Using Developmental Trajectories to Understand Developmental DisordersPurpose: In this article, the authors present a tutorial on the use of developmental trajectories for studying language and cognitive impairments in developmental disorders and compare this method with the use of matching. Method: The authors assess the strengths, limitations, and practical implications of each method. The contrast between the methodologies is highlighted using the example of developmental delay and the criteria used to distinguish delay from atypical development. Results: The authors argue for the utility of the trajectory approach, using illustrations from studies investigating language and cognitive impairments in individuals with Williams syndrome, Down syndrome, and autism spectrum disorder. Conclusion: Two conclusions were reached: (a) An understanding of the underlying mechanism will be furthered by the richer descriptive vocabulary provided by the trajectories approach (e.g., in distinguishing different types of delay) and (b) an optimal design for studying developmental disorders is to combine initial cross-sectional designs with longitudinal follow-up.

These findings point to both delay and deviance in WS face processing and illustrate how vital it is to build developmental trajectories for each specific task.

One of the most noticeable problems in autism involves the social use of language such as metaphor and metonymy, both of which are very common in daily language use. The present study is the first to investigate the development of metaphor and metonymy comprehension in autism. Eleven children with autism were compared to 17 typically developing children in a metaphor-metonymy comprehension task. Cross-sectional trajectory analyses were used to compare the development of metaphor and metonymy comprehension using a child-friendly story picture task. Trajectories were constructed linking task performance either to chronological age or to measures of mental age. Children with autism showed an impaired metaphor comprehension in relation to both chronological and mental age, whereas performance on metonymy was delayed and in line with their receptive vocabulary. Our results suggest that understanding of metaphors and metonyms are severely affected at all ages examined in the current study.

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Children with cerebral palsy have more sleep problems than typically developing peers. Their mothers also have disturbed sleep that correlates with maternal depression. Childhood sleep problems can be treated and should be identified in routine clinical practice.

Parents report universal sleep problems in school aged children with Down syndrome. Paediatricians should routinely enquire about sleep behaviour in these children.

Preferential attention to biological motion can be seen in typically developing infants in the first few days of life and is thought to be an important precursor in the development of social communication. We examined whether children with autism spectrum disorder (ASD) aged 3-7 years preferentially attend to point-light displays depicting biological motion. We found that children with ASD did not preferentially attend to biological motion over phase-scrambled motion, but did preferentially attend to a point-light display of a spinning top rather than a human walker. In contrast a neurotypical matched control group preferentially attended to the human, biological motion in both conditions. The results suggest a core deficit in attending to biological motion in ASD.

Recent findings suggest that children with autism may be impaired in the perception of biological motion from moving point-light displays. Some children with autism also have abnormally high motion coherence thresholds. In the current study we tested a group of children with autism and a group of typically developing children aged 5 to 12 years of age on several motion perception tasks, in order to establish the specificity of the biological motion deficit in relation to other visual discrimination skills. The first task required the recognition of biological from scrambled motion. Three quasi-psychophysical tasks then established individual thresholds for the detection of biological motion in dynamic noise, of motion coherence and of form-from-motion. Lastly, individual thresholds for a task of static perception--contour integration (Gabor displays)--were also obtained. Compared to controls, children with autism were particularly impaired in processing biological motion in relation to any developmental measure (chronological or mental age). In contrast, there was some developmental overlap in ability to process other types of visual motion between typically developing children and the children with autism, and evidence of developmental change in both groups. Finally, Gabor display thresholds appeared to develop typically in children with autism.