Learning of novel compound nouns - A variant of lexical learning that requires intact verbal short-term memory.

Verbal short-term memory (vSTM) plays a crucial role in word learning, and patients with impaired vSTM have been demonstrated to fail on learning novel word forms. Word learning has exclusively been investigated with previously unknown or pseudowords. Several languages, however, make use of composition, i.e., combining morphemes into compounds. On the one hand, this is comparable to pseudoword learning because known elements are combined into novel representations, on the other hand compounds differ from pseudowords learning because they consist of previously known (lexical) elements. This may help to identify the role of vSTM in word learning. The present paper documents impaired word learning in a participant with impaired vSTM but also assessed, for the first time, the acquisition of novel noun-noun compounds. In two independent experiments, the participant was impaired in learning nonsense compounds ("ball door") and the names of previously unknown tools ("nail puller"; "drill bit"). Control experiments revealed her impairment of word learning and novel compound noun learning to be selective: IS could acquire information about the novel tools' function and purpose and was unimpaired in several experiments on paired associate learning including different stimuli. The results suggest that vSTM is involved in variants of lexical learning such as compound noun acquisition. Implications for the modeling of the relationship between vSTM and word learning are discussed.