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The power law as behavioral illusion: reappraising the reappraisals

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Abstract

Marken and Shaffer (Exp Brain Res 235:1835–1842, 2017) have argued that the power law of movement, which is generally thought to reflect the mechanisms that produce movement, is actually an example of what Powers (Psychol Rev 85:417–435, 1978) dubbed a behavioral illusion, where an observed relationship between variables is seen as revealing something about the mechanisms that produce a behavior when, in fact, it does not. Zago et al. (Exp Brain Res. https://doi.org/10.1007/s0022-017-5108-z, 2017) and Taylor (Exp Brain Res, https://doi.org/10.1007/s00221-018-5192-8, 2018) have “reappraised” this argument, claiming that it is based on logical, mathematical, statistical and theoretical errors. In the present paper we answer these claims and show that the power law of movement is, indeed, an example of a behavioral illusion. However, we also explain how this apparently negative finding can point the study of movement in a new and more productive direction, with research aimed at understanding movement in terms of its purposes rather than its causes.

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Notes

  1. We now understand D to be a measure of affine velocity (Maoz et al. 2006; Pollick and Sapiro 1997), but we will continue to refer to D as the “cross-product” variable when we are discussing the analysis in Marken and Shaffer (2017).

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Correspondence to Richard S. Marken.

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Marken, R.S., Shaffer, D.M. The power law as behavioral illusion: reappraising the reappraisals. Exp Brain Res 236, 1537–1544 (2018). https://doi.org/10.1007/s00221-018-5208-4

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