It is sometimes said that while talking about politics the average person loses 15 IQ points. You could look for evidence that this effect persists with a classic priming experiment: people are randomly assigned to answer questions about either current political issues or something innocuous before taking an IQ test. See if the people who recently had politics on the brain did worse than those who didn’t.
This test may already have been done inadvertently by someone trying to figure out which political groups have higher IQ scores, since the same experiment could also provide evidence on that front.
Bonus: If the experiment finds the predicted effect, calculate what the lengthening US election cycle may be doing to average effective IQ (and therefore GDP, et c).
Pursuit of Truthiness 