Everyday choices ask us to balance a safe option against a tempting gamble—and sometimes to pay for more information. This study finds that mental busyness and mild brain stimulation can shift those choices in different ways. Human decision making in uncertain environments requires a continuous balance between exploring new alternatives and exploiting familiar options that have yielded favorable outcomes in the past.

In ordinary life, it is like choosing whether to keep ordering the meal you already know you like or try something unfamiliar that might be better. Previous studies have generally examined cognitive load and prefrontal stimulation separately.

Consequently, it remains unclear whether concurrent cognitive demand and stimulation produce broadly additive effects or whether the effect of stimulation changes when decision making is performed under additional cognitive demand. The study addressed this question with repeated choices between safe, risky, and information-seeking alternatives.

The experiment compared stimulation with sham stimulation, and trivia-based mental demand with no-trivia control. Within the trivia condition, lower-load and higher-load trivia were presented across trials. The study examined response time, risky choice, information seeking, and switching between choice types as distinct signs of decision behavior under uncertainty.

In the no-trivia control condition, the trial began directly with the decision screen. The figure illustrates the task sequence, including the decision screen and outcome feedback, while the control condition began directly with that decision screen.

The sequence makes the added mental burden visible: a knowledge question and correction come before the choice, followed by the decision and its consequence, while the participant performs it at a computer. Cognitive load affected response time and risky choice, while stimulation affected risky choice, information seeking, and switching between choice types.

The combination was not the same across outcomes: the interaction between stimulation and cognitive load appeared for information seeking and switching, but not for response time or risky choice. The findings therefore did not support one uniform additive pattern across all outcomes.

Information seeking was higher overall under stimulation than under sham stimulation. The overall effect of cognitive-load condition was not significant, but the interaction between stimulation and cognitive load was significant.

The means showed a crossover pattern: under sham stimulation, information seeking was lower with trivia-based load than with no-trivia control. Trial-level cognitive load primarily influenced response time, while risky choice, information seeking, and switching were largely unaffected.

There was no evidence that trial-level cognitive load systematically modified the behavioral effects of stimulation. Concurrent trivia slowed responses and reduced risky choice, while stimulation was associated with greater risky choice, information seeking, and exploratory switching.

The joint pattern was not uniform: response time and risky choice showed no significant interaction, whereas information seeking and switching showed significant crossover interactions. For someone making decisions under uncertainty, this means mental demand and stimulation may change different parts of behavior rather than simply making every choice more cautious or more daring.

A crowded mind does not change every decision in the same way. Cognitive demand slowed choices and reduced risk, while stimulation increased risk, information seeking, and switching—but the combination depended on the kind of choice.