A significant aspect of human social interaction revolves around touching another individual. The most common social touch behaviors are embracing, kissing and the cradling of children, all of which have been demonstrated to be lateralized on the population level in humans. Two major theories have been proposed driving this type of laterality, namely via motor preferences or thorugh an emotional bias. In this study, we systematically tested predictions of both theories as participants had to perform all three social interactions with inanimate objects such as dolls or mannequins in neutral, positive or negative emotional situations. We found that biases in kissing and cradling were unaffected by the handedness of the participants. Only embracing laterality was significantly correlated with handedness. Furthermore, we found that lateralization was reduced in emotional compared to neutral conditions indicating that affective states influence the lateralization of human social touch. Overall, these results thus support the notion that lateral biases in social touch are driven by emotive rather than motor biases.

Packheiser, J., Schmitz, J., Metzen, D., Reinke, P., Radtke, F., Friedrich, P., Güntürkün, O., Peterburs, J. & Ocklenburg , S. (2019): Asymmetries in social touch—motor and emotional biases on lateral preferences in embracing, cradling and kissing, Laterality: Asymmetries of Body, Brain and Cognition.