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Int J Psychophysiol. 2014 Sep;93(3):316-21. doi: 10.1016/j.ijpsycho.2014.06.013. Epub 2014 Jun 27.

Fractal images induce fractal pupil dilations and constrictions.

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  • 1Wake Forest University, United States.
  • 2University of Oregon, United States.


Fractals are self-similar structures or patterns that repeat at increasingly fine magnifications. Research has revealed fractal patterns in many natural and physiological processes. This article investigates pupillary size over time to determine if their oscillations demonstrate a fractal pattern. We predict that pupil size over time will fluctuate in a fractal manner and this may be due to either the fractal neuronal structure or fractal properties of the image viewed. We present evidence that low complexity fractal patterns underlie pupillary oscillations as subjects view spatial fractal patterns. We also present evidence implicating the autonomic nervous system's importance in these patterns. Using the variational method of the box-counting procedure we demonstrate that low complexity fractal patterns are found in changes within pupil size over time in millimeters (mm) and our data suggest that these pupillary oscillation patterns do not depend on the fractal properties of the image viewed.

Copyright © 2014 Elsevier B.V. All rights reserved.


Autonomic nervous system; Fractals; Pupillary oscillations

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