Persistent, paroxysmal crying for more than three hours a day, three or more days a week, is characterised as ‘infant colic,’ which is often attributed to gastrointestinal distress. Longitudinal studies have shown that, as infants get older, their cries become less high-pitched; analysis of home videos suggests that this decline in high-pitched crying is not evident in infants who go on to be diagnosed with autism, whose cries are perceived as more distressing. Infants exposed to alcohol and cocaine in pregnancy may cry less than other infants, that is, are less able to signal their distress to adult caregivers. Parents often report that they can distinguish different types of crying, which help them figure out what exactly their infants need or want, for example, whether the infant is hungry, in pain or needs a nappy change. Infants’ cries can be analysed for features other than pitch, and these other dimensions of crying also influence adults’ perceptions of the cry.