Verbal Baselining: Within-Subject Consistency of CBCA Scores across Different Truthful and Fabricated Accounts

Abstract

Statement Validity Assessment (SVA) proposes that baseline statements on different events can serve as a within-subject measure of a witness’ individual verbal capabilities when evaluating scores from Criteria-based Content Analysis (CBCA). This assumes that CBCA scores will generally be consistent across two accounts by the same witness. We present a first pilot study on this assumption. In two sessions, we asked 29 participants to produce one experience-based and one fabricated baseline account as well as one experience-based and one fabricated target account (each on different events), resulting in a total of 116 accounts. We hypothesized at least moderate correlations between target and baseline indicating a consistency across both experience-based and fabricated CBCA scores, and that fabricated CBCA scores would be more consistent because truth-telling has to consider random event characteristics, whereas lies must be constructed completely by the individual witness. Results showed that differences in correlations between experience-based CBCA scores and between fabricated CBCA scores took the predicted direction (cexperience-based = .44 versus cfabricated =.61) but this difference was not statistically significant. As predicted, a subgroup of event-related CBCA criteria were significantly less consistent than CBCA total scores, but only in experience-based accounts. The discussion considers methodological issues regarding the usage of total CBCA scores and whether to measure consistency with correlation coefficients. It is concluded that more studies are needed with larger samples.