The unusual high-pitched cry of the high-risk infant has been shown to be rated as generally more aversive than low-risk infant cries. Because psychophysiological measures may provide sensitive indicators of perceptual differences which occur as a function of the listener's personality, the relation between heat rate (HR) to low-and high-risk infant cries and introversion-extraversion was examined. Introverts were predicted to show a greater amount of HR acceleration to infant cries than extraverts due to the introvert's lower threshold for psychophysiological activity. Extraverts were predicted to show a greater amount of HR deceleration to infant cries due to the extravert's high threshold for psychophysiological activity. A between groups design was used in which 40 introverts and 40 extraverts listened to a series of low-or high-risk infant cries while their HR was monitored. A significant personality by cry type interaction was found for HR acceleration but no significant differences were revealed in the post-hoc tests. Nonparametric analysis, however, revealed that introverts gave reliably more responses of greater HR acceleration to high- than to low-risk infant cries, suggesting that high-risk infant cries are perceived as more aversive. Heightened perceptual awareness by the introvert may be resulting in the greater differentiation of HR responses between cry types. Implications of these findings with child abuse and neglect are discussed. / M.S.