The question of whether nature or nurture has the greatest impact on determining how we differ as individual human beings is treated in a new study that finds that 49% of the average variation for human diseases and characteristics is based on genetics and 51% is due to environmental determinants.
The Huffington Post’s Carolyn Gregoire reports that as the debate continues over the power of nature versus nurture, University of California, Santa Barbara psychologists became interested in discovering if one or the other has more influence on a person’s intelligence.
“Scientists are probably just as split as they have always been on the nature vs. nurture issue,” John Protzko, a developmental psychologist at the university and the study’s lead author, said in a statement. “Almost all will agree that it is a mix of both; but that is largely where progress ends.”
Research has shown environmental interventions such as taking a nutritional supplement or having the opportunity to attend preschool are responsible for temporary gains in intelligence, after which nature takes over when intellect is shifted again.
The researchers, in a study to be published in the journal Intelligence in May, analyzed existing information on the ways a wide range of environmental interventions affected the intelligence of 985 children born with low birthweight.
These young ones experienced environments during their first three years that were intense and intellectually demanding. When the children were three years-old, their knowledge, fluid reasoning, quantitative reasoning, working memory, and visual-spacial processing were tested. The youngsters were tested again at the ages of five and eight.
The results showed that environmental interventions did boost intelligence, but the expansion was only passing, meaning the gains diminished over time. The team referred to this as the “fadeout effect.”
The scientists theorized that intelligence adjusts to meet a higher level of environmental requirements. When these demands ebb, the intellect goes back to its prior level. The report also suggested that high levels of intelligence at one age do not seem to result in high intellect at succeeding ages as psychologists had believed in years past. Still, intelligent interventions meant to enhance cognitive development are always helpful.
“I believe it is still a good thing to intervene and try to change the trajectory for these children,” Protzko said in a statement.
According to Julie Cohen, writing for The UC Santa Barbara Current, Protzko is also a postdoctoral scholar in the META (Memory, Emotion, Thought, Awareness) Lab in UCSB’s Department of Psychological & Brain Sciences. He said that general intelligence is not just about pushing scores around on a piece of paper. He explained that general intelligence reflects underlying cognitive capacities. IQ scores are a quantitative measure of intelligence.
Interventions for the kids were used to improve the adverse effects of being born with a low birth weight. At three, the children were given the Stanford-Binet Intelligence Scale as a baseline to measure their intelligence. The Stanford-Binet test is used to measure cognitive ability and intelligence and includes verbal and non-verbal questions, reports the Indo‑Asian News Service.
Some experts have thought that there is a causal connection, meaning intelligence at one age means the same intelligence at another age. However, Protzko explained:
“… my analysis starts to bring evidence to the idea that intelligence may not be the causal factor we suppose it to be from the correlation work — at least not in children.”