Reaction Times and IQ

The research claiming that there's been a decline in IQ in the past century was partly based on the theory that fast reaction times are correlated with higher IQ. I find that a bit hard to believe. After all, as William M. Briggs said:

… if this research were true, we should hang out by the Whack-A-Mole to discover future Nobel Prize winners.

I'd like to know what the sample sizes were to obtain such a bizarre conclusion. Psychology research is notorious for small sample sizes (a recent example can be found here) and a lack of objective standards. On the other hand, there just might be a correlation … if being hungover and sleep-deprived causes both slow reaction times and lower IQ.