addendum: Adult persistence of head-turning asymmetry

Abstract

A preference to turn the head to the right during the final wks of gestation and during the neonatal period are examples of behavioral asymmetry and is thought to influence perceptual and motor development. The author shows that twice as many adults turn their heads to the right as to the left when kissing, indicating that this head-motor bias persist into adulthood. The findings may be linked to other forms of sidedness that do not become established until long after the newborn head-turning preference has disappeared. Kissing couples were observed in public places (aged 13-70 yrs). The head turning behavior of each couple was recorded for a single kiss, with only the first being counted in instances of multiple kissing. Of 124 Kissing pairs 80 turned their head to the right and 44 turned to the left. As couples come from a biologically adult age range, this result indicates that adults have a head turning bias towards the right side, just like embryos and newborns. The incidence of right-handedness is about 8:1 so this particular asymmetry cannot be the result of a simple bias attributable to a right-sided head turning tendency, the genetic origins of this trait may be different, or cultural factors may have modified an original pattern.