Effects of open-set and closed-set task demands on spoken word recognition.

Closed-set tests of spoken word recognition are frequently used in clinical settings to assess the speech discrimination skills of hearing-impaired listeners, particularly children. Speech scientists have reported robust effects of lexical competition and talker variability in open-set tasks but not closed-set tasks, suggesting that closed-set tests of spoken word recognition may not be valid assessments of speech recognition skills. The goal of the current study was to explore some of the task demands that might account for this fundamental difference between open-set and closed-set tasks. In a series of four experiments, we manipulated the number and nature of the response alternatives. Results revealed that as more highly confusable foils were added to the response alternatives, lexical competition and talker variability effects emerged in closed-set tests of spoken word recognition. These results demonstrate a close coupling between task demands and lexical competition effects in lexical access and spoken word recognition processes.