CONCEPT
Primary Intersubjectivity
Colwyn Trevarthen's term — adopted into the cultural-historical tradition — for the pre-linguistic capacity for mutual engagement between infant and caregiver that grounds all subsequent social development, and the foundation against which AI's simulation of intersubjectivity must be measured.
Primary intersubjectivity names the infant's pre-linguistic capacity for mutual engagement with a caregiver — the turn-taking, the mutual gaze, the contingent responsiveness, the shared emotional attunement — that emerges in the first months of life and predates language. Colwyn Trevarthen introduced the term in the 1970s to describe the specific quality of infant–caregiver interaction that cannot be reduced to stimulus-response but requires the attribution of mutual awareness between participants. The cultural-historical tradition adopted the concept as a foundation for its claim that social interaction is primary in development: the infant is not an isolated cognitive system that later acquires social capacities; she is from the beginning engaged in specifically social forms of exchange.
In The You On AI Field Guide
The concept's AI-era relevance is that it names what contemporary language models can and cannot simulate. AI systems can produce remarkably fluent linguistic interaction — contingent, responsive, seemingly attuned. What they cannot do is participate in