Abstract
The process by which two people share attention towards the same object or event is called joint attention. Joint attention and the underlying triadic representations between self, other person and object are thought to be unique to humans, supporting teaching, cooperation and language learning. Despite the progress that has been made in understanding the behavioural importance of joint attention during early social development, almost nothing is known about the brain substrate that supports joint attention in the developing infant. We examined responses in five-month-old infants' prefrontal cortex during triadic social interactions using near-infrared spectroscopy. The results demonstrate that, even by the age of five months, infants are sensitive to triadic interactions and, like adults, they recruit a specific brain region localized in left dorsal prefrontal cortex when engaged in joint attention with another person. This suggests that the human infant is neurobiologically prepared for sharing attention with other humans, which may provide the basis for a wide variety of uniquely human social and cultural learning processes.