Intellect is not that expensive: differential association of cultural and socio-economic factors with crystallized intelligence in a sample of Italian adolescents

Current theories of intelligence maintain that intellectual development is the expression of a strict interplay among different cognitive abilities and the environment. Yet, the environment in which the individual develops has often been reduced to a single measure in empirical research, which thus loses sight of its inherent multifaceted structure. This work stems from the need to grasp such multifaceted complexity, by differentiating the associations of cultural and socioeconomic factors with crystallized and fluid intelligence in adolescence. An updated and digitalized version of the Verbal task from the Primary Mental Abilities battery (PMA Verbal) was administered to a large group of Italian adolescents as a measure of crystallized intelligence. Item Response Theory confirmed the good psychometric properties of the test. The relationship among cognitive abilities and the environment was explored through a Network Analysis on measures of crystallized intelligence (PMA Verbal), fluid intelligence (Raven SPM) and various environmental dimensions (socioeconomic status, home possessions, books at home, reading habits). Network Analysis is particularly suited for highlighting the individual role of each variable within such a complex system. Our results illustrated a key role of books at home, which was positively connected to verbal abilities on the one hand and to reading habits on the other, whereas no relationship to fluid intelligence was found. Crucially, these findings were independent of socioeconomic status. This study indicates that a more detailed conceptualization of the environment provides a better understanding of how cognitive abilities develop.