nonnutritive sucking
the sucking by infants of objects that do not provide milk (e.g., a thumb, pacifier), in order, for example, to induce calm or aid sleep. The sucking reflex thus plays a part in the development of emotional control and self-regulation. Nonnutritive sucking has been used in research studies as a way of inferring infant preferences, by observing differences in sucking rate as infants are presented with different stimuli.