With the growing number of children who receive a diagnosis of Autism Spectrum Disorder (ASD), there is an increasing need to identify risk markers that will allow for earlier diagnosis of this disorder. Since no single atypical behavior has been found that is shared by all 12-month-old infants who are later diagnosed with ASD, it is likely that a constellation of markers combine in a way that is more predictive of outcome at this age. Establishing a Cumulative Risk Index (CRI) is one way to investigate which combination of early risk markers is most predictive of later ASD diagnostic outcome. Temperament is one construct of behavior that could act as an early risk marker for ASD and therefore, could add predictive power to a CRI for this disorder. Temperament is defined as a "behavioral style" that includes individual differences in reactivity and self-regulation and emphasizes emotional, attentional and activity related characteristics. Another important aspect of temperament is that it exerts bidirectional influences upon the social environment. Therefore, the study of temperament could provide a method for understanding how children with ASD influence and are influenced by the environment of a testing session. Though important information has been collected about early temperament in children with ASD, much of the data is limited due to its dependence on retrospective and parent-report measures. One measure that allows for direct assessment of temperament during a controlled testing session is the Infant Behavior Record (IBR). The purpose of this study is to investigate early temperament in ASD by using the IBR as an assessment of temperament behaviors in high-risk 12-month old infants. Through this, we hope to reveal group differences in IBR scores, establish a relationship between temperament scores and cognitive test performance, and increase predictive value of the CRI when IBR scores are included. For this study, a revised version of the IBR was filled out while watching video record of the administration of the Mullen Scales of Early Learning (MSEL) at an infant's 12-month lab visit. Scores for the IBR reflected the examiner's impressions of the infant's orientation to objects and people and emotional state. Through using the IBR to study task orientation (TO), affect/extraversion (AE) and activity level (AL) in high-risk infants, this study found that only decreased AE behaviors distinguished high-risk infants who went on to develop ASD (HRA+ASD) from high-risk infants who did not receive an ASD diagnosis (HRA-ASD) (p=.08). To determine the relationship of temperament and cognitive assessment performance, IBR scores were compared to MSEL scores. This study found that across all participants, TO and AE behaviors were positively correlated with MSEL scores (AE rs=.27, p<.001; TO rs=.37, p<.001). This relationship remained true for both the high-risk (AE rs=.20, p<.001; TO rs=.23, p<.001) and the low risk groups (AE rs=.32, p<.001; TO rs=.54, p<.001), as well as for the HRA-ASD infants (AE, trend, p=.057; rs=.24, p<.001; TO rs=.459, p<.001), and the low-risk infants who did not go on to receive a diagnosis of ASD (AE rs=.35, p<.001; TO rs=.47, p<.001). The only group in this study that was found to have no correlations between temperament scores and MSEL scores was HRA+ASD. Since only AE behaviors distinguished HRA+ASD infants, this was the only IBR factor added to a pilot model of the CRI. This study found that the inclusion of AE to a pilot model of the CRI did not add significant predictive value to the model (p=.15). Through using the IBR to investigate temperament in HRA infants, the findings of this study suggest that there are some important differences in temperament behaviors for HRA+ASD infants. Specifically, reduced AE behaviors seem to distinguish the HRA+ASD infants from the other outcome groups. Also, this study found that increased TO and AE behaviors were associated with better performance on a cognitive assessment for all groups except HRA+ASD. These two findings are important, as they differentiate this outcome group from all others, suggesting that there may be a different set of mechanisms employed during a testing session for HRA+ASD infants. This study also found that AE risk did not contribute predictive value to a CRI for this disorder. Taken together these findings suggest that though temperament profiles appear to differ in HRA+ASD infants during the first year of life, this construct of behavior is not a valuable early behavioral risk marker for identifying ASD.

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