Handedness as a major determinant of functional cradling bias.

Cradling is an interactive activity, involving a manual component that is very often an integral part of cradling. Cradling, while doing something else with the free hand, is referred to here as functional cradling. This study examined the relationship between a person's handedness and what arm he or she prefers to use when functionally cradling a baby doll that resembles a newborn infant. A total of 765 participants took part in the experiment, 403 women and 362 men, between the ages of 4 and 86 years. Left- and mixed-handers were actively recruited. The sample consisted of 64.3% right-handed, 24.7% mixed-handed, and 11.0% left-handed participants. The results showed a clear tendency for participants to cradle in their non-dominant arm (p < .001). Furthermore, this tendency increased with age and it was present in both sexes, although significantly stronger in women than in men. On the other hand, experience with young children through younger siblings and/or being a parent did not increase the likelihood to cradle in the non-dominant arm. It is concluded that humans have a clear functional cradling preference for the non-dominant arm because this enables the dominant arm to engage in other tasks. This might also explain why previous studies have reported a universal left cradling bias because a right-handed majority (intuitively) keeps the dominant hand free when cradling.