Judging pain in newborns: facial and cry determinants.

Explored the facial and cry characteristics that adults use when judging an infant's pain. Sixteen women viewed videotaped reactions of 36 newborns subjected to noninvasive thigh rubs and vitamin K injections in the course of routine care and rated discomfort. The group mean interrater reliability was high. Detailed descriptions of the infants' facial reactions and cry sounds permitted specification of the determinants of distress judgments. Several facial variables (a brow bulge, eyes squeezed shut, and deepened nasolabial fold constellation, and taut tongue) accounted for 49% of the variance in ratings of affective discomfort after controlling for ratings of discomfort during a noninvasive event. In a separate analysis not including facial activity, several cry variables (formant frequency, latency to cry) also accounted for variance (38%) in ratings. When the facial and cry variables were considered together, cry variables added little to the prediction of ratings in comparison to facial variables. Cry would seem to command attention, but facial activity, rather than cry, can account for the major variations in adults' judgments of neonatal pain.