ABSTRACT
When a layperson thinks of individual differences in reasoning they think of IQ tests. It is quite natural that this is their primary association, because IQ tests are among the most publicized products of psychological research. This association is not entirely inaccurate either, because intelligence is correlated with performance on a host of reasoning tasks (Carroll, 1993; Deary, 2000, 2001; Flynn, 2007; Hunt, 2011; Lubinski, 2004). Nonetheless, a major theme of this chapter will be that certain very important classes of individual differences in thinking are ignored if only intelligence-related variance is the primary focus. A number of these ignored classes of individual differences are those relating to rational thought.
