving, an adult who recognises our distinct cry, knows when we're hungry or in pain, and gives us the opportunity to crawl around and handle different things safely, when we're ready," said Seth Pollak, a psychologist at the University of Wisconsin, who was not involved in the research.