Word learning in ASD: the sensorimotor, the perceptual and the symbolic

Abstract

Word learning requires successful pairing of form and meaning. A common hypothesis about the process of word learning is that initially, infants work on identifying the phonological segments corresponding to words (speech analysis), and subsequently map those segments onto meaning. A range of theories have been proposed to account for the underlying mechanisms and factors in this remarkable achievement. While some are mainly concerned with the sensorimotor affordances and perceptual properties of referents out in the world, other theories emphasize the importance of language as a system, and the relations among language units (other words or syntax). Recent approaches inspired by neuro-science suggest that the storage and processing of word meanings is supported by neural systems subserving both the representation of conceptual knowledge and its access and use (Lambon Ralph et al., Nature Reviews Neuroscience 18:42–55, 2017). Developmental disorders have been attested to impact on different aspects of word learning. While impaired word knowledge is not a hallmark of Autism Spectrum Disorder (ASD), and remains largely understudied in this population, there is evidence that there are, sometimes subtle, problems in that domain, reflected in both how such knowledge is acquired and how words are used (Vulchanova et al., Word knowledge and word usage: A cross-disciplinary guide to the mental lexicon, Mouton De Gruyter, 2020). In addition, experimental evidence suggests that children with autism present with specific problems in categorizing the referents of linguistic labels leading to subsequent problems with using those labels (Hartley and Allen, Autism 19:570–579, 2015). Furthermore, deficits have been reported in some of the underlying mechanisms, biases and use of cues in word learning, such as e.g., object shape (Field et al., Journal of Autism and Developmental Disorders 46:1210–1219, 2016; Tek et al., Autism Research 1:208–222, 2008). Finally, it is likely that symbol use might be impaired in ASD, however, the direction of the causal relationship between social and communication impairment in autism and symbolic skills is still an open question (Allen and Lewis, Journal of Autism and Developmental Disorders 45:1–3, 2015; Allen and Butler, British Journal of Developmental Psychology 38:345–362, 2020; Wainwright et al., Journal of Autism and Developmental Disorders 50:2941–2956, 2020). Further support for impaired symbol formation in autism comes from the well-attested problems with figurative, non-literal language use (e.g., metaphors, idioms, hyperbole, irony) (Vulchanova et al., Frontiers in Human Neuroscience 9:24, 2015). Here we propose that embodied theories of cognition which link perceptual experience with conceptual knowledge (see Eigsti, Frontiers in Psychology 4:224, 2013; Klin et al., Philosophical Transactions of the Royal Society of London. Series B: Biological Sciences 358:345–360, 2003) might be useful in explaining the difficulty in symbolic understanding that individuals with autism face during the word learning process.

Mental rotation and language in autism spectrum disorder

“…Furthermore, potential problems at higher levels of abstraction in spatial representation may lead to the observed problems in applying the shape‐bias in word learning in autism. This speculation aligns with the proposal that weakened abstraction and symbolic use may explain the observed semantic problems in word learning in autism (Vulchanova et al, 2023).…”

The association between statistical learning and language development during childhood: A scoping review

“…A promising perspective is to acknowledge the presence of distinct components in the process underlying SL., It has been suggested that statistical learning can be broken down into two dissociable components: (1) perceptual binding of individual stimulus units into integrated composites and (2) storing those integrated representations for later use [ 76 ]. Such a view is consistent with the evidence from word learning in children, whereby the initial stages involve speech segmentation and consolidation of the phonological form, which can subsequently be used for the purposes of mapping onto content [ 20 , 77 , 78 ]. These two respective components of SL can, and should, be studied independently with specifically designed tasks.…”

“…This is not surprising, given the central role of the auditory modality in oral language skills and, specifically, in word segmentation. The role of skills in audio-visual binding is also quite consistent with the process of mapping auditory information (phonological form) to visually available referents corresponding to word meanings, which is an essential step in word learning [ 20 ]. The reviewed studies attest not only concurrent or predictive relationship between SL and vocabulary, but also attest an association in the opposite direction, namely between existing vocabulary knowledge and SL skills.…”

“…SL in the visual domain can be expected to be relevant for language acquisition. This can be easily stipulated on the basis of the relevance of visual input in word learning [ 20 ], but also from the point of view of mechanisms assumed to support the acquisition of grammar (e.g., the lexical bootstrapping hypothesis, [ 21 , 22 ]; and the semantic bootstrapping hypothesis, [ 23 , 24 ]. Yet, only a handful of studies have examined the developmental trajectory of visual SL [ 17 , 18 , 25 ] and the possible association between visual SL and language skills is largely understudied.…”