Measuring child personality when child personality was not measured: Application of a thin-slice approach.

Recent efforts have demonstrated that thin-slice (TS) assessment-or assessment of individual characteristics after only brief exposure to that individual's behaviour-can produce reliable and valid measurements of child personality traits. The extent to which this approach can be generalized to archival data not designed to measure personality, and whether it can be used to measure personality pathology traits in youth, is not yet known. Archival video data of a parent-child interaction task was collected as part of a clinical intervention trial for aggressive children (N = 177). Unacquainted observers independently watched the clips and rated children on normal-range (neuroticism, extraversion, agreeableness, conscientiousness and openness to experience) and pathological (callous-unemotional) personality traits. TS ratings of child personality showed strong internal consistency, valid associations with measures of externalizing problems and temperament, and revealed differentiated subgroups of children based on severity. As such, these findings demonstrate an ecologically valid application of TS methodology and illustrate how researchers and clinicians can extend their existing data by measuring child personality using TS methodology, even in cases where child personality was not originally measured. Copyright © 2016 John Wiley & Sons, Ltd.