Lexical mediation of phonotactic frequency effects on spoken word recognition: A Granger causality analysis of MRI-constrained MEG/EEG data

Abstract

Phonotactic frequency effects play a crucial role in a number of debates over language processing and representation. It is unclear however, whether these effects reflect prelexical sensitivity to phonotactic frequency, or lexical “gang effects” in speech perception. In this paper, we use Granger causality analysis of MR-constrained MEG/EEG data to understand how phonotactic frequency influences neural processing dynamics during auditory lexical decision. Effective connectivity analysis showed weaker feedforward influence from brain regions involved in acoustic-phonetic processing (superior temporal gyrus) to lexical areas (supramarginal gyrus) for high phonotactic frequency words, but stronger top-down lexical influence for the same items. Low entropy nonwords (nonwords judged to closely resemble real words) showed a similar pattern of interactions between brain regions involved in lexical and acoustic-phonetic processing. These results contradict the predictions of a feedforward model of phonotactic frequency facilitation, but support the predictions of a lexically mediated account.

Using effective connectivity analyses to understand processing architecture: response to commentaries by Samuel, Spivey and McQueen, Eisner and Norris

“…The top-down interpretation is consistent with the predictions of our neurofunctional model of lexically mediated speech perception (Gow, 2012), as well as a series of effective connectivity results we have seen in previous explorations of lexical effects on speech processing (Gow & Nied, 2014; Gow & Olson, 2015a; Gow & Segawa, 2009; Gow et al, 2008). …”

“…The 32 region of interest processing network that our data-driven techniques identify is of typical size compared to networks we have found in analyses of data collected in phoneme identification, picture verification and lexical decision tasks (cf. Gow & Nied, 2014; Gow & Olson, 2015a; Gow & Segawa, 2009; Gow, Segawa, Ahlfors, & Lin, 2008). To our knowledge, no implemented psycholinguistic models of spoken word recognition even approach this level of complexity.…”

Sentential influences on acoustic-phonetic processing: a Granger causality analysis of multimodal imaging data

“…Gow’s dual lexicon model (2012) suggests that the SMG is the home of wordform representations that mediate the mapping between acoustic-phonetic and articulatory representations in speech production and perception. This finding is supported by a series of results that show that SMG influence on pSTG activation accompanies behavioral evidence of lexical influences on speech interpretation (Gow & Nied, 2014; Gow & Olson, under review; Gow et al, 2008). …”

Effective brain network analysis with resting-state EEG data: a comparison between heroin abstinent and non-addicted subjects

“…A number of research groups have applied various kinds of causal measure to estimate the effective brain connectivity on cognitive control, epileptics, lexical mediation studies [25][26][27]. Among the causal measures for estimating effective connectivity, GPDC has good performance in distinguishing between direct and indirect connections.…”