Monday, October 12, 2009

IQ and negative emotionality: The GSS asked respondents four questions: How many days out of the past week were you: 1) angry, 2) anxious and tense, 3) sad, and 4) fearful that something would happen to you? Answers were all intercorrelated. I converted them to z scores and summed them to create an index of negative emotionality (also called neuroticism). The alpha coefficient is .68.

Here are the mean scores for smart people (those scoring 9 or 10 on the vocabulary quiz) and for everyone else:

Mean negative emotionality (N = 935)

Smart group .62
Everyone else -.11

The difference between the two groups is significant at the 95% confidence level. The gap is 26% of one standard deviation which indicates a small difference.

The results seem right, but I am not sure why smart people are more neurotic. Perhaps a reader steeped in the science has an idea.

It does seem like there is a calmness that comes with not thinking about things much.


  1. I'm not steeped in the science, but I'll answer.

    Smart peopele are more neurotic because they're generally more aware of everything going on. They're constantly thinking and processing not only the stuff happening around them, but also current events, something they were trying to solve, some piece of advice they just got, etc.

    The intelligent mind is an active mind.

  2. I know there is evidence that neurotics are sensitive to aversive stimuli. Perhaps IQ sharpens this.

  3. Are you sure this index is the right approach, it seems to go against the correlations I've seen Jason Malloy observe on IQ and depression. Then again, I'm not that familiar with the key distinctions that distinguish the neurotic from the depressive in the personality research.

    One such comment here on Magan:

    Yet the myth of a link between high IQ and mental illness, or at least a disturbed personality, lives on, as The New Yorker article illustrates"

    Recently I checked the General Social Survey to find the relationship between IQ, mental illness, and 19 different affective states. There was an inverse relationship between IQ and depression (-.13), and having had a mental illness (-.18), and the duration and severity of that illness (-.31).

    On the other hand, mental illness, disturbed personality, and IQ were positively correlated for Jews. This could be due to 'overclocking'.

    So, if true, this might explain persistent media suspicions they are related in this way.

  4. quimbus: The two sets of results are not incompatible. My finding was very specific: the smartest group, compared to dumb, average, and somewhat smart combined, more frequently experiences negative emotions. I'm looking at the normal range of emotions, while the correlations you reported estimate a linear relationship across all categories, and concern mental illness. The relationship I reported is weak, as are those you posted. Don't intepret my finding to suggest that smart people are more likely to be mentally ill.


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