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Psychonomic Bulletin & Review

, Volume 7, Issue 2, pp 185–207 | Cite as

The power law repealed: The case for an exponential law of practice

  • Andrew Heathcote
  • Scott Brown
  • D. J. K. Mewhort
Article

Abstract

The power function is treated as the law relating response time to practice trials. However, the evidence for a power law is flawed, because it is based on averaged data. We report a survey that assessed the form of the practice function for individual learners and learning conditions in paradigms that have shaped theories of skill acquisition. We fit power and exponential functions to 40 sets of data representing 7,910 learning series from 475 subjects in 24 experiments. The exponential function fit better than the power function in all the unaveraged data sets. Averaging produced a bias in favor of the power function. A new practice function based on the exponential, the APEX function, fit better than a power function with an extra, preexperimental practice parameter. Clearly, the best candidate for the law of practice is the exponential or APEX function, not the generally accepted power function. The theoretical implications are discussed.

Keywords

Exponential Function Power Function Learning Rate Journal ofExperimental Psychology Mental Rotation 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Psychonomic Society, Inc. 2000

Authors and Affiliations

  • Andrew Heathcote
    • 1
  • Scott Brown
    • 1
  • D. J. K. Mewhort
    • 2
  1. 1.Department of PsychologyUniversity of NewcastleCallaghanAustralia
  2. 2.Queen’s UniversityKingstonCanada

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