Summary: A new study demonstrates that transcranial direct current stimulation (tDCS), a non-invasive brain stimulation technique, can influence the speed and flexibility of decision-making. Researchers applied stimulation to the dorsolateral prefrontal cortex (dlPFC)—a region central to planning and action selection—while participants performed simultaneous visual and auditory tasks and chose the order in which to complete them.
The experiment found that anodal tDCS, which tends to enhance neuronal excitability, produced faster task-order decisions. In contrast, cathodal tDCS, which tends to inhibit neural activity, increased the likelihood that participants repeated a previously chosen task order. Although the effects were modest—on the order of roughly 100 milliseconds—they were statistically meaningful within the context of cognitive neuroscience and experimental psychology.
Key Facts:
- Targeted brain area: Stimulation targeted the dorsolateral prefrontal cortex, a region implicated in planning, action selection, and task coordination.
- Effect on flexibility: Anodal stimulation accelerated voluntary changes in task order; cathodal stimulation reduced the tendency to switch, promoting repetition of prior choices.
- Cognitive impact: Measured differences were small (~100 ms) but statistically significant and consistent with altered cognitive control and decision dynamics.
Source: Martin Luther University Halle-Wittenberg
Overview
Researchers at Martin Luther University Halle-Wittenberg (MLU) published these findings in the Journal of Cognitive Neuroscience. The study used transcranial direct current stimulation (tDCS), a widely used, non-invasive approach in both research and clinical contexts. In tDCS, a very weak electric current flows between electrodes placed on the scalp to modulate cortical excitability: anodal stimulation generally increases neuronal activity, while cathodal stimulation typically suppresses it.
MLU psychologist Dr. Sebastian Kübler highlights the practical advantages of tDCS: it is non-invasive, easy to apply, and therefore common in psychological experiments. Its therapeutic potential for neurological and psychiatric conditions is actively researched, but robust clinical claims remain under study.
The experimental group consisted of 40 participants. Electrodes were positioned to stimulate the dorsolateral prefrontal cortex—an area known for its role in planning, weighing options, and coordinating multiple actions. During each session, participants simultaneously received a visual and an auditory task and were free to decide which task to perform first. Electrodes were worn throughout, and the study used a blinded design: neither participants nor experimenters knew whether anodal, cathodal, or sham stimulation was applied in a given session. Sessions were spaced by at least one week to avoid carry-over effects.
Results showed that anodal stimulation facilitated voluntary switching of task order: reaction times were shorter when participants intentionally changed the order compared with sham stimulation. By contrast, cathodal stimulation reduced the tendency to switch, leading participants to repeat their previous order more often. These findings support a causal role of the dlPFC in voluntary task-order coordination during multitasking situations.
Although a difference of about 100 milliseconds may seem small, such shifts are meaningful in experimental paradigms that measure cognitive control and decision dynamics. The authors interpret these changes as evidence that modulating dlPFC excitability alters the updating and implementation of task-order information needed to schedule overlapping tasks.
The market now offers consumer tDCS devices that claim to boost creativity or concentration. The study authors caution that broad commercial claims are not supported by current evidence. Their results do indicate that tDCS can influence cognitive processes like decision-making under controlled experimental conditions, but effects are subtle and depend on stimulation parameters, task demands, and individual differences.
About this brain stimulation and decision-making research news
Author: Tom Leonhardt
Source: Martin-Luther-Universität Halle-Wittenberg
Contact: Tom Leonhardt – Martin-Luther-Universität Halle-Wittenberg
Image: The image is credited to Neuroscience News
Original Research: Closed access. “Transcranial Direct Current Stimulation of the Dorsolateral Prefrontal Cortex Modulates Voluntary Task-order Coordination in Dual-task Situations” by Sebastian Kübler et al. Journal of Cognitive Neuroscience
Abstract
Transcranial Direct Current Stimulation of the Dorsolateral Prefrontal Cortex Modulates Voluntary Task-order Coordination in Dual-task Situations
Dual tasks require additional control processes to coordinate the timing of two component tasks. Prior imaging and noninvasive stimulation work implicates the dorsolateral prefrontal cortex (dlPFC) in task-order coordination, but most such studies used externally imposed order rules. It remained unclear whether the dlPFC also supports voluntary, internally generated order choices.
To investigate this, the authors conducted two experiments applying anodal (Experiment 1) and cathodal (Experiment 2) tDCS during a random-order dual-task paradigm that allowed participants to freely choose the processing order. Anodal and cathodal stimulation produced facilitatory and inhibitory effects, respectively, on voluntary task-order coordination. Specifically, anodal stimulation shortened reaction times when participants switched task order relative to the preceding trial, while cathodal stimulation reduced the likelihood of switching compared with sham stimulation. These results indicate a causal role of the dlPFC in intentionally updating and implementing task-order information necessary for scheduling overlapping tasks.