Only true and fabricated baseline statements combined might improve lie, but not truth, detection.

Objectives: We tested the effect of true and fabricated baseline statements from the same sender on veracity judgments.

Hypotheses: We predicted that presenting a combination of true and fabricated baseline statements would improve truth and lie detection accuracy, while presenting a true baseline would improve only truth detection, and presenting a fabricated baseline would only improve lie detection compared with presenting no baseline statement.

Method: In a 4 × 2 within-subjects design, 142 student participants ( = 23.47 years; 118 female) read no baseline statement, a true baseline statement, a fabricated baseline statement, and a combination of a true and a fabricated baseline statement from 29 different senders. Participants then rated the veracity of a true or fabricated target statement from the same 29 senders.

Results: Logistic mixed-effects models with senders and participants as random effects showed no significant differences in overall veracity judgment accuracy between the no-baseline (51%) and either the true-baseline (44%) or the fabricated-baseline (49%) conditions. Equivalence tests failed to show the predicted equivalence of these accuracy rates. Separate analyses of truth and lie detection rates confirmed the assumed improvement of lie detection in the combination-of-true-and-fabricated-baseline condition (accuracy = 39%-61%). No other truth or lie detection rate changed significantly except that, unexpectedly, a true baseline reduced truth detection accuracy (64%-49%).

Conclusions: Baseline statements largely did not affect judgment accuracy and, in the case of true baselines, even had a negative impact on truth detection. The rather small positive effect of two baseline statements on lie detection suggests an avenue for further research, especially with expert raters. (PsycInfo Database Record (c) 2022 APA, all rights reserved).