‘Left cradling bias’ linked to better social cognitive abilities in children

A study of 98 typically developing children showed that those who cradle dolls on the left side show higher social cognitive abilities than those who do not, indicating the importance of the left cradling bias in children’s social development.

The existence of a ‘left cradling bias’ - the phenomenon that humans will typically cradle a baby on their left side, and so both parent and child keep the other in their left visual field– has long been known, and is already present in even very young children. Scientists at Birkbeck and City, University London have built on this knowledge with new research showing that children who demonstrate this bias by cradling dolls on the left show higher social cognitive abilities than those who do not, indicating the importance of the bias in children’s social development.

The study was conducted with 98 typically developing children (54 girls and 44 boys) in reception or year 1 at a mainstream reception school in South London, who were given a human infant doll to cradle.

Children held the infant human doll significantly more often in a left cradling position and the children who did show this bias had a significantly higher social ability score compared with those who held the doll on the right.

The social ability traits tested including likeliness to follow rules, willingness to share with others and an expressed wish to please their teachers.

The children were also given a pillow to cradle, with three dots marked on to suggest a face. They were also significantly more likely to cradle this object on the left, which the researchers say indicates the depth of the evolutionary bias, as even a hint of a face will trigger the response.

By contrast, when given a plain pillow, without a suggestion of a face, the children demonstrated neither a left nor right cradling bias.

Birkbeck’s Dr Gillian Forrester, who led the study, said: “Faces are so special to humans that just three dots arranged as a face can change behaviour - an effect already present in childhood. Children held a plain pillow randomly in either arm, but adding a ‘three-dot-face’ resulted in a preference to hold in the left arm, mirroring the left-cradling bias shown by mothers holding babies.

“Left-cradling places the baby’s face in the mother’s left visual field. The left visual field is directly connected to the brain’s right hemisphere, which is specialised for processing social-emotional information. Studies show this effect is not related to handedness. A left bias was also seen when children held a human ‘baby’ doll.  Children who held the ‘baby’ doll in their left arm scored higher on social ability tests, compared with right holders, indicating that the left-cradling bias is an evolutionarily old trait supporting infant well-being and social development.”

Approximately 70% of mothers cradle their infants on the left side of their own bodies across activities – such as calming or feeding – the mother’s dominant hand, or culture. This enhances social-emotional stimuli and communication between parent and child since information from the left visual field is processed by the right hemisphere of the brain.

The peer-reviewed study is published in Cortex

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