TY - JOUR

T1 - Under-resourced or overloaded?

T2 - Rethinking working memory deficits in developmental language disorder

AU - Jones, Samuel

AU - Westermann, Gert

N1 - ©American Psychological Association, 2022. This paper is not the copy of record and may not exactly replicate the authoritative document published in the APA journal. Please do not copy or cite without author's permission. The final article is available, upon publication, at: 10.1037/rev0000338

PY - 2022/11/30

Y1 - 2022/11/30

N2 - Dominant theoretical accounts of developmental language disorder (DLD) commonly invoke workingmemory capacity limitations. In the current report, we present an alternative view: That working memory in DLD is not under-resourced but overloaded due to operating on speech representations with low discriminability. This account is developed through computational simulations involving deep convolutional neural networks trained on spoken word spectrograms in which information is either retained tomimic typical development or degraded to mimic the auditory processing deficits identified among some childrenwith DLD. We assess not only spoken word recognition accuracy and predictive probability and entropy (i.e., predictive distribution spread), but also use mean-field-theory based manifold analysis to assess; (a) internal speech representation dimensionality and (b) classification capacity, a measure of the networks’ ability to isolate any given internal speech representation that is used as a proxy for attentional control.We show that instantiating a low-level auditory processing deficit results in the formation of internal speech representations with atypically high dimensionality, and that classification capacity is exhausted due to low representation separability. These representation and control deficits underpin not only lower performance accuracy but also greater uncertainty even when making accurate predictions in a simulated spoken word recognition task (i.e., predictive distributions with low maximum probability and high entropy), which replicates the response delays and word finding difficulties often seen in DLD. Overall, these simulations demonstrate a theoretical account of speech representation and processing deficits in DLD in which working memory capacity limitations play no causal role.

AB - Dominant theoretical accounts of developmental language disorder (DLD) commonly invoke workingmemory capacity limitations. In the current report, we present an alternative view: That working memory in DLD is not under-resourced but overloaded due to operating on speech representations with low discriminability. This account is developed through computational simulations involving deep convolutional neural networks trained on spoken word spectrograms in which information is either retained tomimic typical development or degraded to mimic the auditory processing deficits identified among some childrenwith DLD. We assess not only spoken word recognition accuracy and predictive probability and entropy (i.e., predictive distribution spread), but also use mean-field-theory based manifold analysis to assess; (a) internal speech representation dimensionality and (b) classification capacity, a measure of the networks’ ability to isolate any given internal speech representation that is used as a proxy for attentional control.We show that instantiating a low-level auditory processing deficit results in the formation of internal speech representations with atypically high dimensionality, and that classification capacity is exhausted due to low representation separability. These representation and control deficits underpin not only lower performance accuracy but also greater uncertainty even when making accurate predictions in a simulated spoken word recognition task (i.e., predictive distributions with low maximum probability and high entropy), which replicates the response delays and word finding difficulties often seen in DLD. Overall, these simulations demonstrate a theoretical account of speech representation and processing deficits in DLD in which working memory capacity limitations play no causal role.

KW - Developmental language disorder (DLD)

KW - Spoken word recognition

KW - Word learning

KW - Convolutional neural network

KW - Manifold geometry

U2 - 10.1037/rev0000338

DO - 10.1037/rev0000338

M3 - Journal article

VL - 129

SP - 1358

EP - 1372

JO - Psychological Review

JF - Psychological Review

SN - 0033-295X

IS - 6

ER -