Fig 3. Reporting Quality and Risk of Bias.

Reporting Quality was assessed by answered the question if any sort of randomization was reported in the methods section. Risk of Bias was assessed using a modified version of SYRCLE Risk of Bias Tool in 55 experiments that used rat tickling. Unclear risk indicates that studies did not report whether bias was mitigated or not. Low risk indicates there was proper bias mitigation. Medium risk indicates that only part of the randomization was reported or outcome assessment was blinded. High risk of bias indicates there was a clear indication of potential bias. Not applicable bias indicates that the source of bias was not relevant. For example, random allocation of animals when all animals received the same treatment at the same time.