When leaning forward to kiss a romantic partner, individuals tend to direct their kiss to the right more often than to the left. The theoretical mechanism guiding this asymmetry is that it originates from a right head-turning preference observed within early stages of human development. By contrast, other lateral turning biases are theorized to stem from differences of hemispheric specialization of emotion rather than from an innate influence, to which the lateral direction of these biases are dependent on their situational context. My first two studies examine if the context for non-romantic conventions of lip-kissing convey a comparable right-turn bias, as the existing literature has focused on romantic-kissing gestures. If kissing laterality is caused from an innately guided right head-turning bias, this directionality should transcend different forms of kissing. Study 1 analysed the turning directions of kisses from videos from the First Kiss social media trend, featuring strangers performing a lip-to-lip kiss. The predominant right-turn bias was not supported; rather, no significant directional bias was observed. To further explore the role of a non-romantic kissing context, study 2 introduced the type of kiss shared between a parent and child. Images of parent-parent kissing (romantic context) and parent-child kissing (parental context) couples were collected for an archival analysis. A right-turn kissing bias was revealed, but only for the romantic kissing couples; for parental kisses, a leftward bias was found. Collectively, the first two studies do not coincide with the congenital account of kissing laterality, as attenuated and reversed turning biases were found.
For study 3, romantic and parental kissing were further investigated while also exploring if perceptual input of kissing biases corresponds to the direction of motor output. Studies 3a and 3b employed a forced-choice task in which image-pairs of romantic and parental kissing couples were presented and asked which image was perceived as more “passionate” and “loving”, respectively. Kisses between romantic couples were perceived to be more passionate when displaying a right turn in comparison to a left turn, whereas images with neither left nor right turns were perceived to be more loving for parent-child kissing couples. The final study examines how cognitive evaluations unrelated to the kiss are influenced in the field of advertising. Original and mirror-reversed versions of advertisements with models kissing were displayed in a forced-choice preference task and consumer-judgement task. Models illustrating a right turn (vs left turn) when kissing were preferred when identical images were presented. When ads were presented individually, right-turn (vs left-turn) kisses resulted in higher consumer attitudes and purchase intention.
This body of research challenges the previous rationale that kissing laterality persists from the right head-turning preference observed in infancy, as contexts with parental and strangers kissing reveal a leftward preference or no directional bias. Our findings also contribute to our understanding of how kissing biases are exhibited within earlier stages of cognitive processing, such that perceptions of passion and consumer preferences for visual stimuli displaying romantic kissing corresponds to the direction of authentic turning behaviour: the right. Further discussion speculates on how cerebral lateralization of emotions may contribute to kissing laterality, to which a variety of future directions are suggested to test these predictions
