Intraoral sucrose (and other sweet carbohydrates) induce rapid and sustained calming in crying newborns and transiently increase mouthing and hand-mouth contact ("sucrose effects"). To investigate whether these effects are due to the sweetness of sucrose, 60 crying newborns were randomized to receive 250 microL of 24% sucrose solution, 0.12% of aspartame solution of equivalent sweetness (to adults), or 24% polycose, a soluble carbohydrate that is only very slightly sweet (to adults), as well as water in a mixed parallel crossover design. Relative to water, sucrose persistently reduced crying, and transiently increased mouthing and hand-mouth contact, as previously demonstrated. Aspartame also reduced crying, and transiently increased mouthing and hand-mouth contact, virtually mimicking the time course and the magnitude of the effects obtained in response to sucrose. By contrast, polycose solution had no specific effects on crying, mouthing, or hand-mouth contact. The results imply that the responses of crying newborns to intraoral sucrose are neither specific to sucrose nor to the general class of carbohydrates, and that these effects are more appropriately understood as "sweetness" effects.