Babies and children learn by interacting with the environment they are raised in, although everybody knows a significant portion of their intelligence comes from their genes. One of the most interesting questions science ever asked is how much a baby’s experiences are relevant compared to inherited traits. Although in the last century we learned a lot about how children and babies learn and perceive the outside world, we still need to fully understand the role of environmental factors in shaping an infant’s intelligence.
A possible answer to the “nature versus nurture” debate has been provided by the postdoctoral scholar John Protzko, a psychologist at the University of California, Santa Barbara. In his study, published in the journal Intelligence, the psychologist from the META (Memory, Emotion, Thought, Awareness) Lab investigated the so-called “fadeout effect.” Dr. Protzko reviewed the results of an Infant Health and Development Program study of 985 children to determine if and how outside experiences may increase their intelligence levels. All the low-birth-weight babies lived in an intensely stimulating environment during the first three years of their lives due to the interventions required to improve their physical conditions.
The interventions did, in fact, affect the children’s intelligence that was measured with the Stanford-Binet Intelligence Scales several times during their life. At age three, children showed better performance than the average, showing that their intelligence was effectively raised by the environmental factors. However, at age five and eight, the improvements were no longer present. The benefits suffered from the fadeout effect, proving that even the most intensive intervention cannot last for more than two years if there’s no continuity.
Interestingly enough, Dr. Protzko also noticed that the whole intelligence causality theory may be, indeed, faulty. According to this theory, intelligence at one age may be the cause of improved intelligence at another subsequent age. So if a given individual is, for example, more intelligent than the average when he’s 15 years old, he will be more intelligent than the average adult as he grows up. However, results from Protzko’s work may suggest the opposite, at least in children. Similarly to the ability to adapt shown by muscles or many other organs, as soon as the environmental demands that require a higher intelligence are no longer present, intelligence returns to its original level. Any gains are not permanent if the environment does not keep stimulating the individual, and intelligence, just like strength or agility, may fade out over time.