Time schedule of the 7-part survey with the scores that were assigned to the photographs of the ferrets.

AU1-5 = action unit 1–5 of the Ferret Grimace Scale (orbital tightening, nose bulging, cheek bulging, ear changes and whisker retraction), presented in random order. Pre-training = intuitive overall pain assessment, post-training = overall pain assessment after being trained on the Ferret Grimace Scale.