How Small Groups Sap Intelligence — Especially in Women

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There’s a reason the term “designed by committee” is not a compliment. A new study suggests that the dynamics of being in a small group can reduce some people’s IQ performance, and the decline is far more pronounced in women than in men.

Researchers studied 68 people, recruited at the Texas Medical Center in Houston and the California Institute of Technology. Most of the participants had high IQs: the average was 126 (normal is 100). The study volunteers were introduced to one another, then split up into groups of five and tested.

First, participants each took a written IQ test, and were not given any information about the results. Then, they answered more IQ test questions on a computer — but this time, after each question, they were told how their answers ranked them within the group. Two members of each group also had their brains scanned with functional magnetic resonance imaging while completing this part of the research.

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At first, everyone’s performance declined when they received information about rankings. “You may joke about how committee meetings make you feel brain dead, but our findings suggest that they may make you act brain dead as well,” said lead researcher Read Montague, a neuroscientist at Virginia Tech, in a statement.

Some people were more vulnerable than others to the mental interference caused by social status information. Ten of the 13 people who performed best on the IQ test were men, while 11 of the worst performers were women. The researchers had not expected this sharp gender difference and are unsure how to account for it.

One possible explanation, based on prior research, might be that women were influenced by information that could confirm negative stereotypes about gender, which caused stress and reduced their performance. Some studies have found that cues about social stereotypes — like having to write one’s gender on a test before taking it — can lower performance. (Interestingly, on math tests, Asian women do better when they’re reminded of being Asian, and worse when cued to think of their female gender.)

The brain scanning data in the current study offered some support for the idea that stress played a role. Researchers found that people who regained their ability to perform at their previous capacity showed less activity in their amygdala, a region that is activated by stress and anxiety, compared with those who didn’t. The high performers also showed increased activity in the right lateral prefrontal cortex (r-LPFC), an area linked to working memory, which can shut down under stress. This group may have had greater control over their amygdala and their anxiety via the r-LPFC.

The study could not determine whether these differences in brain activity seen between the high- and low-performing groups could be explained by gender, rather than stress, however.

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Researchers also found, not unexpectedly, that the nucleus accumbens — a brain region associated with pleasure — was activated when people learned that they ranked high within the group. However, these brain responses depended on their expectations. After answering a question incorrectly, people feared that their rank would fall — if it didn’t, the nucleus accumbens lit up because they were happily surprised that they did better than expected.

In contrast, if they got a question right but still fell in ranking, the region showed deactivation due to disappointment. Getting a question right and rising in rank increased nucleus accumbens signaling, but not as much as getting it wrong and still rising in status. This adds to research suggesting that the nucleus accumbens specializes in reward prediction. While it’s happy to receive a predicted reward, it’s even happier to get an unpredicted one.

The authors note that their study has wide-ranging implications, given the prevalence of situations in which people are made aware of their social standing but must work together in groups. From business meetings and government committees to cocktail parties and jury deliberations, these settings are common — and this study suggests that women’s intelligence may be particularly likely to be stifled by them.

To raise the IQ of groups, perhaps we need to increase feelings of equality.

The research was published in the journal Philosophical Transactions of the Royal Society B.

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Maia Szalavitz is a health writer at Find her on Twitter at @maiasz. You can also continue the discussion on TIME Healthland’s Facebook page and on Twitter at @TIMEHealthland.