Cognitive load and prefrontal neuromodulation shape exploration, risk-taking, and information seeking in experience-based decision making

Abstract

Experience-based decision making requires individuals to balance exploration and exploitation under uncertainty, a balance that may be influenced by cognitive demands and prefrontal neuromodulation. We examined the joint effects of trivia-based cognitive load and anodal transcranial direct current stimulation (tDCS) over the left dorsolateral prefrontal cortex (DLPFC) in 60 healthy adults. The primary 2 × 2 between-subjects design crossed Stimulation (anodal tDCS vs sham) with Cognitive-Load Condition (Trivia-Based Load vs No-Trivia Control). Within the Trivia-Based Load subgroup, Lower-Load and Higher-Load Trivia were presented across trials for a secondary trial-level analysis. Participants completed 50 decisions involving a safe choice, a probabilistic high-reward choice, and a costly information-seeking choice. Primary analyses showed that Trivia-Based Load slowed responses and reduced risky choice. Anodal tDCS increased risky choice, information seeking, and alternation between choice types, but did not significantly affect reaction time. Stimulation × Cognitive-Load Condition interactions were significant for information seeking and alternation, reflecting different load-related patterns under anodal tDCS and sham, whereas interactions were not significant for reaction time or risky choice. Secondary analyses indicated longer decision times following Higher-Load than Lower-Load Trivia, without corresponding trial-level load effects on the choice outcomes. These findings show that cognitive load and anodal DLPFC tDCS have outcome-specific joint effects on experience-based decision making, including both additive and context-dependent patterns.