Some exciting work has been done on individual differences in understanding, learning from experience, reasoning, problem-solving, and thinking abstractly — generally referred to as IQ. IQ scores predict school and long-term work success. These abilities are too often seen as something someone is born with but the last 15 years of research has been able to demonstrate that the environment that a child grow up in makes a huge difference. The recent work on how data is gathered and analyzed has been able to show that differences in homes and communities matter a great deal.

Some of the most exciting and compelling results, from my perspective, were completed in 1995 by Betty Hart and Todd Risley. The study is described in their book Meaningful Differences. Hart and Risley set out to understand the big differences between kids in different socioeconomic groups on school success so they looked very closely at the home environments of these kids. Their research team went into homes and recorded everything that was said to a child over a period of time. They found out that some very young children hear 30 million different words by the time they are 3 years old and some only 10 million words! The number of different words spoken to the child had a profound effect on differences in IQ by fourth grade. The take home message: talk to the baby!

Hart and Risley found something else: babies in homes with less economic stress were given 6 encouraging and positive statements from every corrective or critical statement. In economically stressed homes – impoverished—there were two corrective statements for every one supportive. These differences may be extremely important in children’s willingness to persist in difficult tasks. Other research teams have measured the overall enrichment of homes (e.g.,  books, adults reading to children, emotional warmth, trips to enriching events) and found these environmental characteristics to be very strongly tied to school performance.  Moreover, among people in cultures that believe that intelligence is the result of hard work and that everyone is obligated to do their best, we tend to find kids with stronger school achievement. Encourage the baby for working!

Currently researchers are working on understanding some of the ways that stress impacts cognitive development. For example, it seems that learning self-regulation (patience and being motivated to keep trying in the face of challenges) might have a very big impact on test performance and intelligence. Think about the marshmallow test that I talked about earlier. In that post, I linked to a video with some ways to use games to help your toddler learn better self-control and motivation with positive discipline. Help the child learn to wait and to persist!

Note: intelligence does not mean world famous inventions, business models, research programs for most of us. Being smart is really about finding a way to make the world work the best one can given the world the way it is. When children see themselves as able to persist and know how to persist they do better. When children are given access to the books and information and shown that it is valued they do better than children who are taught not to value it.

A final note on flawed research conclusions.

Fifteen years ago, The Bell Curve (Herrnstein & Murray, 1994) was published. The book received a great deal of popular press that did not discuss the flaws. The book was a substantial review of intelligence and included a significant amount of data but also drew a number of inflammatory conclusions about race and intelligence and the meaning of these differences that were based on faulty reasoning and  inadequate data analyses.  A representative group of psychologists critically evaluated the scientifically merits of the Bell Curve and the results of this review were published in the American Psychologist (Neisser, Boodon, Bouchard, et al., 1996). Neisser and colleagues summarized the current state of knowledge of what contributes to individual differences in intelligence and the meaning of these differences. One of the most important weaknesses was a lack of attention to the significance of environmental contributions to intelligence and an over-estimation of the role of genetic influences.

I hope today’s post helps you to be a smarter consumer of research.  There have been some really exciting advances in the study of intelligence.  Some of the results have helped us  to understand interactions between environments and genetics and differences between groups. Some studies have raised more questions for further study. Science is a dynamic process that is exciting and vulnerable to the limits of human biases.  We can overcome these biases to some degree by acknowledging them and by persisting in challenging our conclusions: Challenging and disproving makes science valuable not worthless.

Today’s post is from a paper by Richard Nisbett, Joshua Aronson, Clancy Blair, William Dickens, James Flynn, Diane Halpern, & Eric Turkheimer that was published in the American Psychologist (2012) Vol. 67 (2), ppg. 130 – 159).