Memory, learning and language in autism spectrum disorder

Background and aims: The ‘dual-systems’ model of language acquisition has been used by Ullman and colleagues to explain patterns of strength and weakness in the language of higher-functioning people with autism spectrum disorder (ASD). Specifically, intact declarative/explicit learning is argued to compensate for a deficit in non-declarative/implicit procedural learning, constituting an example of the so-called ‘see-saw’ effect. Ullman and Pullman (2015) extended their argument concerning a see-saw effect on language in ASD to cover other perceived anomalies of behaviour, including impaired acquisition of social skills. The aim of this paper is to present a critique of Ullman and colleagues’ claims, and to propose an alternative model of links between memory systems and language in ASD. Main contribution: We argue that a 4-systems model of learning, in which intact semantic and procedural memory are used to compensate for weaknesses in episodic memory and perceptual learning, can better explain patterns of language ability across the autistic spectrum. We also argue that attempts to generalise the ‘impaired implicit learning/spared declarative learning’ theory to other behaviours in ASD are unsustainable. Conclusions: Clinically significant language impairments in ASD are under-researched, despite their impact on everyday functioning and quality of life. The relative paucity of research findings in this area lays it open to speculative interpretation which may be misleading. Implications: More research is need into links between memory/learning systems and language impairments across the spectrum. Improved understanding should inform therapeutic intervention, and contribute to investigation of the causes of language impairment in ASD with potential implications for prevention

ERP Correlates of Recognition Memory in Autism Spectrum Disorder

Recognition memory in autism spectrum disorder (ASD) tends to be undiminished compared to that of typically developing (TD) individuals (Bowler et al. 2007), but it is still unknown whether memory in ASD relies on qualitatively similar or different neurophysiology. We sought to explore the neural activity underlying recognition by employing the old/new word repetition event-related potential effect. Behavioural recognition performance was comparable across both groups, and demonstrated superior recognition for low frequency over high frequency words. However, the ASD group showed a parietal rather than anterior onset (300–500 ms), and diminished right frontal old/new effects (800–1500 ms) relative to TD individuals. This study shows that undiminished recognition performance results from a pattern of differing functional neurophysiology in ASD

Sex differences in brain plasticity: a new hypothesis for sex ratio bias in autism.

Several observations support the hypothesis that differences in synaptic and regional cerebral plasticity between the sexes account for the high ratio of males to females in autism. First, males are more susceptible than females to perturbations in genes involved in synaptic plasticity. Second, sex-related differences in non-autistic brain structure and function are observed in highly variable regions, namely, the heteromodal associative cortices, and overlap with structural particularities and enhanced activity of perceptual associative regions in autistic individuals. Finally, functional cortical reallocations following brain lesions in non-autistic adults (for example, traumatic brain injury, multiple sclerosis) are sex-dependent. Interactions between genetic sex and hormones may therefore result in higher synaptic and consecutively regional plasticity in perceptual brain areas in males than in females. The onset of autism may largely involve mutations altering synaptic plasticity that create a plastic reaction affecting the most variable and sexually dimorphic brain regions. The sex ratio bias in autism may arise because males have a lower threshold than females for the development of this plastic reaction following a genetic or environmental event

Drawing firmer conclusions: autistic children show no evidence of a local processing bias in a controlled copying task

Drawing tasks are frequently used to test competing theories of visuospatial skills in autism. Yet, methodological differences between studies have led to inconsistent findings. To distinguish between accounts based on local bias or global deficit, we present a simple task that has previously revealed dissociable local/global impairments in neuropsychological patients. Autistic and typical children copied corner elements, arranged in a square configuration. Grouping cues were manipulated to test whether global properties affected the accuracy of reproduction. All children were similarly affected by these manipulations. There was no group difference in the reproduction of local elements, although global accuracy was negatively related to better local processing for autistic children. These data speak against influential theories of visuospatial differences in autism

The relationship between sensory sensitivity and autistic traits in the general population.

Individuals with Autism Spectrum Disorders (ASDs) tend to have sensory processing difficulties (Baranek et al. in J Child Psychol Psychiatry 47:591–601, 2006). These difficulties include over- and under-responsiveness to sensory stimuli, and problems modulating sensory input (Ben-Sasson et al. in J Autism Dev Disorders 39:1–11, 2009). As those with ASD exist at the extreme end of a continuum of autistic traits that is also evident in the general population, we investigated the link between ASD and sensory sensitivity in the general population by administering two questionnaires online to 212 adult participants. Results showed a highly significant positive correlation (r = .775, p < .001) between number of autistic traits and the frequency of sensory processing problems. These data suggest a strong link between sensory processing and autistic traits in the general population, which in turn potentially implicates sensory processing problems in social interaction difficulties

A comparison of the development of audiovisual integration in children with autism spectrum disorders and typically developing children

This study aimed to investigate the development of audiovisual integration in children with Autism Spectrum Disorder (ASD). Audiovisual integration was measured using the McGurk effect in children with ASD aged 7–16 years and typically developing children (control group) matched approximately for age, sex, nonverbal ability and verbal ability. Results showed that the children with ASD were delayed in visual accuracy and audiovisual integration compared to the control group. However, in the audiovisual integration measure, children with ASD appeared to ‘catch-up’ with their typically developing peers at the older age ranges. The suggestion that children with ASD show a deficit in audiovisual integration which diminishes with age has clinical implications for those assessing and treating these children

Impaired Competence for Pretense in Children with Autism: Exploring Potential Cognitive Predictors.

Lack of pretense in children with autism has been explained by a number of theoretical explanations, including impaired mentalising, impaired response inhibition, and weak central coherence. This study aimed to empirically test each of these theories. Children with autism (n=60) were significantly impaired relative to controls (n=65) when interpreting pretense, thereby supporting a competence deficit hypothesis. They also showed impaired mentalising and response inhibition, but superior local processing indicating weak central coherence. Regression analyses revealed that mentalising significantly and independently predicted pretense. The results are interpreted as supporting the impaired mentalising theory and evidence against competing theories invoking impaired response inhibition or a local processing bias. The results of this study have important implications for treatment and intervention

Problem Solving Styles in Autism Spectrum Disorder and the development of higher cognitive functions

The Vygotsky Blocks Test (VBT) assesses problem-solving styles within a theoretical framework for the development of higher mental processes devised by Vygotsky (Daniels et al., 2007). Because both the theory and the associated test situate cognitive development within the child's social and linguistic context, they address conceptual issues around the developmental relation between language and thought that are pertinent to development in autism. Our aim was to document the performance of adults with Autism Spectrum Disorder (ASD) on the VBT, and our results showed that they made more errors than the typically developing (TD) participants and that these errors correlated with performance IQ. The ASD group also required more cues than the TD group to discern the conceptual structure of the blocks, a pattern that correlated with ADOS Communication and Imagination/Creativity sub-scales. When asked to categorize the blocks in new ways, the ASD participants developed fewer principles on which to base new categorizations, which in contrast to the TD group, correlated with verbal IQ and with the Imagination/Creativity sub-scale of the ADOS. These results are in line with a number of existing findings in the ASD literature and confirm that conceptualization in ASD seems to rely more on non-verbal and less on imaginative processes than in TD individuals. The findings represent first steps to the possibility of outlining a testable account of psychological development in ASD that integrates verbal, non-verbal and social factors into the transition from elementary to higher-level processes

Different Verbal Learning Strategies in Autism Spectrum Disorder: Evidence from the Rey Auditory Verbal Learning Test

The Rey Auditory Verbal Learning Test, which requires the free recall of the same list of 15 items over 5 trials, was administered to a group of highfunctioning adolescents and adults with autism spectrum disorder (PDD) and a group of matched typical individuals. Overall levels of free recall were comparable in the two groups, as were the rates of learning over trials. Both groups also subjectively organised their recall to a similar extent. However, the serial position curve of the PDD participants, although similar to that of the comparison group on the first trial, became flatter on subsequent trials and was characterised by a slower growth in the primacy effect. Growth in the middle and recency portions of the curve was comparable in both groups. The findings are discussed in the light of current models of serial position effects and their implications for memory in ASD

Drawing the answers: Sketching to support free and probed recall by child witnesses and victims with autism spectrum disorder

The success of witness interviews in the criminal justice system depends on the accuracy of information obtained, which is a function of both amount and quality of information. Attempts to enhance witness retrieval such as mental reinstatement of context have been designed with typically developed adults in mind. In this paper, the relative benefits of mental and sketch reinstatement mnemonics are explored with both typically developing children and children with autism. Children watched a crime event video, and their retrieval of event information was examined in free and probed recall phases of a cognitive interview. As expected, typically developing children recalled more correct information of all types than children with autism during free and probed recall phases. Sketching during free recall was more beneficial for both groups in both phases in reducing the amount of incorrect items, but the relative effect of sketching on enhancing retrieval accuracy was greater for children with autism. The results indicate the benefits of choosing retrieval mnemonics that are sensitive to the specific impairments of autistic individuals, and suggest that retrieval accuracy during interviews can be enhanced, in some cases to the same level as that of typically developing individuals