HMS LANGUAGE PRODUCTION DEFICITS - IMPLICATIONS FOR RELATIONS BETWEENMEMORY, SEMANTIC BINDING, AND THE HIPPOCAMPAL SYSTEM

To test the claim that H.M. exhibits a ''pure memory deficit'' that ha s left his language production intact, we compared the language produc tion of H.M. and controls in three studies. In Study 1. participants d escribed the two meanings of visually presented sentences that they kn ew were ambiguous, and H.M.'s descriptions suggested a semantic-level production deficit: Relative to controls of comparable age, intelligen ce, and education, H.M.'s descriptions were significantly less effecti ve, less clear, less concise. and more repetitious at lexical, phrase. and sentence levels of language production. In Study 2, naive judges rated H.M.'s descriptions as less grammatical, less comprehensible, an d less coherent than descriptions of controls. Study 3 replicated thes e results for conversational speech about childhood events that occurr ed ion before H.M.'s operation. his epilepsy, and his epilepsy treatme nts. Present results contradict stages of processing theories that loc alize H.M.'s deficit to a storage stage that is independent of process es for retrieving and producing verbal materials, and instead support a distributed-memory theory in which memory storage and retrieval invo lving verbal materials are inherent aspects of normal language product ion. (C) 1998 Academic Press.