Clark et al. focus on the likely drivers of the Flynn effect (sociocultural, educational, technological), and imply that it is not a single causal agent driving the upward climb in IQ scores but perhaps multiple causes with different onsets. Given, the authors' conception of intelligence in terms of underlying attentional and cognitive resources that are deployed to solve higher-level cognitive challenges, Ceci and Williams argue that the Flynn effect has not elevated actual intelligence, only provided useful tools to solve contemporary problems. Today, transnational comparisons of IQ scores reveal how social, economic, and educational policies affect children's IQ scores, often dramatically (Rindermann & Ceci, 2009). Yet, there is no evidence that these policies affect underlying intellectual ability.