A functional measurement approach to the Children’s Anxiety and Pain Scale-CAPS: contributions to its construct validity

The Children's Anxiety and Pain Scales - CAPS (Kuttner & LePage, 1989) is the only faces measure to date aimed at separately assessing anxiety and pain intensity through self-report. Despite early indications that the two sets of schematic faces included in the CAPS possess face validity regarding the constructs of anxiety/fear and pain, the extent to which they allow differentiating between them has remained controversial, especially in younger children. In this study, the inner features of CAPS's faces were taken as factors in integration tasks performed by children differing in age (6-8 and 9-11 years old) and pain experience (pain-free and acute postoperative pain). Different integration patterns were found for the CAPS-pain and the CAPS-anxiety subscales, along with distinct profiles of relative importance among upper-and lower-face features. These differences did not depend on the assigned judgment dimension (conveyed pain or conveyed fear), and partly concurred with collateral evidence on the relative importance of facial features in prototypical pain and fear expressions. Overall, outcomes were supportive of several facets of the construct validity of the CAPS.