Babies as young as seven months use fake crying to get attention according to new research.
Japanese researchers observed the crying patterns of two girls - aged seven and nine months - over a six month period.
Dr Hiroka Nakayama, from Sacred Heart University in Tokyo, said that the younger child exhibited instances of fake crying that appeared to be to get the mother's attention.
However while most people might take a negative view of fake crying, Dr Nakayama said it can actually have a positive impact on a parent's relationship with their child.
She said fake crying is a useful form of communication that "contributes greatly not only to an infant’s socials envelopment but also to their emotional development."
The children observed for an hour twice a month and recorded with a video camera.
The younger child had 68 crying episodes while the elder child had 34 crying episodes.
The study, which was published in the Infant Behaviour and Development journal, focused on the occurrence of positive and negative emotions in the moments immediately before and after the babies stopped crying.
Negative emotion was defined as when the were infants "were seemingly distressed" while positive emotions were defined as "when infants were seemingly not distressed, or were in a good mood."
While in most cases negative behaviour was observed immediately before and after crying, there were exceptions.
Positive behaviour was observed even just before crying began and also soon after crying stopped. These were crying behaviours that the mother identified as "fake crying" or "emergence of fake crying".
In one instance the younger child was playing with her mother, when the mother moved away (but remained within the infant's sight) from the infant for a short time.
The baby appeared to cry deliberately to get her mother’s attention. When she appeared to be successful and the mother returned, the baby smiled.
Fake crying was more easily spotted, according to the researchers, when the babies tended to smile immediately after crying ceased.
The researchers also noted that the younger baby which exhibited more fake crying behaviour was a sibling whereas the other baby was an only child.
The sibling therefore had to compete for her attention according to the research: "Siblings can enrich social interactions at home and increase their variety. Such environmental factors are known to stimulate the development of communication skills of infants."