What transient factors affect performance on IQ tests?

Question

While performance on intelligence tests aim to measure an underlying relatively stable trait, there are presumably a range of transient factors that could temporarily lower or possibly even raise scores on such tests.

Possible factors might be: alcohol, sleep deprivation, mood, test taking anxiety, etc.

• Are there any studies so far that have assessed the degree to which such transient factors can influence performance on intelligence tests?
• Do such studies suggest such affects depend on other factors such as gender, personality, and presence/absence of ADD/Asperger's?

Answer 1

I had a course which was about IQ; I never read an article about it, so I can't quote studies (I can look up the references if you like).

There are indeed a lot of factors that can influence ones score on an IQ test. These are some transient factors that came to my mind:

• The setting: was the test taken at home, at school, at a totally unfamiliar place? Test scores tend to be higher when a child can take it at home.
• The part of the day: was the test taken in the morning, in the afternoon, or in the evening? I think (I should look this up) that scores tend to be lower if IQ tests are taken in the evening. Perhaps if you're a morning type, you're better in the morning than 'evening people', who are better in the afternoon than in the morning. But this is speculation (I know I've read something about it, but I can't seem to find it now).
• Motivation/Attention: this really can play a big role in the results. That's why good tests (e.g. the WISC) have a zone for remarks. Children with ADHD score better when they are given more pauses during the examination.
• Hormones: there is some evidence that there's a hormonal influence (testosteron, estrogen, congenital adrenal hyperplasia).
• Test taking anxiety: this can indeed influence the score negatively. It's important that the test leader says 'good job' or something like that. Normally, this isn't according to the guidelines of the test, but it's acceptable here, since you would underestimate the ability.

Answer 2

Here are two transient factors I know (but there definitely are more!):

• The color red (either presented as a color, or as a word) induces an avoidance motivational state, leading to an impaired IQ test performance [1][2]
• Stereotype threat: Inducing a negative stereotype of a group (e.g.: Women are bad at math) causes members of this group actually to perform worse. This works with gender, race, age, etc. [3][4]

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[1]: Elliot, A. J., Maier, M. A., Moller, A., Friedman, R., & Meinhardt, J. (2007). Color and psychological functioning: The effect of red on performance in achievement contexts. Journal of Experimental Psychology: General, 136, 154-168.

[2]: Maier, M. A., Elliot, A. J., & Lichtenfeld, S. (2008). Nonconscious avoidance motivation mediates the negative effect of red on intellectual performance. Personality and Social Psychology Bulletin, 34, 1530-1540.

[3]: Gerstenberg, F., & Imhoff, R. (in press). 'Women are Bad at Math, but I‘m Not, am I?’Fragile Mathematical Self‐concept Predicts Vulnerability to a Stereotype Threat Effect on Mathematical Performance. European Journal of Personality.

[4]: Smith, J. L. (2004). Understanding the process of stereotype threat: A review of mediational variables and new performance goal directions. Educational Psychology Review, 16, 177-206. doi:10.1023/B:EDPR.0000034020.20317.89