UCLA

The representation and utilization of temporal information is a basic human ability that permeates many aspects of daily life, such as estimating the duration of an event or predicting the duration of a behavioral response. The ability to discriminate temporal durations develops in infancy; however, the precision (i.e., consistency) of timing abilities improves from early childhood to adolescence. In recent years, there has been a surge of interest in the neurobiological basis of temporal processing, and the frontal-striatal systems have been implicated in second-range timing functions. Frontal-striatal abnormalities are well documented in attention-deficit/hyperactivity disorder (ADHD), autism spectrum disorders (ASD), and the genetic syndrome resulting from a deletion at 22q11.2 (22q11DS); therefore, temporal processing is a candidate endophenotype that may serve as a clinical indicator of aberrant frontal-striatal function. The purpose of this study was to: (1) characterize time reproduction accuracy and variability in three different neurodevelopmental disorders, (2) model age-related changes in time reproduction accuracy and consistency, and (3) assess the relative contributions of symptom dimensions (inattention, hyperactivity, and autistic traits) to time reproduction performance. Data were collected over a three year period as an adjunct to ongoing research studies in ADHD, ASD, and 22q11DS. The time reproduction task was a previously validated measure of interval timing with target durations of 4, 8, 12, 16, and 20 seconds repeated four times each in random order. Time reproduction accuracy and consistency were analyzed separately in each of the three samples using repeated measures mixed effects regression. Across all samples, younger age was the most consistent predictor of time reproduction variability. High levels of inattention in the ADHD group were also associated with increased variability. Both the ASD and 22q11DS groups showed evidence of increased response variability relative to typically developing comparison groups; however, in the ASD group the effect of diagnosis was moderated by working memory. The results have implications for empirical investigations of temporal processing across multiple dimensions of psychopathology and highlight the importance of considering both response variability and developmental factors (e.g., maturation of frontal-striatal circuits) in the formation of new theories linking neurobiological substrates to the emergence of symptom constellations.