Dickens' research interests include unemployment, race and intelligence, and changes in IQ over time. For example, he co-authored a 2006 study with James Flynn showing that the black-white IQ gap in the United States had decreased in size by at least 25% between 1972 and 2002. He and Flynn had previously proposed a hypothesis for why IQ appears to be both highly heritable and significantly affected by the environment. Their hypothesis argued that individual's IQs are significantly affected by both genes and environment, but that people's environments change in response to their IQs.