The impact of reducing cognitive load in RT and P300 concealed information tests with importance related fillers

Lukács et al. (2017) enhanced the Reaction Time Concealed Information Test (RT CIT) by incorporating "filler" items. Fillers are intended to increase attention and cognitive load, which should potentially enhance the P300 based CIT (P300-CIT) too. Despite these hypotheses, Olson et al. (2020) found no clear effects of fillers on P300 amplitude and suggested that excessive cognitive load may counteract an increase in attention. Wojciechowski and Lukács (2022) introduced "importance-related" fillers to the RT-CIT in an imaginary mock crime scenario, theorizing they would be more intuitive and easier for participants to follow. This study aims to replicate their findings in a classic episodic mock crime scenario, and with semantic information, to test if a fillers-related enhancement effect on P300 may be observed when cognitive load is reduced. The study compares three protocols: the importance-themed enhanced CIT (E-CIT), a less cognitively demanding version of the E-CIT, the inducer CIT (I-CIT), and the classic three-stimulus protocol (3SP-CIT). The study investigates whether the I-CIT yields a superior P300-CIT effect due to reduced cognitive load and induced semantic context of importance. Reaction time analyses replicated the RT-CIT effect enhancement in the E-CIT compared to the classic 3SP-CIT. Elevated response times in the E-CIT compared to the 3SP-CIT and I-CIT suggest higher cognitive load in the E-CIT. Response times were comparable between the 3SP-CIT and I-CIT, suggesting similar cognitive load. For the P300-CIT results, similar to Olson et al. (2020), fillers did not affect P300 amplitude or latency in the E-CIT group, with Bayes factors supporting the null. Contrary to expectations, no clear enhancement of P300 was observed in the I-CIT, suggesting that cognitive load imposed by fillers does not counteract P300 amplitude.