The core of his analysis is that human minds are the outcome of a successful series of interactions between infant and caregiver(s). In this Hobson's research has built on foundations established by Colwyn Trevarthen from the mid-1970s onwards. Trevarthen identified distinct steps in pre-lingual infant development, Primary Intersubjectivity and Secondary Intersubjectivity, which endow the infant's developing mind/brain with the architecture necessary for the achievement of symbolic thought.
He is occasionally confused with Associate Professor Peter Hobson (P.R. Hobson) who is a lecturer in the School of Education Studies, University of New England, Australia and specialises in professional ethics and in theory and philosophy of education; or with Professor Peter Hobson (P.R. Hobson) who is a Particle Physicist at Brunel University, UK. They are not related in any way.
Hobson throws further light on this basic claim by examining what occurs in cases where, for genetic or environmental reasons, infants are denied the opportunity to investigate intersubjective relationships. To achieve a rare vantage point on human development without unethical experimentation, Hobson examines cases of autism, Down's syndrome, congenital blindness and extreme social deprivation (for which statistically significant numbers of orphans rescued from Nicolae Ceauşescu's Romanian orphanages were available). The obstacles each of these circumstances placed in the way of normal infant-caregiver interaction are finely examined.
Hobson's argument constitutes a challenge to certain flavors of sociobiology and Evolutionary Psychology, in that it traces the conception of the human mind back to a 'cradle' of social interactions, without which consciousness in the full, human sense is unobtainable. On the other hand, Hobson demonstrates that a hard-wired emotional connection is crucial for an infant to start the process of intersubjective learning. The experience of having an emotion elicited by another human being, and eliciting emotional responses in others, is identified as the material out of which humans fashion their sense of self, other, object and symbol.
Hobson's thesis is of growing interest in Philosophy of Mind and related disciplines. Edward Skidelsky suggests that Hobson fatally overlooks the fact that people with autism learn to speak (see External Links, below). Others have understood Hobson to be blaming parents for autism, a charge explicitly rejected in The Cradle of Thought.