Stroop effects from 3 to 10 years: the critical role of reading acquisition.

We studied 241 nursery and primary school 3- to 10-year old children with a discrete-trial version of the Stroop Test, including both a Color-Naming and (for the 6- to 10-year olds only) a Word-Reading task. The classic Stroop effect was present across all the ages, with an inverted U-shaped pattern: increasing from 3- to 7-year olds, then decreasing. Preschool children who were able to read showed a Stroop effect larger than same-age, unable to read children. The reverse Stroop effect was present across all the studied ages but the 6-year-olds, who instead displayed some facilitation in reading congruent vs. black words. Since the acquisition of reading skills turned out to be crucial for the Stroop effects, the present research may be useful to study developmental reading impairments by providing normative data.