Mismatches in premises and conclusion affect deductive reasoning: a tDCS-ERP study

Abstract

This study aimed to examine the interfering effect of mismatches on deductive reasoning, measured both behaviorally and through event-related potentials (ERP), and whether anodal transcranial direct current stimulation (tDCS) applied to the left prefrontal cortex (PFC) reduces this effect.Materials and Methods: This study involved 27 healthy right-handed participants, including 11 women, with a mean age of 27.21 ± 6.76 years. Anodal stimulation was applied to the left PFC, while a cathode was placed on the right mastoid. All participants completed inference tasks under both sham and anodal stimulation conditions. Within-group comparisons were conducted to analyze behavioral performance and ERP recordings, which were compared between the sham and anodal stimulation conditions.Results: The results showed that the response rate for deductive inference tasks with the highest levels of mismatch significantly increased after anodal stimulation compared to sham stimulation. However, there was no significant difference in reaction times between the two stimulation methods. Notably, the highest N2 wave in the frontal region was observed during tasks with the greatest level of mismatch. However, no significant differences in N2 amplitude or latency associated with anodal stimulation were detected.Conclusion: The findings of the study indicated that anodal tDCS has a limited effect on inference tasks that involve different levels of mismatch. This may be due to a ceiling effect caused by selecting a relatively simple form of inference due to the control of confounding variables.