To begin to delineate the psychological characteristics associated with classic 7q11.23 duplication syndrome (duplication of the classic Williams syndrome region; hereafter classic Dup7), we tested 63 children with classic Dup7 aged 4–17 years. Sixteen toddlers aged 18–45 months with classic Dup7 and 12 adults identified by cascade testing also were assessed. For the child group, median General Conceptual Ability (similar to IQ) on the Differential Ability Scales-II was 85.0 (low average), with a range from severe disability to high average ability. Median reading and mathematics achievement standard scores were at the low average to average level, with a range from severe impairment to high average or superior ability. Adaptive behavior was considerably more limited; median Scales of Independent Behavior—Revised Broad Independence standard score was 62.0 (mild impairment), with a range from severe adaptive impairment to average adaptive ability. Anxiety disorders were common, with 50.0% of children diagnosed with Social Phobia, 29.0% with Selective Mutism, 12.9% with Separation Anxiety Disorder, and 53.2% with Specific Phobia. In addition, 35.5% were diagnosed with Attention Deficit/Hyperactivity Disorder and 24.2% with Oppositional Defiant Disorder or Disruptive Behavior Disorder-Not Otherwise Specified. 33.3% of the children screened positive for a possible Autism Spectrum Disorder and 82.3% were diagnosed with Speech Sound Disorder. We compare these findings to previously reported results for children with Williams syndrome and argue that genotype/phenotype studies involving the Williams syndrome region offer important opportunities to understand the contribution of genes in this region to common disorders affecting the general population.

To examine longitudinal trajectories of intellectual abilities, single-word vocabulary abilities, and adaptive behavior for 76 children with Williams syndrome (WS) aged 4 – 15 years, we compared their standard scores (SSs) at two time points approximately 3 years apart on the same standardized measures. At the group level, mean SS declined significantly for 8 of the 12 measures and showed a slight (nonsignificant) increase or decrease for 4 measures. However, for most measures significant changes in SS were found for only a small proportion of the children, with some children evidencing significant declines and a smaller proportion evidencing significant increases. Significant SS changes were most common for adaptive behavior. For all measures, the mean magnitude of SS change was smaller for older children (> 7.5 years at Time 1) than for younger children (< 7.5 years at Time 1). Furthermore, correlations between Time 1 and Time 2 SSs were larger for the older cohort than for the younger cohort, indicating that SS stability was greater for older children than for younger children. Although mean SSs declined for most measures, indicating that children with WS as a group were not making the expected amount of progress relative to their general population peers who earned the same SS at Time 1, there was little evidence either of regression (loss of skills) or stagnation (failure to increase raw scores). The relations of these results to those of previous smaller-sample longitudinal studies of children with WS and the implications of the findings are considered.

Visual acuity and contrast sensitivity progressively diminish with increasing viewing eccentricity. Here we evaluated how visual enumeration is affected by visual eccentricity, and whether subitizing capacity, the accurate enumeration of a small number (∼3) of items, decreases with more eccentric viewing. Participants enumerated gratings whose (1) stimulus size was constant across eccentricity, and (2) whose stimulus size scaled by a cortical magnification factor across eccentricity. While we found that enumeration accuracy and precision decreased with increasing eccentricity, cortical magnification scaling of size neutralized the deleterious effects of increasing eccentricity. We found that size scaling did not affect subitizing capacities, which were nearly constant across all eccentricities. We also found that size scaling modulated the variation coefficients, a normalized metric of enumeration precision, defined as the standard deviation divided by the mean response. Our results show that the inaccuracy and imprecision associated with increasing viewing eccentricity is due to limitations in spatial resolution. Moreover, our results also support the notion that the precise number system is restricted to small numerosities (represented by the subitizing limit), while the approximate number system extends across both small and large numerosities (indexed by variation coefficients) at large eccentricities.

Background Specific phobia (SP) is the most common anxiety disorder among children with Williams syndrome (WS); prevalence rates derived from DSM-based diagnostic interviews range from 37% – 56%. We evaluated the effects of gender, age, intellectual abilities, and/or behaviour regulation difficulties on the likelihood that a child with WS would be diagnosed with SP. Methods 194 6 – 17-year-olds with WS were evaluated. To best characterize the relations between the predictors and the probability of a SP diagnosis, we explored not only possible linear effects but also curvilinear effects. Results No gender differences were detected. As age increased, the likelihood of receiving a SP diagnosis decreased. As IQ increased, the probability of receiving a SP diagnosis also decreased. Behaviour regulation difficulties were the strongest predictor of a positive diagnosis. A quadratic relation was detected: The probability of receiving a SP diagnosis gradually rose as behaviour regulation difficulties increased. However, once behaviour regulation difficulties approached the clinical range, the probability of receiving a SP diagnosis asymptoted at a high level. Conclusion Children with behaviour regulation difficulties in or just below the clinical range were at the greatest risk of developing SP. These findings highlight the value of large samples and the importance of evaluating for nonlinear effects to provide accurate model specification when characterizing relations among a dependent variable and possible predictors.

We describe the performance of 292 4 – 17-year-olds with Williams syndrome (WS) on the Kaufman Brief Intelligence Test-2 (KBIT-2). Mean IQ Composite, Verbal standard score (SS), and Nonverbal SS were in the borderline range relative to the general population, with variability similar to the general population. Correlations between SSs and CA were close to 0, with no significant sex differences. There was a significant effect of maternal education on Verbal SS. The KBIT-2 appropriately captures the full range of performance of 8 – 17-year-olds with WS for the abilities measured and of all but the very lowest-functioning 5 – 7-year-olds. However, the KBIT-2 does not contain easy enough items to assess adequately the abilities of the lowest quartile of 4-year-olds.