Dominant theoretical accounts of developmental language disorder (DLD) commonly invoke working me... more Dominant theoretical accounts of developmental language disorder (DLD) commonly invoke working memory 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 to mimic typical development or degraded to mimic the auditory processing deficits identified among some children with 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; (i) internal speech representation dimensionality, and (ii) classification capacity, a measure of the networks’ ability to isolate any given internal speech representation that is u...
Brain imaging studies of English past tense inflection have found dissociations between regular a... more Brain imaging studies of English past tense inflection have found dissociations between regular and irregular verbs, but no coherent picture has emerged to explain how these dissociations arise. Here we use synthetic brain imaging on a neural network model to provide a mechanistic account of the origins of such dissociations. The model suggests that dissociations between regional activation patterns in verb inflection emerge in an adult processing system that has been shaped through experience-dependent structural brain development. Although these dissociations appear to be between regular and irregular verbs, they arise in the model from a combination of statistical properties including frequency, relationships to other verbs, and phonological complexity, without a causal role for regularity or semantics. These results are consistent with the notion that all inflections are produced in a single associative mechanism. The model generates predictions about the patterning of active br...
Research on lexical development in Down syndrome (DS) has emphasized a dissociation between langu... more Research on lexical development in Down syndrome (DS) has emphasized a dissociation between language comprehension and production abilities, with production of words being relatively more impaired than comprehension. Current theories stress the role of associative learning on lexical development. However, there have been no attempts to explain the atypical lexical development in DS based on atypical associative learning. The long-term potentiation (LTP) and long-term depression (LTD) of synapses, underlying associative learning, are altered in DS. Here we present a neural network model that instantiates notions from neurophysiological studies to account for the disparities between lexical comprehension and production in DS. Our simulations show that an atypical LTP/LTD balance affects comprehension and production differently in an associative model of lexical development.
Variability is important to learning; however, whether it supports or hinders language acquisitio... more Variability is important to learning; however, whether it supports or hinders language acquisition is unclear. 3D object studies suggest that children learn words better when target objects vary, however storybook studies indicate that contextual variability impairs learning. We tested a dynamic systems account in which background variability should boost learning by speeding the emergence of new behaviors. Two groups of two-year-old children saw arrays of one novel and two known objects on a screen, and heard a novel or known label. Stimuli were identical across conditions, with the exception that in the constant condition objects appeared on a white background, and in the variable condition backgrounds were colored. Only children in the variable condition showed evidence of word learning, suggesting that extraneous variability supports learning by decontextualizing representations, and indicating that adding low-level entropy to the developmental system can trigger a change in beh...
Yarkoni’s analysis clearly articulates a number of concerns limiting the generalizability and exp... more Yarkoni’s analysis clearly articulates a number of concerns limiting the generalizability and explanatory power of psychological findings, many of which are compounded in infancy research. ManyBabies addresses these concerns via a radically collaborative, large-scale and open approach to research that is grounded in theory-building, committed to diversification, and focused on understanding sources of variation.
In a seminal study, Yoon, Johnson and Csibra [PNAS, 105, 36 (2008)] showed that nine-month-old in... more In a seminal study, Yoon, Johnson and Csibra [PNAS, 105, 36 (2008)] showed that nine-month-old infants retained qualitatively different information about novel objects in communicative and non-communicative contexts. In a communicative context, the infants encoded the identity of novel objects at the expense of encoding their location, which was preferentially retained in non-communicative contexts. This result has not yet been replicated. Here we attempted two replications, while also including a measure of eye-tracking to obtain more detail of infants’ attention allocation during stimulus presentation. Experiment 1 was designed following the methods described in the original paper. After discussion with one of the original authors, some key changes were made to the methodology in Experiment 2. Neither experiment replicated the results of the original study, with Bayes Factor Analysis suggesting moderate support for the null hypothesis. Both experiments found differential attention...
To account for infants' perceptual and cognitive development, the constructivist model propos... more To account for infants' perceptual and cognitive development, the constructivist model proposes that learning a new object depends on the capability of processing simpler lower-level units, and then integrating these units into more complex higher-level units based on their relationships, such as regular co-occurrence. Here, we demonstrate that the process of associating visual and auditory attributes to build a new multisensory object representation is not only observed in the course of development, but also in the course of infants' in-the-moment information processing. After a brief familiarization session of learning two pairs of novel audiovisual stimuli, 15-month-old infants showed two components in pupil dilations over time: A rapid dilation was observed when processing perceptually novel compared to familiar stimuli, and a slower dilation was observed when processing novel combinations of familiar stimuli. However, in 10-month-old infants, only the effect elicited by...
Journal of experimental child psychology, Nov 9, 2016
The current study uses event-related potential methodologies to investigate how social-cognitive ... more The current study uses event-related potential methodologies to investigate how social-cognitive processes in preverbal infants relate to language performance. We assessed 9-month-olds' understanding of the semantic structure of actions via an N400 event-related potential (ERP) response to action sequences that contained expected and unexpected outcomes. At 9 and 18months of age, infants' language abilities were measured using the Swedish Early Communicative Development Inventory (SECDI). Here we show that 9-month-olds' understanding of the semantic structure of actions, evidenced in an N400 ERP response to action sequences with unexpected outcomes, is related to language comprehension scores at 9months and is related to language production scores at 18months of age. Infants who showed a selective N400 response to unexpected action outcomes are those who are classed as above mean in their language proficiency. The results provide evidence that language performance is rel...
Dominant theoretical accounts of developmental language disorder (DLD) commonly invoke working me... more Dominant theoretical accounts of developmental language disorder (DLD) commonly invoke working memory 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 to mimic typical development or degraded to mimic the auditory processing deficits identified among some children with 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; (i) internal speech representation dimensionality, and (ii) classification capacity, a measure of the networks’ ability to isolate any given internal speech representation that is u...
Brain imaging studies of English past tense inflection have found dissociations between regular a... more Brain imaging studies of English past tense inflection have found dissociations between regular and irregular verbs, but no coherent picture has emerged to explain how these dissociations arise. Here we use synthetic brain imaging on a neural network model to provide a mechanistic account of the origins of such dissociations. The model suggests that dissociations between regional activation patterns in verb inflection emerge in an adult processing system that has been shaped through experience-dependent structural brain development. Although these dissociations appear to be between regular and irregular verbs, they arise in the model from a combination of statistical properties including frequency, relationships to other verbs, and phonological complexity, without a causal role for regularity or semantics. These results are consistent with the notion that all inflections are produced in a single associative mechanism. The model generates predictions about the patterning of active br...
Research on lexical development in Down syndrome (DS) has emphasized a dissociation between langu... more Research on lexical development in Down syndrome (DS) has emphasized a dissociation between language comprehension and production abilities, with production of words being relatively more impaired than comprehension. Current theories stress the role of associative learning on lexical development. However, there have been no attempts to explain the atypical lexical development in DS based on atypical associative learning. The long-term potentiation (LTP) and long-term depression (LTD) of synapses, underlying associative learning, are altered in DS. Here we present a neural network model that instantiates notions from neurophysiological studies to account for the disparities between lexical comprehension and production in DS. Our simulations show that an atypical LTP/LTD balance affects comprehension and production differently in an associative model of lexical development.
Variability is important to learning; however, whether it supports or hinders language acquisitio... more Variability is important to learning; however, whether it supports or hinders language acquisition is unclear. 3D object studies suggest that children learn words better when target objects vary, however storybook studies indicate that contextual variability impairs learning. We tested a dynamic systems account in which background variability should boost learning by speeding the emergence of new behaviors. Two groups of two-year-old children saw arrays of one novel and two known objects on a screen, and heard a novel or known label. Stimuli were identical across conditions, with the exception that in the constant condition objects appeared on a white background, and in the variable condition backgrounds were colored. Only children in the variable condition showed evidence of word learning, suggesting that extraneous variability supports learning by decontextualizing representations, and indicating that adding low-level entropy to the developmental system can trigger a change in beh...
Yarkoni’s analysis clearly articulates a number of concerns limiting the generalizability and exp... more Yarkoni’s analysis clearly articulates a number of concerns limiting the generalizability and explanatory power of psychological findings, many of which are compounded in infancy research. ManyBabies addresses these concerns via a radically collaborative, large-scale and open approach to research that is grounded in theory-building, committed to diversification, and focused on understanding sources of variation.
In a seminal study, Yoon, Johnson and Csibra [PNAS, 105, 36 (2008)] showed that nine-month-old in... more In a seminal study, Yoon, Johnson and Csibra [PNAS, 105, 36 (2008)] showed that nine-month-old infants retained qualitatively different information about novel objects in communicative and non-communicative contexts. In a communicative context, the infants encoded the identity of novel objects at the expense of encoding their location, which was preferentially retained in non-communicative contexts. This result has not yet been replicated. Here we attempted two replications, while also including a measure of eye-tracking to obtain more detail of infants’ attention allocation during stimulus presentation. Experiment 1 was designed following the methods described in the original paper. After discussion with one of the original authors, some key changes were made to the methodology in Experiment 2. Neither experiment replicated the results of the original study, with Bayes Factor Analysis suggesting moderate support for the null hypothesis. Both experiments found differential attention...
To account for infants' perceptual and cognitive development, the constructivist model propos... more To account for infants' perceptual and cognitive development, the constructivist model proposes that learning a new object depends on the capability of processing simpler lower-level units, and then integrating these units into more complex higher-level units based on their relationships, such as regular co-occurrence. Here, we demonstrate that the process of associating visual and auditory attributes to build a new multisensory object representation is not only observed in the course of development, but also in the course of infants' in-the-moment information processing. After a brief familiarization session of learning two pairs of novel audiovisual stimuli, 15-month-old infants showed two components in pupil dilations over time: A rapid dilation was observed when processing perceptually novel compared to familiar stimuli, and a slower dilation was observed when processing novel combinations of familiar stimuli. However, in 10-month-old infants, only the effect elicited by...
Journal of experimental child psychology, Nov 9, 2016
The current study uses event-related potential methodologies to investigate how social-cognitive ... more The current study uses event-related potential methodologies to investigate how social-cognitive processes in preverbal infants relate to language performance. We assessed 9-month-olds' understanding of the semantic structure of actions via an N400 event-related potential (ERP) response to action sequences that contained expected and unexpected outcomes. At 9 and 18months of age, infants' language abilities were measured using the Swedish Early Communicative Development Inventory (SECDI). Here we show that 9-month-olds' understanding of the semantic structure of actions, evidenced in an N400 ERP response to action sequences with unexpected outcomes, is related to language comprehension scores at 9months and is related to language production scores at 18months of age. Infants who showed a selective N400 response to unexpected action outcomes are those who are classed as above mean in their language proficiency. The results provide evidence that language performance is rel...
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Papers by Gert Westermann