Brain Stimulation and Mental Workload Steer How We Explore, Gamble, and Seek Information

Every day, people make decisions without ever knowing the true odds. Choosing a new route to work, testing an unfamiliar restaurant, or investing savings in an uncertain market all share a common structure: we must sometimes stick with what we know, sometimes gamble on something better, and sometimes pay a price just to learn more about our options. A new study published in PLOS One by Ankit Singh, Varun Dutt, and Akash K. Rao examines how two hidden forces—how busy our working memory is, and how active a specific patch of the prefrontal cortex is—shape this delicate balancing act. The results reveal that exploration, risk-taking, and information seeking are not one unified behavior but separable processes that respond differently to mental strain and to direct brain stimulation.

The research team recruited 60 healthy adults and asked them to complete a computerized decision-making task consisting of 50 trials. On each trial, participants faced three options. One was a safe choice, offering a modest but reliable payoff. The second was a probabilistic high-reward choice, which could deliver a large payoff but only with uncertain probability that participants had to learn from experience. The third was a costly information-seeking option: paying a small price to glimpse how the risky option was likely to behave. This design captures the classic explore–exploit dilemma in a laboratory setting, because learning about the risky option requires sampling it, yet sampling carries the danger of losses. Crucially, participants never received full descriptions of the probabilities; they had to infer them from the outcomes of their own choices, which is exactly how most real-world decisions work.

To manipulate cognitive load, the researchers used a trivia-based procedure. In the load condition, participants answered trivia questions of varying difficulty, while a control group completed the task without any trivia demands. Within the load subgroup, the trial-level analysis distinguished lower-load and higher-load trivia questions, allowing the team to examine whether harder mental work produced different decision patterns than easier mental work. The second manipulation was physiological: half of the participants received anodal transcranial direct current stimulation, or tDCS, over the left dorsolateral prefrontal cortex, a region long implicated in executive control, working memory, and the regulation of exploratory behavior. The other half received sham stimulation, which mimics the sensations of tDCS without delivering meaningful current. This produced a 2 × 2 between-subjects design crossing stimulation with cognitive-load condition.

tDCS is a non-invasive technique that passes a weak electrical current through the scalp, subtly shifting the excitability of neurons in the targeted cortical region. Anodal stimulation is generally thought to increase cortical excitability, making the underlying neurons more responsive. The left dorsolateral prefrontal cortex is a frequent target in such studies because it supports cognitive control processes that govern when we persist with familiar strategies and when we switch to alternatives. By combining this neuromodulatory approach with a behavioral load manipulation, the researchers could ask whether the effects of brain stimulation depend on how hard the brain is already working—a question that additive models of cognition would answer with a simple yes or no, but that the data answered in a more nuanced way.

The primary findings split cleanly along outcome lines. Cognitive load slowed participants down and made them less willing to take risks. When working memory was occupied by trivia, people responded more slowly and gravitated toward the safe option, consistent with the idea that mental strain pushes decision-makers toward conservative, low-effort strategies. Anodal tDCS over the left DLPFC produced the opposite pattern on the choice side: stimulated participants made more risky choices, sought more information, and alternated more frequently between the different choice types. Notably, stimulation did not significantly change reaction times, suggesting that the current influenced what people chose rather than how quickly they decided. This dissociation between choice content and response speed is important, because it implies that prefrontal neuromodulation alters the underlying decision policy rather than simply speeding up or slowing down general processing.

The most intriguing results emerged from the interaction analyses. Stimulation and cognitive load interacted significantly for two of the outcome measures: information seeking and alternation between choice types. In other words, the effect of anodal tDCS on these behaviors depended on whether participants were under trivia load, and the pattern of load effects differed between the stimulated and sham groups. For reaction time and risky choice, by contrast, the interactions were not significant, meaning the effects of load and stimulation on those measures were essentially additive. This outcome-specific pattern suggests that different components of experience-based decision making recruit the prefrontal cortex to different degrees and respond to neuromodulation under different cognitive circumstances. Information seeking—a behavior that reflects curiosity and the willingness to pay for knowledge—appears especially sensitive to the joint state of cortical excitability and mental workload.

The secondary, trial-level analysis added further texture. When the researchers compared trials immediately following higher-load trivia questions with those following lower-load questions, they found that participants took longer to decide after the harder questions. However, this trial-level load difference did not extend to the choice outcomes themselves: harder trivia did not reliably change risky choice, information seeking, or alternation on a trial-by-trial basis. This suggests that the burden of a single difficult question manifests mainly as slower deliberation, while the broader load condition shapes strategy at a more global level. The distinction between moment-to-moment cognitive strain and sustained cognitive demand may therefore be critical for understanding how mental workload influences decisions in everyday settings, from a surgeon working through a long operation to a trader processing a stream of market data.

Why should these findings matter beyond the laboratory? The explore–exploit tradeoff is one of the most fundamental problems in behavioral science, economics, and machine learning, and this study shows that its components can be pulled apart experimentally. Risk-taking, information seeking, and behavioral flexibility each responded to load and stimulation in their own way, which cautions against treating exploration as a single psychological quantity. The results also carry practical implications for the growing field of cognitive enhancement. If anodal DLPFC stimulation boosts risk-taking and information seeking in one context but interacts with mental workload in another, then claims about stimulation as a universal performance booster need refinement. The same current that encourages healthy exploration in a rested mind might behave differently when attention and memory are already taxed.

The study also speaks to clinical questions. Altered exploration and risk sensitivity are hallmarks of several psychiatric and neurological conditions, including addiction, attention-deficit disorders, and damage to the frontal lobes. Understanding how prefrontal neuromodulation shifts these behaviors in healthy adults provides a baseline for future work asking whether tDCS could help restore adaptive decision-making in clinical populations, or whether cognitive load might be used diagnostically to probe the integrity of prefrontal control systems. Because the current study involved 60 healthy adults and a single session, the authors’ conclusions are appropriately modest: they demonstrate outcome-specific joint effects of load and stimulation, including both additive and context-dependent patterns, rather than establishing long-term or therapeutic effects.

What emerges from Singh, Dutt, and Rao’s work is a picture of the deciding brain as a system whose exploratory urges, appetite for risk, and hunger for information are governed by partly independent levers. Fill the mind with trivia, and people retreat to safety and slow down. Excite the left dorsolateral prefrontal cortex with a gentle current, and they reach for the risky option, pay for information, and shuffle more freely among strategies. But the two levers do not simply add together; for some behaviors, the state of one changes how the other operates. As non-invasive brain stimulation moves closer to everyday use, studies like this one serve as a reminder that the brain’s decision circuits cannot be understood—or tuned—one factor at a time.

Subject of Research: Effects of cognitive load and prefrontal tDCS on exploration, risk-taking, and information seeking in experience-based decision making

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

Article References: Singh, A., Dutt, V., & Rao, A. K. (2026). Cognitive load and prefrontal neuromodulation shape exploration, risk-taking, and information seeking in experience-based decision making. PLOS One, 21(10), e0360059. https://doi.org/10.1371/journal.pone.0360059

Image Credits: AI Generated

DOI: 10.1371/journal.pone.0360059

Keywords: cognitive load, tDCS, dorsolateral prefrontal cortex, decision making, exploration, risk-taking, information seeking, neuromodulation, working memory, PLOS One, Cognitive, load