Our results indicate that delays in adaptive skills for young children on the autism spectrum can be observed as early as two years of age. Five of the ten Vineland-II v-scale sample means were at least 1.5 standard deviations below the standardization sample mean.
We found a group profile of Vineland-II standard scores in which Motor Skills > Daily Living Skills > Socialization > Communication for this sample of toddlers on the autism spectrum. Past research examining profiles of adaptive behavior for individuals on the autism spectrum has produced somewhat inconsistent results (e.g., Carter et al., 1998
; Fenton et al., 2003
; Perry et al., 2009
), partially due to the use of samples of varying ages and cognitive levels. Varying amounts and types of intervention services received across samples could also contribute to the inconsistent results (e.g., the vast majority of our participants were not receiving an intensive amount of intervention at the time of data collection). However, prior research has shown that, as a group, children on the autism spectrum tend to demonstrate lower scores in the Socialization and Communication domains compared to age- and MA-matched, non-spectrum children with intellectual disabilities (e.g., Loveland & Kelley, 1991
; Perry et al., 2009
). Although an individual's adaptive behavior score profile should not be used as a diagnostic heuristic, the presence of a characteristic group profile on the Vineland-II contributes to our understanding of the relative parent-reported strengths and weaknesses in adaptive skills found among toddlers on the autism spectrum. With a general emphasis being placed on early diagnosis, these findings may have utility in differential diagnoses as one piece of information in the context of a comprehensive diagnostic evaluation.
Our findings demonstrated that Vineland-II and Bayley-III Cognitive scores were significantly correlated for our sample using both domain standard scores and subdomain v
-scale scores. As noted by Brassard and Boehm (2007)
, the Bayley-III Cognitive standard scores have an absolute floor of 55, which may limit score variability among toddlers with significant cognitive delays. Although none of our participants obtained a score of 55, it is possible that our sample mean Cognitive standard score of 85 may have been lower if the instrument had a lower floor.
Calibrated ADOS scores were significantly negatively correlated with Bayley-III Cognitive standard scores and with standard scores in the Daily Living Skills and Communication domains of the Vineland-II. For toddlers on the autism spectrum, the negative correlation between ADOS and Bayley-III scores may be influenced by the presence of restricted and repetitive behaviors that may interfere with performance on developmental testing or reduced engagement in some of the Bayley-III tasks that require imitation, demonstration of pretend play skills, and interaction with the examiner.
Interestingly, there was not a significant association between calibrated ADOS scores and Socialization scores on the Vineland-II. This may be due to the nature of the Socialization domain items for young children, which assess some skills that are not covered on the ADOS (e.g., play interactions with other children), or differences between parents' perceptions of their child's social skills and an examiner's observations during a specific, semi-structured assessment. As pointed out by one of the anonymous reviewers of this article, it may also be possible that parents or caregivers may not recognize and report the extent to which they modify the child's environment to minimize the impact of the child's impairments.
We did not find that calibrated ADOS scores contributed additional variance to Vineland-II scores beyond that predicted by age and Bayley-III Cognitive standard scores. This result was in contrast to the findings of Perry and colleagues (2009)
, although their study used the CARS to measure characteristics of autism and the original VABS. Additionally, their sample included children up to 6 years of age. Replication studies will be necessary to determine whether calibrated ADOS scores generally contribute to the variance in adaptive behavior for young children on the autism spectrum. Our study examined adaptive behavior and cognitive skills for toddlers on the autism spectrum and, as such, the results should not be generalized to other age groups.
A limitation of this study is that identifying group profiles on measures such as the Vineland-II does not reveal within-group variance. Although typical profiles can contribute to our general understanding of group characteristics, it is also important to acknowledge that a range of individual differences may be present within a group on a given measure.
Conclusions and Future Directions
This study demonstrated that delays in adaptive skills for toddlers on the autism spectrum are evident using the recently updated Vineland-II. A Vineland-II group profile was found which suggests a relative weakness in parent-reported social and communication skills for these young children. Calibrated ADOS scores also appear to be negatively correlated with performance on the Bayley-III, although their association with adaptive behavior is less clear.
Future research should examine Vineland-II adaptive behavior profiles for older children on the autism spectrum to identify possible age-related patterns on this recently updated instrument. Similarly, this revised measure can be used in comparison with cognitive measures other than the Bayley-III, such as those that offer full-scale IQ scores. There is also a need for further research replicating the work of Gotham et al. (2009)
and examining relationships between calibrated ADOS scores and other measures of functioning. Research examining predictors of growth in adaptive skill levels during early childhood could also be useful for clinical applications, such as intervention planning and progress monitoring.