Bridging computational approaches to speech production: The semantic–lexical–auditory–motor model (SLAM)

Abstract

Speech production is studied from both psycholinguistic and motor-control perspectives, with little interaction between the approaches. We assessed the explanatory value of integrating psycholinguistic and motor-control concepts for theories of speech production. By augmenting a popular psycholinguistic model of lexical retrieval with a motor-control-inspired architecture, we created a new computational model to explain speech errors in the context of aphasia. Comparing the model fits to picture-naming data from 255 aphasic patients, we found that our new model improves fits for a theoretically predictable subtype of aphasia: conduction. We discovered that the improved fits for this group were a result of strong auditory-lexical feedback activation, combined with weaker auditory-motor feedforward activation, leading to increased competition from phonologically related neighbors during lexical selection. We discuss the implications of our findings with respect to other extant models of lexical retrieval.

Overcoming duality: the fused bousfieldian function for modeling word production in verbal fluency tasks

“…The particular prolongation in relation to phonemic tasks is in line with the view that phonemic tasks depend more strongly on frontal executive functions (for a review, see J. D. Henry & Crawford, 2004a) in order to restrain inadequate semantic coactivation (Robinson et al, 2012). With respect to the growing body of knowledge regarding process sequencing within the language network (Costa et al, 2009;Dell, 1986;Levelt, 1999;Walker & Hickok, 2015), phonemic VF may be visualized as a partial Binversion^of the usual processing direction.…”

“…Furthermore, since phonological processing is preceded by semantic activation and selection (Costa et al, 2009;Levelt, 1999;Walker & Hickok, 2015), and activation among phonemically related items should trigger their underlying semantic concept (Muller et al, 2010;Vonberg et al, 2014), cross-domain coactivation can be expected by the time a word is articulated. According to our model, Rule II (i.e., prohibition of repetitions) would therefore provoke suppression of the entire conglomerate of associations.…”

“…Indefrey, 2011), the last step of which is likely to interface with the auditory system (Walker & Hickok, 2015). In terms of conceptualization, it has been proposed that different characteristics of a word (such as the item's function, smell, appearance) are represented within anatomically diverse cortical areas (Crosson, 2013;Hart et al, 2013;Pulvermuller, 1999).…”

Evaluating quantitative and conceptual models of speech production: how does SLAM fare?

“…The Semantic-Lexical-Auditory-Motor (SLAM) model of speech production (Walker & Hickok, in press) represents an attempt to evaluate the effects of a theoretically motivated architectural modification of the Semantic-Phonological (SP) model (Foygel & Dell, 2000). The modification involved splitting the phonological layer into two parts: an auditory and a motor component.…”

“… In a previous publication, we presented a new computational model called SLAM (Walker & Hickok, in press), based on the Hierarchical State Feedback Control (HSFC) theory (Hickok, 2012). In his commentary, Goldrick (submitted) claims that SLAM does not represent a theoretical advancement, because it cannot be distinguished from an alternative lexical + post-lexical (LPL) theory proposed by Goldrick and Rapp (2007).…”