The Relative Contribution of Root and Word Lexical Properties on Post-Lexical Processing
Our research looks at the role morpheme and word-based lexical representations play in post-lexical processing. Specifically, we are interested in whether in inflected words post-lexical phonological processes inherit the lexical properties of their parent morpheme and/or the whole word.
Given that frequency and phonological neighborhood density are correlated with vowel space (e.g., Munson & Solomon, 2004; Wright, 2004; Yao, 2011), is the vowel space of inflected words influenced by the frequency of roots or whole words? In this study, participants read words from three lists: target inflected words (figs), monomorphemic root controls that matched the root of the target words in frequency and neighborhood density, and monomorphemic word controls that matched the surface form of the target words in frequency and neighborhood density. The vowel space of inflected words was similar to the root controls, but different from the word controls. This suggests that root rather than whole-word lexical representations dominate post-lexical processing.
Frequency is negatively correlated with word duration in monomorphemic words (e.g., Gahl, 2008; Kilanski, 2009). This study looked at whether the duration of inflected words was better predicted by the frequency of roots or whole words. Using the Buckeye corpus, a series of mixed effects linear regressions were performed controlling for speakers’ age and gender, number of phonemes, part of speech, predictability, predicted duration, and phonological neighborhood density. While root frequency predicted duration of corresponding segments (initial phoneme and rhyme duration), there was no independent contribution of word frequency above and beyond root frequency. Again this suggests that root rather than word lexical properties influence post-lexical processing of inflected words. In addition, neither frequency measure predicted the final phoneme of the inflected words, though frequency did predict the final phoneme duration in monomorphemic words. This indicates that post-lexical processes inherit the lexical properties directly from their parent morpheme.
Though there is substantial evidence that the age a person acquires language is related to their development of theory of mind, the exact nature of this relationship is still unclear. Deaf people who use ASL represent a special population because their exposure to language and age of acquisition varies depending on whether their parents are Deaf (and use ASL with them from birth) or are hearing (and are delayed in using ASL). Using neuroimaging, we interested in how these unique language backgrounds influence the developmental trajectory of theory of mind as well as theory of mind processing in general. Keep an eye out for the results of this study!