I have spent my entire academic career trying to understand human cognition in social, cultural and material context. I was originally trained as a cognitive anthropologist. I believe that cultural practices are a key component of human cognition.

My early work concerned the relationships among language, culture, and thought. In 1975 and 1976, I conducted ethnographic research in the Trobriand Islands of Papua New Guinea. My focus was on reasoning in public litigation. (Culture and Inference, Harvard University Press, 1980).

As a postdoc, I constructed a model of traditional Micronesian navigation based mostly on published accounts of the navigators' practices.

Later, while employed by the US Navy, I used insights derived from first-hand ethnographic studies to build computer-based training systems for steam propulsion systems and for radar navigation. I then moved my observations to the navigation bridge and used that material to write my first attempt at a coherent statement of the principles of distributed cognition. (Cognition in the Wild, MIT Press, 1995).

Since 1989 my primary research sites have been in the world of commercial aviation.