The unique contribution of working memory, inhibition, cognitive flexibility, and intelligence to reading comprehension and reading speed

There are several studies showing that executive functions such as working memory, inhibition, and cognitive flexibility are related to reading abilities. However, most of these studies did not simultaneously take different executive functions and intelligence into account. Therefore, the aim of our study was to investigate if working memory, inhibition, cognitive flexibility, and fluid intelligence uniquely contribute to reading. Furthermore, we tested the hypothesis that reading comprehension and reading speed are correlated but separable reading abilities with different relations to other cognitive functions. To test this assumption, we examined if executive functions and fluid intelligence unequally relate to reading comprehension and reading speed. A total of 186 school children (mean age = 9.31 years) participated in our study and performed a complex span task (working memory), task switching (cognitive flexibility), a stroop-like task (inhibition), raven matrices (fluid intelligence), a reading speed task and three reading comprehension tasks. Structural equation modeling (SEM) showed that working memory, inhibition, cognitive flexibility and fluid intelligence differently contributed to reading speed and reading comprehension. Working memory, inhibition and fluid intelligence were related to reading speed, indicating that a higher working memory capacity, better inhibitory abilities and higher fluid intelligence were associated with higher reading speed. Moreover, cognitive flexibility and fluid intelligence were related to reading comprehension, suggesting that higher cognitive flexibility and fluid intelligence were associated with better reading comprehension. Thus, our results point to differential contributions of executive functions to reading comprehension and reading speed.