Comparisons of indices of movement discrimination: Psychometric function, information theory, and signal detection analysis

  • Kwee-Yum Lee Australian Catholic University
  • Roger Adams The University of Sydney
  • Hae-Jung Lee Silla University
  • Gordon Waddington


Quantitative assessments of movement discrimination ability are used in sport and rehabilitation to gain insights into the mechanisms of neural function, skill performance under different conditions and recovery after injury. Here, we have for the first time compared three psychophysical measures of discrimination of extent of ankle movements. The movement discrimination sensitivity indices were; the just noticeable difference (JND) derived from the psychometric function, the amount of transmitted information (TI) from information theory, and the area under the ROC curve (AUC) from non-parametric signal detection analysis. Absolute judgements were obtained from 25 participants for the extents of active ankle inversion movements made to physical stops at different depths. Only the AUC showed a significant difference in discrimination scores with depth and a downwards linear trend of lesser scores with greater movement extents. These results are consistent with the previous findings of Cattell and Fullerton (1892) and Magill and Parks (1983).

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