Human intelligence relates to neural measures of cognitive map formation

Psychometric research on intelligence identifies latent factors underlying performance correlations across cognitive tasks, with one general factor explaining most variance and predicting life outcomes. Their biological basis is unresolved, particularly regarding the underlying neural information processing mechanisms. We tested whether interindividual differences in relational processing, supported by hippocampal cognitive maps, relate to fluid intelligence (g_f), an approximation of the general factor. Using standardized cognitive tests and functional magnetic resonance imaging (fMRI) of different mnemonic tasks, we demonstrate a positive correlation between g_f and map-like encoding of object-location associations learned piecemeal. Their representational geometry in the lower g_f range was less consistent with any two-dimensional arrangement, congruent with less relational integration at encoding. Intelligence was not related to non-relational hippocampal item memory, further supporting the specificity of our finding to relational rather than mnemonic components of hippocampal processing. These results provide empirical support for a link between neural mechanisms of relational reasoning and general cognitive performance.