Eye tracking as a measure of receptive vocabulary in children with autism spectrum disorders.

This study examined the utility of eye tracking research technology to measure speech comprehension in 14 young boys with autism spectrum disorders (ASD) and 15 developmentally matched boys with typical development. Using eye tracking research technology, children were tested on individualized sets of known and unknown words, identified based on their performance on the Peabody Picture Vocabulary Test. Children in both groups spent a significantly longer amount of time looking at the target picture when previous testing indicated the word was known (known condition). Children with ASD spent similar amounts of time looking at the target and non-target pictures when previous testing indicated the word was unknown (unknown condition). However, children with typical development looked longer at the target pictures in the unknown condition as well, potentially suggesting emergent vocabulary knowledge.

Pupil and salivary indicators of autonomic dysfunction in autism spectrum disorder.

Dysregulated tonic pupil size has been reported in autism spectrum disorder (ASD). Among the possible sources of this dysregulation are disruptions in the feedback loop between norepinephrine (NE) and hypothalamic systems. In the current study, we examined afternoon levels of salivary alpha-amylase (sAA, a putative correlate of NE) and cortisol (used to assess stress-based responses) in two independent samples of children with ASD. We found a larger pupil size and lower sAA levels in ASD, compared to typical and clinical age-matched controls. This was substantiated at the individual level, as sAA levels were strongly correlated with tonic pupil size. Relatively little diurnal variation in sAA taken in the home environment in the ASD group was also observed, while typical controls showed a significant linear increase throughout the day. Results are discussed in terms of potential early biomarkers and the elucidation of underlying neural dysfunction in ASD.

A Longitudinal Study of Language Trajectories and Treatment Outcomes of Early Intensive Behavioral Intervention for Autism.

The present study examined language trajectories and placement outcomes for children with autism spectrum disorder (ASD) receiving early intensive behavioral intervention (EIBI). Language measures were collected at baseline and 6, 12, 18, 24, and 36 months or until exit from EIBI in 131 children with ASD. Growth models estimated overall and subgroup language trajectories. Overall, children receiving EIBI showed substantial increases in language relative to normative expectations. Earlier age at EIBI start, higher baseline cognitive function, and lower baseline ASD severity predicted better language trajectories. Although there was significant variability in language trajectories and educational outcomes, most children showed significant increases in language scores, relative to normative expectations. Additional research, in more representative samples, is needed to understand this variability.

What Habituates in Infant Visual Habituation? A Psychophysiological Analysis.

Despite the use of visual habituation over the past half century, relatively little is known about its underlying processes. We analyzed heart rate (HR) taken simultaneous with looking during infant-controlled habituation sessions collected longitudinally at 4, 6, and 8 months of age with the goal of examining how HR and HR-defined phases of attention change across habituation. There were four major findings. First, the depth and topography of decelerations and proportion of sustained attention (SA) did not vary across habituation at any age, which suggested (in contrast to the tenets of comparator theory) the persistence of substantial cognitive activity at the end of visual habituation. Second, attention termination (AT) robustly declined across trials, suggesting that, contrary to prior thinking, AT might be a sensitive indicant of visual learning. Third, infants at all ages showed an HR increase (startle) to stimulus onset on the first trial, the magnitude of which was associated with subsequent delayed HR deceleration and less SA; thus, stimulus events affect processing during trials. Finally, mean overall HR reliably increased across trials for all ages. This last finding implies the need to distinguish between "phasic" HR changes (e.g., decelerations during looks) and longer term "tonic" HR changes (mean increases across trials) during habituation, and raises the question of what processes the tonic increases might reflect within the habituation paradigm.

Structure and Continuity of Intellectual Development in Early Childhood.

We evaluated over 200 participants semiannually from 12 to 48 months of age on measures of intellectual (Bayley Scales, Stanford-Binet Scale) and verbal (MacArthur-Bates Inventory, Peabody Picture Vocabulary Test) status. Structural equation modeling and hierarchical linear (growth curve) analyses were applied to address the nature of development and individual differences during this time. Structural analyses showed a strong and robust simplex model from infancy to the preschool period, with no evidence of qualitative reorganizations or discontinuities. Growth-curve modeling revealed significant associations between level factors across the early and later measures of cognition, providing further evidence of continuity; the growth trajectory from the Bayley through 24 months predicted growth in a nonverbal factor, but not in a verbal factor. Altogether, the findings reveal continuous and stable development in intellectual function from late infancy through the preschool years. Additionally, the high level of continuity demonstrated across these ages was observed to be largely independent of growth in vocabulary.

Larger tonic pupil size in young children with autism spectrum disorder.

The symptoms of Autism Spectrum Disorder (ASD) have been suggested to manifest from atypical functioning of the autonomic nervous system (ANS), leading to altered arousal and atypical processing of salient stimuli. Coherent with this, persons with ASD show heightened autonomic activity, sleep difficulties, and structural and neurochemical alterations within the ANS. Recently, we observed decreased pupil responses to human faces in children with ASD. In the current study, we found differences in baseline (tonic) pupil size, with the ASD group exhibiting a larger pupil size than age-matched controls. Pupil responses are sensitive and reliable measures of ANS functioning, thus, this finding highlights the role of the ANS, and may provide clues about underlying neuropathology.

Visual scanning and pupillary responses in young children with Autism Spectrum Disorder.

Using eye-tracking technology we investigated visual scanning and pupillary responses to face and non-face stimuli in nine children (M = 49.6 months) with Autism Spectrum Disorder (ASD) compared to six mental-age and nine chronological-age matched children. The results revealed a significant decrease in visual scanning to landscapes. In addition, the ASD group showed pupillary constriction to children's faces, while control groups showed pupillary dilation. Visual scanning responses to landscapes had a negative correlation with the Behavior subscale of the Autism Diagnostic Observation Schedule-Generic for the ASD group. Potential use of these measures as early indicators of ASD is discussed.

Maternal DHA and the development of attention in infancy and toddlerhood.

Infants were followed longitudinally to document the relationship between docosahexaenoic acid (DHA) levels and the development of attention. Erythrocyte (red-blood cell; RBC) phospholipid DHA (percentage of total fatty acids) was measured from infants and mothers at delivery. Infants were assessed in infant-control habituation at 4, 6, and 8 months augmented with psychophysiological measures, and on free-play attention and distractibility paradigms at 12 and 18 months. Infants whose mothers had high DHA at birth showed an accelerated decline in looking over the 1st year and increases in examining during single-object exploration and less distractibility in the 2nd year. These findings are consistent with evidence suggesting a link between DHA and cognitive development in infancy.