A new article, "Studying Intellectual Outliers: Are There Sex Differences, and Are the Smart Getting Smarter?," in Current Directions of Psychological Science by a trio of Duke University researchers looks at what is happening to IQ and math ability scores at the highest end of the IQ distribution—the top 5 and to 0.01 percent, respectively. About three decades ago, New Zealand political scientist James Flynn found that average IQ scores were increasing at a rate of 0.33 points per year. The Duke researchers find that IQ scores at the high end are basically increasing in line with the overall general trend.
The researchers also wanted to see if there were sex differences in math and verbal scores. An earlier study that looked at the students who scored in the top 0.01 percent on SAT-Math found the male-to-female ratio was 13.5 to 1. Their data finds that that ratio shrank to 4 to 1 and has remained more or less stable for the past two decades. They conclude:
The fact that we continue to find sex differences in math ability within the very smartest group means that sex differences in math ability are likely part of the explanation for female underrepresentation in high-level math and science careers.
They stress that math ability is a small part of the explanation. Looking again at the top 0.01 percent on the verbal tests they find:
These ratios primarily favored females, ranging between one and two females for every male, and like the gender ratios for math ability scores, they also appear to have been stable across time.
With regard to overall IQ score trends in the top of the distribution, they find:
Using multiple measures from the SAT, ACT, and EXPLORE tests, we examined whether the Flynn effect occurred for the intellectual outliers (i.e., the top 5% of scorers). Overall, the effect appeared to be concentrated on the measures of math (or nonverbal) ability, with small gains or no gains on the other measures. The gains on these measures of math ability (amounting to an increase of 0.33 IQ points per year) are similar to the average rate of gain found in studies focusing on the general distribution; therefore, this right-tail finding links directly with the broader literature on the general population…. These findings demonstrate for the first time that scores among the entire distribution (including the right tail) have risen at a relatively constant rate. The Flynn effect may also explain why an increased number of gifted students has been identified in recent years: Gifted programs often have cutoff scores that do not change over time, which may correspondingly lead to a higher proportion of students attaining that cutoff score.
What is boosting IQ scores among the smartest? The Duke researchers speculate:
We think our findings suggest that enhanced cognitive stimulation may play a role in the right-tail gains. For example, the rise of digital culture and video games may be involved.
Play video games—it's for the kids!
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