Psychonomic Bulletin & Review

, Volume 16, Issue 6, pp 1026–1036 | Cite as

A diffusion model decomposition of the practice effect

  • Gilles Dutilh
  • Joachim Vandekerckhove
  • Francis Tuerlinckx
  • Eric-Jan Wagenmakers
Brief Reports


When people repeatedly perform the same cognitive task, their mean response times (RTs) invariably decrease. The mathematical function that best describes this decrease has been the subject of intense debate. Here, we seek a deeper understanding of the practice effect by simultaneously taking into account the changes in accuracy and in RT distributions with practice, both for correct and error responses. To this end, we used the Ratcliff diffusion model, a successful model of two-choice RTs that decomposes the effect of practice into its constituent psychological processes. Analyses of data from a 10,000-trial lexical decision task demonstrate that practice not only affects the speed of information processing, but also response caution, response bias, and peripheral processing time. We conclude that the practice effect consists of multiple subcomponents, and that it may be hazardous to abstract the interactive combination of these subcomponents in terms of a single output measure such as mean RT for correct responses. Supplemental materials may be downloaded from http://pbr


Posterior Distribution Diffusion Model Lexical Decision Task Drift Rate Practice Effect 
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Copyright information

© Psychonomic Society, Inc. 2009

Authors and Affiliations

  • Gilles Dutilh
    • 1
  • Joachim Vandekerckhove
    • 2
  • Francis Tuerlinckx
    • 2
  • Eric-Jan Wagenmakers
    • 1
  1. 1.Department of PsychologyUniversity of AmsterdamAmsterdamThe Netherlands
  2. 2.Leuven UniversityLeuvenThe Netherlands

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