Thinking is biological work and involves the allocation of cognitive resources. The aim of this study was to investigate the impact of fluid intelligence on the allocation of cognitive resources while one is processing low-level and high-level cognitive tasks. Individuals with high versus average fluid intelligence performed low-level choice reaction time tasks and high-level geometric analogy tasks. We combined behavioral measures to examine speed and accuracy of processing with pupillary measures that indicate resource allocation. Individuals with high fluid intelligence processed the low-level choice reaction time tasks faster than normal controls. The task-evoked pupillary responses did not differ between groups. Furthermore, individuals with high fluid intelligence processed the high-level geometric analogies faster, more accurately, and showed greater pupil dilations than normal controls. This was only true, however, for the most difficult analogy tasks. In addition, individuals with high fluid intelligence showed greater preexperimental pupil baseline diameters than normal controls. These results indicate that individuals with high fluid intelligence have more resources available and thus can solve more demanding tasks. Moreover, high fluid intelligence appears to be accompanied by more task-free exploration.

Individuals scoring higher in tests of general cognitive abilities tend to perform better on novel and familiar mathematical tasks. It has been scarcely investigated how this superior mathematical performance relates to the amount of cognitive resources that is invested to solve a given task. In this study we propose that, on novel tasks, individuals with high cognitive abilities outperform less able individuals, because they allocate a higher amount of resources. On familiar tasks, however, individuals with higher abilities profit from more efficient processes compared to individuals of lower cognitive abilities. We tested this hypothesis by administering to 11th graders a geometric analogy task not practiced at school and an algebraic transformation task comprising operations that are routinely required during mathematical courses. General cognitive abilities were measured with Ravens Advanced Progressive matrices (fluid intelligence), the d2 (focused attention) and KAI-N (working memory capacity). Resource allocation was measured by assessing pupil diameter during the problem-solving process. Performance on both the analogy and the algebra task was correlated with general cognitive abilities, especially fluid intelligence. In line with our assumptions, a positive correlation between fluid intelligence and resource allocation was observed in the novel geometric analogy task, whereas the correlation was not significant in the more familiar algebra task.

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This study investigates the relationship of reasoning and gesture production in individuals differing in fluid and crystallized intelligence. It combines measures of speed and accuracy of processing geometric analogies with analyses of spontaneous hand gestures that accompanied young adults' subsequent explanations of how they solved the geometric analogy task. Individuals with superior fluid intelligence processed the analogies more efficiently than participants with average fluid intelligence. Additionally, they accompanied their subsequent explanations with more gestures expressing movement in nonegocentric perspective. Furthermore, gesturing (but not speaking) about the most relevant aspect of the task was related to higher fluid intelligence. Within the gestures-as-simulated action framework, the results suggest that i ndividuals with superior fluid intelligence engage more in mental simulation during visual imagery than those with average fluid intelligence. The findings stress the relationship between gesture production and general cognition, such as fluid intelligence, rather than its relationship to language. The role of gesture production in thinking and learning processes is discussed.