Abstract - Warren

Modeling word learning in adults with memory impairments after brain damage

Abstract: Word learning is critically important across the lifespan whether learning unfamiliar words (e.g., "iPod"), elaborating existing word knowledge (e.g., extending "tablet" to include portable computers) or making new associations between familiar words and novel exemplars (e.g., remembering that the new faculty member is named "Michelle"). All of these rely on coordination between language and memory, and brain injury can impair language, memory, or both simultaneously. Brain-damaged patients offer the unique opportunity to study basic word-learning processes in a new context, with the potential to illuminate the role of specific brain regions in child word learning. The goal of this project is to improve our understanding of how healthy adults learn new words, and to determine how brain injury and memory impairment change the word-learning process. Injuries to certain brain regions, notably the medial temporal lobes and the hippocampus, cause severe memory problems that prevent rapid learning of facts, events, or associations. However, amnesic patients can gradually acquire new memories, including new words, given enough repetition (i.e., slow associative learning). Meanwhile, word learning in childhood is frequently described as a rapid associative process, but recent computational modeling investigations demonstrate that slow associative learning (paired with a rapid decision-making process) is sufficient to support robust word learning. Our project investigates whether similar mechanisms can account for the slow associative learning of memory-impaired adults. In order to test this hypothesis, we will combine neuropsychological testing of healthy and memory-impaired adults with computational modeling of their word-learning. This will improve our understanding of word learning and memory processes more generally, and is potentially relevant to the clinical remediation of disordered memory. (Dave Warren, collaborating with Bob McMurray and Melissa Duff).