Poster #: 102
Topic: Speech and language (incl. deficits)
Friday, Sep 11, 2015
Temporo-spatial decomposition of MMN reveals underspecified phoneme representations
1Linguistics and Cognitive Science, Universit of Delaware, Newark, DE, United States
2Linguistics, Michigan State University, Germany
The theory of phonological underspecification (Halle, 1959; Hall, 2007) states that the phonemes that make up words in long-term memory are only coded for a subset of the articulatory features needed for pronounciation. Recent psychological support for underspecification comes from acquisition studies (Fikkert and Levelt, 2008) and ERP studies (Eulitz and Lahiri, 2004; Lahiri and Reetz, 2010). Our study tested a theoretical proposal by (Iverson and Salmons, 1995) that English voiceless stops are coded for a voicelessness feature in lexical representations, but that voiced stops are not coded (i.e. underspecified) for voicing specification. We tested this by utilizing the multi-standard MMN paradigm (Phillips et al., 2000), which causes a phonetic representation to be compared to a phonological representation, allowing us to test a fully specified feature matrix against a partially specified feature matrix. We present here both new data and a reanalysis of results presented at the previous MMN conference, by using difference waveforms as input to temporo-spatial PCA (Dien and Frishkoff, 2005; Dien, 2012); which captures spatial differences in topography of MMN for /d/ vs. /t/. As predicted by underspecification theory, we found a greater MMN to a phonetic oddball [d] in two multiple-standard MMN experiments (with and without attention to the stimuli). Furthermore, we predicted, and observed significant MMNs for both /d/ and /t/ in a single-standard MMN paradigm (but /d/ and /t/ MMNs were observed via ICA to have different spatial distributions). The results support a theory with underspecification at the phonological, but not phonetic level.