In clinical practice with young children, gold standard rating scales used to evaluate the pain are VAS (Visual Analogue Scale) and FPS-R (Faces Pain Scale - Revised), which are self-assessment tools. These scales present however certain limitations: the VAS is not applicable if the child does not know how to estimate the distances, as young children, or children with mental retardation. As for FPS-R, it can be frightening for children by the aspect of faces looking like impersonal masks.