Psychophysics in the field: perception and memory for labor pain.

Separate groups of women estimated the painfulness of labor contractions either immediately (perceptual judgments) or at time intervals varying from 8 to 48 h after their completion (memorial judgments). The pain judgments of individual uterine contractions were related functionally to the biometrically measured magnitude of these contractions. Perceived and remembered painful sensations were related to referent intensities by power functions governed, as a rule, by exponents greater than unity. Exponents for the memory functions were consistently greater than those for the perceptual functions. Psychophysics done in the field can help decide theoretical issues in addition to providing useful practical information.