Infants' use of the index finger for social and non-social purposes during the first two years of life: A cross-cultural study.

The emergence of the pointing gesture is a major developmental milestone in human infancy. Pointing fosters preverbal communication and is key for language and theory of mind development. Little is known about its ontogenetic origins and whether its pathway is similar across different cultures. The goal of this study was to examine the theoretical proposal that social pointing is preceded by a non-social use of the index finger and later becomes a social-communicative gesture. Moreover, the study investigated to which extent the emergence of social pointing differs cross-culturally. We assessed non-social index-finger use and social pointing in 647 infants aged 3- to 24 months from 4 different countries (China, Germany, Japan, and Türkiye). Non-social index-finger use and social pointing increased with infants' age, such that social pointing became more dominant than non-social index-finger use with age. Whereas social pointing was reported across countries, its reported frequency differed between cultures with significantly greater social pointing frequency in infants from Türkiye, China, and Germany compared to Japanese infants. Our study supports theoretical proposals of the dominance of non-social index-finger use during early infancy with social pointing becoming more prominent as infants get older. These findings contribute to our understanding of infants' use of their index finger for social and non-social purposes during the first two years of life.