Investigating the relationship between fast mapping, retention, and generalisation of words in children with autism spectrum disorder and typical development

How do Autistic and Neurotypical Children's Interests Influence their Accuracy During Novel Word Learning?

Word learning depends on attention - children must focus on the right things at the right times. However, autistic children often display restricted interests, limiting their intake of stimuli during word learning. This study investigates how category interests influence word learning in autism and neurotypical development. Autistic and neurotypical children matched on receptive vocabulary used a touch-screen computer to learn novel words associated with animals (high-interest stimuli) and objects (neutral-interest stimuli) via fast mapping. Response accuracy and speed were examined at referent selection, 5-minute retention, and 24-hour retention. Both groups identified meanings of novel words associated with unfamiliar animals and objects via mutual exclusivity with comparable accuracy. After 5 minutes, autistic children retained animal names with greater accuracy than neurotypical children. Autistic children showed a greater increase in their accuracy between 5-minute and 24-hour retention and outperformed neurotypical children across conditions after a night's sleep. Across groups, 24-hour retention was predicted by number of target word repetitions heard at referent selection, indicating a relationship between fast mapping input and retention. However, autistic children were slower to respond correctly, particularly in the animal condition. For autistic children, superior word learning associated with high-interest stimuli was relatively short-term, as sleep appeared to consolidate their memory representations for neutral-interest stimuli. Although these results demonstrate that fundamental word learning mechanisms are not atypical in autism, slower response times may signal a speed-accuracy trade-off that could have implications for naturalistic language acquisition. Our findings also indicate favourable environmental conditions to scaffold word learning.

Predictive Processing During Cue-Outcome Associative Learning in Autistic Children

PURPOSE

Predictive coding theories posit that autism is characterized by an over-adjustment to prediction errors, resulting in frequent updates of prior beliefs. Atypical weighting of prediction errors is generally considered to negatively impact the construction of stable models of the world, but may also yield beneficial effects. In a novel associative learning paradigm, we investigated whether unexpected events trigger faster learning updates in favour of subtle but fully predictive cues in autistic children compared to their non-autistic counterparts. We also explored the relationship between children's language proficiency and their predictive performances.

METHODS

Anticipatory fixations and explicit predictions were recorded during three associative learning tasks with deterministic or probabilistic contingencies. One of the probabilistic tasks was designed so that a fully predictive but subtle cue was overshadowed by a less predictive salient one.

RESULTS

Both autistic and non-autistic children based their learning on the salient cue, and, contrary to our predictions, showed no signs of updating in favour of the subtle cue. While both groups demonstrated associative learning, autistic children made less accurate explicit predictions than their non-autistic peers in all tasks. Explicit prediction performances were positively correlated with language proficiency in non-autistic children, but no such correlation was observed in autistic children.

CONCLUSION

These results suggest no over-adjustment to prediction errors in autistic children and highlight the need to control for general performance in cue-outcome associative learning in predictive processing studies. Further research is needed to explore the nature of the relationship between predictive processing and language development in autism.

Do focused interests support word learning? A study with autistic and nonautistic children

Although focused interests are often associated with a diagnosis of autism, they are common in nonautistic individuals as well. Previous studies have explored how these interests impact cognitive, social, and language development. While some research has suggested that strong interests can detract from learning (particularly for autistic children), newer research has indicated that they can be advantageous. In this pre-registered study, we asked whether focused interests support word learning in 44 autistic children and a vocabulary-matched sample of 44 nonautistic children (mean ages 58 and 34 months respectively). In a word-learning task administered over Zoom, children were exposed to an action labeled by a novel word. The action was either depicted by their focused interest or by a neutral image; stimuli were personalized for each child. At test, they were asked to identify the referent of the novel word, and their eye gaze was evaluated as a measure of learning. The preregistered analyses revealed an effect of focused interests, and post-hoc analyses clarified that autistic children learned the novel word in both the focused interest and neutral conditions, while nonautistic children only showed evidence of learning in the neutral condition. These results suggest that focused interests are not disruptive for vocabulary learning in autism, and thus they could be utilized in programming that supports early language learning in this population.

Understanding speech and language in tuberous sclerosis complex

Tuberous Sclerosis Complex (TSC), is a neurocutaneous disorder, associated with a high prevalence of autism spectrum disorder (ASD; ∼50% of individuals). As TSC is a leading cause of syndromic ASD, understanding language development in this population would not only be important for individuals with TSC but may also have implications for those with other causes of syndromic and idiopathic ASD. In this mini review, we consider what is known about language development in this population and how speech and language in TSC are related to ASD. Although up to 70% of individuals with TSC report language difficulties, much of the limited research to date on language in TSC has been based on summary scores from standardized assessments. Missing is a detailed understanding of the mechanisms driving speech and language in TSC and how they relate to ASD. Here, we review recent work suggesting that canonical babbling and volubility-two precursors of language development that predict the emergence of speech and are delayed in infants with idiopathic ASD-are also delayed in infants with TSC. We then look to the broader literature on language development to identify other early precursors of language development that tend to be delayed in children with autism as a guide for future research on speech and language in TSC. We argue that vocal turn-taking, shared attention, and fast mapping are three such skills that can provide important information about how speech and language develop in TSC and where potential delays come from. The overall goal of this line of research is to not only illuminate the trajectory of language in TSC with and without ASD, but to ultimately find strategies for earlier recognition and treatment of the pervasive language difficulties in this population.

The timescales of word learning in children with language delays: In-the-moment mapping, retention, and generalization

Learning new words and, subsequently, a lexicon, is a time-extended process requiring encoding of word-referent pairs, retention of that information, and generalization to other exemplars of the category. Some children, however, fail in one or more of these processes resulting in language delays. The present study examines the abilities of children who vary in vocabulary size (including both children with normal language (NL) and late talking (LT) children) across multiple timescales/processes - known and novel word mapping, novel word retention, and novel noun generalization. Results indicate that children with lower language skills suffer from deficits in quick in-the-moment mapping of known words compared to their NL peers, but age and vocabulary size rather than normative vocabulary ranking or NL/LT status better predicts performance on retention and generalization processes. Implications for understanding language development as a holistic process with multiple interacting variables are discussed.

Atypical vocabulary acquisition in autism: where is it coming from?

Word-learning development is extremely varied among children with autism, with some showing a peak of abilities in vocabulary and others little or no comprehension or expression of isolated words. Typical word learning mechanisms, such as the application of mutual exclusivity, cross-situational mapping, the whole-object principle, and the noun-naming bias also share this heterogeneity: some mechanisms appear to develop in a typical fashion and others depend on the individuals’ language level. The reason for which word-learning processes could be atypical in autism is still the object of debate. Atypical attentional biases or early social interaction could both play a role in early word acquisition. But it is also unclear whether differences in vocabulary acquisition simply reflect the impact of co-morbid language impairment or there is a degree of specificity in autism. Finally, I propose that a more dimensional view in the study of word learning could be useful to move the field forward.

Motivation from Agency and Reward in Typical Development and Autism: Narrative Review of Behavioral and Neural Evidence

Our ability to perform voluntary actions and make choices is shaped by the motivation from having control over the resulting effects (agency) and positive outcomes (reward). We offer an overview of distinct and common behavioral and neural signatures of agency and reward. We discuss their typical and atypical developmental trajectories, focusing on autism spectrum disorder (ASD), which is characterized by neurodiverse processes underlying action selection. We propose that reduced sensitivity to agency and reward in ASD may be related to atypical multisensory processes and motor planning, with potential for understanding restricted and repetitive behaviors. We emphasize the limitations of the existing literature, and prospects for future research. Understanding the neurocognitive processes that shape the way people with ASD select actions and perceive outcomes is essential to support not only learning, but also volition and self-determination.

Use of Mutual Exclusivity and its Relationship to Language Ability in Toddlers with Autism Spectrum Disorder

To efficiently learn new words, children use constraints such as mutual exclusivity (ME) to narrow the search for potential referents. The current study investigated the use of ME in toddlers with autism spectrum disorder (ASD) and neurotypical (NT) peers matched on nonverbal cognition. Thirty-two toddlers with ASD and 26 NT toddlers participated in a looking-while-listening task. Images of novel and familiar objects were presented along with a novel or familiar label. Overall, toddlers with ASD showed less efficient looking toward a novel referent when a novel label was presented compared to NT toddlers, controlling for age and familiar word knowledge. However, toddlers with ASD and higher language ability demonstrated more robust use of ME than those with lower language ability.

Investigating the Mechanisms Driving Referent Selection and Retention in Toddlers at Typical and Elevated Likelihood for Autism Spectrum Disorder

It was suggested that children's referent selection may not lay memory traces sufficiently strong to lead to retention of new word-object mappings. If this was the case we expect incorrect selections to be easily rectified through feedback. Previous work suggested this to be the case in toddlers at typical likelihood (TL) but not in those at elevated likelihood (EL) for autism spectrum disorder (ASD) (Bedford et al., ). Yet group differences in lexical knowledge may have confounded these findings. Here, TL (N = 29) and EL toddlers (N = 75) chose one of two unfamiliar objects as a referent for a new word. Both groups retained the word-referent mapping above chance when their choices were immediately reinforced but were at chance after corrective feedback. The same pattern of results was obtained when children observed another experimenter make the initial referent choice. Thus, children's referent choices lay memory traces that compete with subsequent correction; these strong word-object associations are not a result of children actively choosing potential referents for new words.

Multiple Mechanisms of Word Learning in Late-Talking Children: A Longitudinal Study

PURPOSE

The aim of this study was to identify variability in word-learning mechanisms used by late-talking children using a longitudinal study design, which may explain variability in late-talking children's outcomes.

METHOD

A cohort of typically developing children (n = 40) and children who were classified as late-talking children at age 2;0 (years;months; ≤ 10th percentile on expressive vocabulary, n = 21) were followed up at ages 3;0 and 3;6. We tested the cohort across tasks designed to isolate different mechanisms involved in word learning: encoding and producing spoken forms of words (using a nonword repetition task), identifying referents for words (using a fast mapping task), and learning associations between words and referents (using a cross-situational word-learning task).

RESULTS

Late-talking children had lower accuracy on nonword repetition than typically developing children, despite most of the sample reaching typical ranges for expressive vocabulary at age 3;6. There were no between-groups differences in fast mapping and retention accuracy; however, both were predicted by concurrent expressive vocabulary. Late-talking children performed less accurately than typically developing children on cross-situational word-learning retention trials, despite showing no between-groups differences during training trials. Combining performance across all three tasks predicted approximately 45% of the variance in vocabulary outcomes at the last time point.

CONCLUSIONS

Late-talking children continue to have deficits in phonological representation that impact their word-learning ability and expressive language abilities but do not show difficulties in fast mapping novel words. Late-talking children may also struggle to retain associative information about word-referent mappings. Late-talking children thus use some, but not all, word-learning mechanisms differently than typically developing children.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.20405856.

Visual perceptual salience and novel referent selection in children with and without autism spectrum disorder

Background & Aims

Many young children with autism spectrum disorder (ASD) demonstrate striking delays in early vocabulary development. Experimental studies that teach the meanings of novel nonwords can determine the effects of linguistic and attentional factors. One factor that may affect novel referent selection in children with ASD is visual perceptual salience-how interesting (i.e., striking) stimuli are on the basis of their visual properties. The goal of the current study was to determine how the perceptual salience of objects affected novel referent selection in children with ASD and children who are typically developing (TD) of similar ages (mean age 3-4 years).

Methods

Using a screen-based experimental paradigm, children were taught the names of four unfamiliar objects: two high-salience objects and two low-salience objects. Their comprehension of the novel words was assessed in low-difficulty and high-difficulty trials. Gaze location was determined from video by trained research assistants.

Results

Contrary to initial predictions, findings indicated that high perceptual salience disrupted novel referent selection in the children with ASD but facilitated attention to the target object in age-matched TD peers. The children with ASD showed no significant evidence of successful novel referent selection in the high-difficulty trials. Exploratory reaction time analyses suggested that the children with autism showed "stickier" attention-had more difficulty disengaging (i.e., looking away)-from high-salience distracter images than low-salience distracter images, even though the two images were balanced in salience for any given test trial.

Conclusions and Clinical Implications

These findings add to growing evidence that high perceptual salience has the potential to disrupt novel referent selection in children with ASD. These results underscore the complexity of novel referent selection and highlight the importance of taking the immediate testing context into account. In particular, it is important to acknowledge that screen-based assessments and screen-based learning activities used with children with ASD are not immune to the effects of lower level visual features, such as perceptual salience.

Caregivers use gesture contingently to support word learning

Children learn words in environments where there is considerable variability, both in terms of the number of possible referents for novel words, and the availability of cues to support word-referent mappings. How caregivers adapt their gestural cues to referential uncertainty has not yet been explored. We tested a computational model of cross-situational word learning that examined the value of a variable gesture cue during training across conditions of varying referential uncertainty. We found that gesture had a greater benefit for referential uncertainty, but unexpectedly also found that learning was best when there was variability in both the environment (number of referents) and gestural cue use. We demonstrated that these results are reflected behaviourally in an experimental word-learning study involving children aged 18-24-month-olds and their caregivers. Under similar conditions to the computational model, caregivers not only used gesture more when there were more potential referents for novel words, but children also learned best when there was some referential ambiguity for words. Thus, caregivers are sensitive to referential uncertainty in the environment and adapt their gestures accordingly, and children are able to respond to environmental variability to learn more robustly. These results imply that training under variable circumstances may actually benefit learning, rather than hinder it.

Morpholexical Processes in Children with Autism Spectrum Disorder: Evidence from Artificial Word Learning

OBJECTIVES

This study aims to investigate the ability of high-functioning children with autism spectrum disorder and normal language (ALN) to learn artificial words, and to investigate their ability to use their knowledge of morphophonological patterns for this learning.

METHODS

Children with ALN and typically developing (TD) children, matched for cognitive and language measures, learned 8 artificial Hebrew words during two daily practice sessions by means of identification and naming tasks. Half the words were constructed from existing morphophonological patterns, and the other half were constructed from pseudo-morphophonological patterns. The two types of words allowed the investigation of the participants' ability to use their knowledge of morphophonological patterns (morpholexical processes) for word learning. Both accuracy and speed were measured.

RESULTS

The ALN group improved incrementally at a rate (slope) similar to that of the TD group in identifying and naming the artificial words, in both accuracy and speed. However, the ALN group were slower than their TD peers in learning to identify the artificial words. Both groups demonstrated higher accuracy and faster speed in both tasks in learning the artificial words with existing morphophonological patterns than those with pseudo-patterns. However, this gap was smaller in the ALN group in the accuracy of naming and marginal in speed of identification.

CONCLUSIONS

Children with ALN possess a lexical learning mechanism that is qualitatively not atypical but may be less efficient than that of their TD peers, including exploiting knowledge of morphophonological patterns - where such patterns exist - for word learning.

Are Children With Autism More Likely to Retain Object Names When Learning From Colour Photographs or Black-and-White Cartoons?

For the first time, this study investigated whether children with autism spectrum disorder (ASD) and typically developing (TD) children matched on language comprehension (M age equivalent =  ~ 44 months) are more likely to retain words when learning from colour photographs than black-and-white cartoons. Participants used mutual exclusivity to fast map novel word-picture relationships and retention was assessed following a 5-min delay. Children with ASD achieved significantly greater retention accuracy when learning from photographs rather than cartoons and, surprisingly, responded more accurately than TD children when learning from photographs. Our results demonstrate that children with ASD benefit from greater iconicity when learning words from pictures, providing a data-grounded rationale for using colour photographs when administering picture-based interventions.

Comparing cross-situational word learning, retention, and generalisation in children with autism and typical development

Word learning is complicated by referential ambiguity - there are often multiple potential targets for a newly-heard word. While typically developing (TD) children can accurately infer word meanings from cross-situational statistics, specific difficulties tracking word-object co-occurrences may contribute to language impairments in autism spectrum disorder (ASD). Here, we investigate cross-situational word learning as an integrated system including mapping, retention, and generalisation in both typical development and autism. In Study 1, children with ASD were as accurate at disambiguating the meanings of novel words from statistical correspondences as TD controls matched on receptive vocabulary. In Study 2, both populations spontaneously utilised social and non-social attentional cues to facilitate and accelerate their mapping of word-referent relationships. Across Studies 1 and 2, both groups retrieved and generalised word-referent representations with impressive and comparable accuracy. Although children with ASD performed very similarly to TD children on measures of learning accuracy, they were significantly slower to identify correct referents under both cued and non-cued learning conditions. These findings indicate that mechanisms supporting cross-situational word learning, and the relationships between them, are not qualitatively atypical in language-delayed children with ASD. However, the increased time required to generate correct responses suggests that these mechanisms may be less efficient, potentially impacting learning in natural environments where visual and auditory stimuli are presented rapidly. Our data support claims that word learning in the longer term is driven by the gradual accumulation of word-object associations over multiple learning instances and could potentially inform the development of interventions designed to scaffold word learning.