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Children Are Not Like Older Adults: A Diffusion Model Analysis of Developmental Changes in Speeded Responses


  • Preparation of this article was supported by NIA Grant R01-AG17083 and NIMH Grant R37-MH44640 to the first author. We would like to thank Russ Childers for his programming assistance, as well as the parents, teachers, administrators, and students from St. Agatha Catholic School, Columbus Academy, Upper Arlington School District, Worthington School District (all from Ohio), and Bentworth School District (Pennsylvania).

concerning this article should be addressed to Roger Ratcliff, The Ohio State University, Department of Psychology, 291 Psychology Building, 1835 Neil Avenue, Columbus, OH 43210. Electronic mail may be sent to


Children (= 130; Mage = 8.51–15.68 years) and college-aged adults (= 72; Mage = 20.50 years) completed numerosity discrimination and lexical decision tasks. Children produced longer response times (RTs) than adults. R. Ratcliff’s (1978) diffusion model, which divides processing into components (e.g., quality of evidence, decision criteria settings, nondecision time), was fit to the accuracy and RT distribution data. Differences in all components were responsible for slowing in children in these tasks. Children extract lower quality evidence than college-aged adults, unlike older adults who extract a similar quality of evidence as college-aged adults. Thus, processing components responsible for changes in RTs at the beginning of the life span are somewhat different from those responsible for changes occurring with healthy aging.