- Extending Shannon's information theory to human memory constraints (the "magical number")
- Establishing psycholinguistics as a separate and legitimate area of study
- He and J.S. Bruner cofounded the Harvard Center for Cognitive Studies, and later the Princeton Center for Cognitive Studies
- Developer of WordNet, a "a large lexical database of English. Nouns, verbs, adjectives and adverbs are grouped into sets of cognitive synonyms (synsets), each expressing a distinct concept."
I carry WordNet on my netbook and use it several times a week. No doubt I will think of G.A.M. every time the app starts, and his insight so deceptively simple that became as powerful as poetry.