The signed mental lexicon: Effects of phonological neighborhood density, iconicity, and childhood language experience

Abstract

Most of what is known about the mental lexicon comes from studies of spoken language and their written forms. Signs differ from spoken/written words in two important ways that may affect lexical recognition: their phonological composition is unique (e.g., more simultaneous than serial structure; few minimal pairs) and many signs are iconic. Using an unprimed lexical decision task in American Sign Language (ASL) and the first available estimates of phonological neighborhood density for any sign language, we found that phonological neighborhood density had an inhibitory effect on latency among low frequency signs. This is the first clear evidence that phonological neighbors spontaneously compete during sign recognition. Iconicity negatively affected accuracy but not reaction times, suggesting that iconicity plays a role in task-related decision processes but not lexical retrieval. Many deaf signers have delayed first language acquisition, and we found that language deprivation had lasting, negative effects on phonological processing and sign recognition speed and accuracy. This work indicates that the lexicons of both spoken and signed languages are organized by form, that lexical recognition occurs through form-based competition (most evident for low frequency items), and that form-meaning mappings do not drive lexical access even when iconicity is pervasive in the lexicon.