July 17 (UPI) -- A team of international psychologists and neuroscientists have found that humans may be hardwired to lean to the right when kissing their romantic partners.
The study, published July 14 in Scientific Reports, consisted of asking 48 married couples to kiss, at home and in private, and then report about the kiss separately in writing.
Researchers at the University of Dhaka, the University of Bath and The University of Bath Spa all collaborated on the study, which found a preference for turning the head to the right when kissing for both partners.
The study showed men were 15 times more likely than women to initiate kissing and over two-thirds of kiss initiators and recipients turned their heads to the right while kissing.
"Head turning is one of the earliest biases seen in development -- even in the womb a preference for turning the head to the right is observable before that of favoring the right hand or foot," Dr. Rezaul Karim, of the Department of Psychology at the University of Dhaka, said in a press release. "Whether this fundamental bias is innate and extends into adulthood is a lingering question for neuroscience and psychology."
The study suggests handedness may predict head-leaning preference in kiss initiators but not kiss recipients, and that the kiss initiator's head-leaning direction predicted the recipient's head-leaning direction.
"This is the first study to show sex differences in the initiation of kissing, with males more likely being the initiator, and also that the kiss initiators' head-turning direction tends to modulate the head-turning direction in the kiss recipients," Karim said. "Based on our prior theoretical work we are also able to make new hypotheses about the underlying neural basis for these behaviors. "
Researchers suggest that the act of kissing may be determined by the brain splitting up tasks to different hemispheres, particularly the functions of the left cerebral hemisphere located in the emotion and decision-related areas of the brain.