Tracking Concealed-Information Signatures Over Time: Passive EEG Decoding of Probe vs. Irrelevant Trials

Poster Session E - Monday, March 9, 2026, 2:30 – 4:30 pm PDT, Fairview/Kitsilano Ballrooms

Xu Peng¹ (pengxu1308@gmail.com), Yun-Wan Chen², Yu-Hui Lo¹, Philip Tseng¹; ¹Department of Psychology, National Taiwan University, Taipei, Taiwan, ²College of Medicine, Taipei Medical University, Taipei, Taiwan

ERP-based Concealed Information Test (CIT) is a robust method for detecting crime-relevant knowledge. However, ERP-CIT paradigms are vulnerable to countermeasures, partly because examinees can infer the test’s intention and strategically modulate attention or arousal to attenuate probe–irrelevant differences. To address this limitation, in this study we used sandwich-masking technique to unconsciously present the Probe and Irrelevant images while participants passively viewed the display. We quantified probe-versus-irrelevant discriminability using time-resolved EEG decoding with logistic-regression–based modeling, an analysis framework that has rarely been applied to probe–irrelevant discrimination in passive CIT settings. Statistical reliability was evaluated using one-tailed cluster-based permutation tests (p < .05) to control for family-wise error over time. We observed above-chance classification and identified five significant temporal clusters spanning 148–176 ms, 178–203 ms, 216–302 ms, 378–428 ms, and 522–548 ms. These results suggest that probe-related information becomes decodable shortly after ~150 ms and recurs across later processing stages, providing temporally specific evidence for when concealed-information signals are expressed under passive viewing. This temporal profile may refine mechanistic accounts of CIT-related neural dynamics and inform analysis-window selection in future ERP/MVPA studies.

Topic Area: PERCEPTION & ACTION: Vision