Jon Brock

Language abilities in Williams syndrome: A critical review

Williams syndrome is a rare genetic disorder in which, it is claimed, language abilities are relatively strong despite mild to moderate mental retardation. Such claims have, in turn, been interpreted as evidence either for modular preservation of language or for atypical constraints on cognitive development. However, this review demonstrates that there is, in fact, little evidence that syntax, morphology, phonology, or pragmatics are any better than predicted by nonverbal ability, although performance on receptive vocabulary tests is relatively good. Similarly, claims of an imbalance between good phonology and impaired or atypical lexical semantics are without strong support. There is, nevertheless, consistent evidence for specific deficits in spatial language that mirror difficulties in nonverbal spatial cognition, as well as some tentative evidence that early language acquisition proceeds atypically. Implications for modular and neuroconstructivist accounts of language development are discussed.

Eye-movement patterns are associated with communicative competence in autistic spectrum disorders

BACKGROUND Investigations using eye-tracking have reported reduced fixations to salient social cues such as eyes when participants with autism spectrum disorders (ASD) view social scenes. However, these studies have not distinguished different cognitive phenotypes. METHODS The eye-movements of 28 teenagers with ASD and 18 typically developing peers were recorded as they watched videos of peers interacting in familiar situations. Within ASD, we contrasted the viewing patterns of those with and without language impairments. The proportion of time spent viewing eyes, mouths and other scene details was calculated, as was latency of first fixation to eyes. Finally, the association between viewing patterns and social-communicative competence was measured. RESULTS Individuals with ASD and age-appropriate language abilities spent significantly less time viewing eyes and were slower to fixate the eyes than typically developing peers. In contrast, there were no differences in viewing patterns between those with language impairments and typically developing peers. Eye-movement patterns were not associated with social outcomes for either language phenotype. However, increased fixations to the mouth were associated with greater communicative competence across the autistic spectrum. CONCLUSIONS Attention to both eyes and mouths is important for language development and communicative competence. Differences in fixation time to eyes may not be sufficient to disrupt social competence in daily interactions. A multiple cognitive deficit model of ASD, incorporating different language phenotypes, is advocated.

Do individuals with autism process words in context? Evidence from language-mediated eye-movements

It is widely argued that people with autism have difficulty processing ambiguous linguistic information in context. To investigate this claim, we recorded the eye-movements of 24 adolescents with autism spectrum disorder and 24 language-matched peers as they monitored spoken sentences for words corresponding to objects on a computer display. Following a target word, participants looked more at a competitor object sharing the same onset than at phonologically unrelated objects. This effect was, however, mediated by the sentence context such that participants looked less at the phonological competitor if it was semantically incongruous with the preceding verb. Contrary to predictions, the two groups evidenced similar effects of context on eye-movements. Instead, across both groups, the effect of sentence context was reduced in individuals with relatively poor language skills. Implications for the weak central coherence account of autism are discussed.

Alternative Bayesian accounts of autistic perception: comment on Pellicano and Burr

Atypical sensory-perceptual experiences are a widely acknowledged, but poorly understood feature of autism. An enduring and still unresolved question is whether autistic perception should best be characterized in terms of reduced top-down influences on perception or, alternatively, enhanced bottom-up sensory-perceptual processes [1,2]. In their recent Opinion article, Pellicano and Burr [3] argue for the former. Their ‘hypo-priors’ account of autistic perception is essentially a Bayesian formalization of Mitchell and Ropars earlier suggestion of ‘attenuated influence by prior knowledge’ [4].

Do Children with Williams Syndrome Really Have Good Vocabulary Knowledge? Methods for Comparing Cognitive and Linguistic Abilities in Developmental Disorders.

The comparison of cognitive and linguistic skills in individuals with developmental disorders is fraught with methodological and psychometric difficulties. In this paper, we illustrate some of these issues by comparing the receptive vocabulary knowledge and non‐verbal reasoning abilities of 41 children with Williams syndrome, a genetic disorder in which language abilities are often claimed to be relatively strong. Data from this group were compared with data from typically developing children, children with Down syndrome, and children with non‐specific learning difficulties using a number of approaches including comparison of age‐equivalent scores, matching, analysis of covariance, and regression‐based standardization. Across these analyses children with Williams syndrome consistently demonstrated relatively good receptive vocabulary knowledge, although this effect appeared strongest in the oldest children.

Attention to social stimuli and facial identity recognition skills in autism spectrum disorder

BACKGROUND Previous research suggests that individuals with autism spectrum disorder (ASD) have a reduced preference for viewing social stimuli in the environment and impaired facial identity recognition. METHODS Here, we directly tested a link between these two phenomena in 13 ASD children and 13 age-matched typically developing (TD) controls. Eye movements were recorded while participants passively viewed visual scenes containing people and objects. Participants also completed independent matching tasks for faces and objects. RESULTS AND CONCLUSIONS Behavioural data showed that participants with ASD were impaired on both face- and object-matching tasks relative to TD controls. Eye-tracking data revealed that both groups showed a strong bias to orient towards people. TD children spent proportionally more time looking at people than objects; however, there was no difference in viewing times between people and objects in the ASD group. In the ASD group, an individuals preference for looking first at the people in scenes was associated with level of face recognition ability. Further research is required to determine whether a causal relationship exists between these factors.

Specificity of impaired facial identity recognition in children with suspected developmental prosopagnosia

Adults experiencing face recognition difficulties in the absence of known brain injury are described as cases of developmental prosopagnosia (DP), under the assumption that specific face recognition impairments have always been present. However, only five childhood cases of DP have been reported, and the majority had additional socio-communicative impairments consistent with an autism spectrum disorder (ASD). We tested face recognition skills of six 4- to 8-year-old children, who were suspected of having DP, and tested for ASD using established diagnostic tools. Two children met criteria for ASD. One child did not exhibit consistent face recognition impairments. The remaining three children were severely impaired on multiple tasks of unfamiliar face recognition despite normal cognitive functioning and no evidence of ASD. Two of these children were also impaired at object recognition suggesting more general visual recognition problems. The final child showed normal object recognition demonstrating apparently specific problems with facial identity recognition.

Lateralized auditory brain function in children with normal reading ability and in children with dyslexia

We examined central auditory processing in typically- and atypically-developing readers. Concurrent EEG and MEG brain measurements were obtained from a group of 16 children with dyslexia aged 8-12 years, and a group of 16 age-matched children with normal reading ability. Auditory responses were elicited using 500ms duration broadband noise. These responses were strongly lateralized in control children. Children with dyslexia showed significantly less lateralisation of auditory cortical functioning, and a different pattern of development of auditory lateralization with age. These results provide further evidence that the core neurophysiological deficit of dyslexia is a problem in the balance of auditory function between the two hemispheres.

A frontotemporoparietal network common to initiating and responding to joint attention bids

Joint attention is a fundamental cognitive ability that supports daily interpersonal relationships and communication. The Parallel Distributed Processing model (PDPM) postulates that responding to (RJA) and initiating (IJA) joint attention are predominantly supported by posterior-parietal and frontal regions respectively. It also argues that these neural networks integrate during development, supporting the parallel processes of self- and other-attention representation during interactions. However, direct evidence for the PDPM is limited due to a lack of ecologically valid experimental paradigms that can capture both RJA and IJA. Building on existing interactive approaches, we developed a virtual reality paradigm where participants engaged in an online interaction to complete a cooperative task. By including tightly controlled baseline conditions to remove activity associated with non-social task demands, we were able to directly contrast the neural correlates of RJA and IJA to determine whether these processes are supported by common brain regions. Both RJA and IJA activated broad frontotemporoparietal networks. Critically, a conjunction analysis identified that a subset of these regions were common to both RJA and IJA. This right-lateralised network included the dorsal portion of the middle frontal gyrus (MFG), inferior frontal gyrus (IFG), middle temporal gyrus (MTG), precentral gyrus, posterior superior temporal sulcus (pSTS), temporoparietal junction (TPJ) and precuneus. Additional activation was observed in this network for IJA relative to RJA at MFG, IFG, TPJ and precuneus. This is the first imaging study to directly investigate the neural correlates common to RJA and IJA engagement, and thus support the assumption that a broad integrated network underlies the parallel aspects of both initiating and responding to joint attention.

Individual differences in visual search: relationship to autistic traits, discrimination thresholds, and speed of processing

Enhanced visual search is widely reported in autism. Here we note a similar advantage for university students self-reporting higher levels of autism-like traits. Contrary to prevailing theories of autism, performance was not associated with perceptual-discrimination thresholds for the same stimuli, but was associated with inspection-time threshold—a measure of speed of perceptual processing. Enhanced visual search in autism may, therefore, at least partially be explained by faster speed of processing.