Role of early cognition/language in later language ability during childhood - A longitudinal comparison study

Many factors may influence early language development, but the precise impact of cognitive development remains unclear.

This study aims to explore how cognitive development contributes to language ability and to compare the explanatory value of early cognitive and language ability at 2;0 (years;months) on the language ability at 3;6 and at 5;0.

Sixty-one typically developing children were followed up. At 2;0, cognitive development was measured using the Bayley Scales of Infant and Toddler Development III, and language ability was measured using the Reynell Developmental Language Scales III. At 3;6 and 5;0, language ability was measured using the Boston Naming Test, the Finnish Test of Phonology, and the Finnish Morphology Test.

Cognitive development at 2;0 correlated significantly with language ability at 3;6 (r = 0.15-0.35, p = .01-0.24) but not at 5;0 (r = 0.12-0.25, p = .05-0.36). The associations between early and later language ability were clear at both age points (r = 0.41-0.69, p < .00). Explanatory value of cognitive development at 2;0 was 7-11 % (p = .02-0.07), while the respective values for later general language ability were 40-45 % (p < .00).

This longitudinal study provides novel comparison information on the role of early cognitive and language development in later language ability. Results suggest that language development is strongly based on early language ability during childhood, whereas the role of cognitive development seems less straightforward.