The science of intelligence has just added another item to a long list of biological phenomena correlated with IQ.
The journal Intelligence published this month a study which found that the ability to correctly identify two targets--letters of particular colors--out of a rapid stream of distractor letters is moderately correlated with IQ (r = .43) as measured by the Standard Progressive Matrices. This ability is called "attentional blink" and is thought to be connected to perceptual speed and working memory capacity.
The results of the study are consistent with Arthur Jensen's theory that intelligence is about mental speed. If you can process data more quickly, you are better able to successfully process complex information.
This type of research reminds me how ignorant liberals are about the basics of IQ science. They claim that IQ is just a measure of culture or social class, as if wealthier people are magically better at identifying letters out of a rapid stream.