Frequency effects on visual word access in developmental language impairment

Abstract

This paper addresses the issues of frequency and morphological regularity in word recognition and their importance for the organization of the mental lexicon in developmentally language-impaired (DLI) francophones. Two visual lexical decision experiments (one simple, one primed) probe response latencies and response accuracy in DLI participants on frequent and infrequent inflected forms of verbs. DLI participants are mainly sensitive to suffix frequency and show little or no priming effects from primes morphologically related to the target. Results also show that irregularly related primes do not facilitate recognition of the target by participants with DLI. These results are interpreted as indicating that words are not organized according to “morphological families” in the DLI mental lexicon, but rather according to a principle of frequency, and support the hypothesis that words in the DLI mental lexicon lack lexical features and morphological structure. Results indicate that the organization of the mental lexicon of individuals with DLI differs significantly from that of controls.