Cascaded processing develops by five years of age: evidence from adult and child picture naming

Although there is compelling evidence for cascading activation in adult lexical planning, there is little research on how and when cascaded processing develops. We use a picture naming task to compare word planning in adults and five-year-old children. We manipulated image codability (name agreement) and name frequency, factors that affect lexical selection and phonological encoding, respectively. These factors had qualitatively similar influences on naming response time in both populations, suggesting similar underlying planning processes. Critically, we found an under-additive interaction between codability and frequency such that the frequency effect was attenuated when name agreement was low. This interaction generalises across experiments and languages and can be simulated in a planning architecture in which phonological forms become activated before lexical selection is complete. These results provide evidence for cascaded processing at an earlier age than previous studies, suggesting that informational cascades are a fundamental property of the production architecture.