Irrelevant Emotion as Extraneous Cognitive Load modulates Relational Inductive Reasoning: Evidence from P2 and LPC

Incidental emotional states may constitute a source of extraneous cognitive load that competes with the limited cognitive resources required for reasoning, thereby impairing reasoning performance. It is still unclear whether it has the same mechanism as cognitive load in reasoning. This study employed event-related potential (ERP) technique to investigate how relational inductive reasoning was affected by incidental emotional states and intrinsic cognitive load, which were manipulated through affective priming type (neutral, positive vs. negative) and rule complexity (three rules for high load vs. one rule for low load), respectively. Thirty-five participants were recruited to identify hidden rules from an incomplete 3×3 matrix and select one of two alternatives based on the rules. Behavioral results showed that both the accuracy and RTs were affected by intrinsic cognitive load, with a significant interaction: under low load, negative and positive priming yielded higher accuracy than neutral priming, whereas under high load they yielded lower accuracy or longer RTs. The ERP results locked to the matrix problems revealed that intrinsic cognitive load enhanced N1, N400 and LPC amplitudes, indicating more attentional resources, rule extraction and conclusion revision processes during high load conditions, respectively. In addition to N1, N400, and LPC, emotional states also modulated the P2 amplitude, indicating feature comparison to incomplete 3×3 matrix. These findings provide psychophysiological evidence that emotion, functioning as extraneous cognitive load, modulates relational inductive reasoning through neural mechanisms similar yet distinct from those governing extraneous cognitive load, advancing our understanding of how cognitive load shapes the emotion-reasoning interactions.