Development of infant crying behavior: a longitudinal case study.

This study documents the development of infant crying behavior during the second half of the first year (across a key developmental transition). Two female infants were observed twice a month for 6 months when the infants were between 7 and 14 months of age. The infants exhibited crying behavior that seemed to become more sophisticated with increasing age. This marked a proactive stance in communicating with the mother on the part of the infant. Interestingly, at 11-12 months, "fake crying" was observed during a naturalistic interaction with the mother. This implied that deceptive infant behavior could be seen at quite an early stage.