The publisher regrets that, due to a technical error, the Conflict of Interest declared by the authors was not included in the published paper. We wish to apologise to the authors and to the readers for any inconvenience caused. The Conflict of Interest statement is given below and has been updated in the online version of the paper.

Ashkahn Jahromi owns a float tank facility. His expertise on float tank operation was necessary to appropriately develop the questionnaire on float tank operations.

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