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. 2019 Oct 15;10:2297. doi: 10.3389/fpsyg.2019.02297

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Copyright © 2019 Cross, Gheorma and Pressman.

This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

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The example photograph of a device-free smile that was shown to all participants (written informed consent was obtained from this individual for the publication of this image).