Stimulation of left dorsolateral prefrontal cortex enhances willingness for task completion by amplifying task outcome value.

Procrastination, an irrational delay of intended action, has caused harms in many life domains. Although procrastination has a robust link with the dorsolateral prefrontal cortex (DLPFC), the causal role of DLPFC in this behavior remains unclear. A recent temporal decision model (TDM) proposed that people pit task aversiveness against outcome value to decide to procrastinate or not. In short, people would procrastinate if task aversiveness has a stronger effect than outcome value. According to the TDM, the DLPFC might reduce procrastination by inhibiting task aversiveness, or amplifying outcome value, or both. The present study tested those possibilities by investigating whether brain stimulation on DLPFC changes procrastination and its underlying mechanism. One hundred and three participants with high procrastination were randomly assigned to receive either active or sham stimulation over the left (active, n = 27; sham, n = 27) or right (active, n = 25; sham, n = 24) DLPFC and rated task aversiveness, outcome value and task-execution willingness toward their self-planned real-life tasks before and after stimulation. We found that active stimulation of the left DLPFC significantly boosted task-execution willingness. This left DLPFC stimulation also changed subjects' evaluation of tasks such that decreasing task aversiveness and increasing outcome value. Causal mediation analyses further revealed that stimulation of the left DLPFC enhances willingness for task completion through increasing outcome value. Overall these results provide the first evidence that neuromodulation of the left DLPFC could improve timely task-execution willingness via increasing the outcome value, which offers new insights for treating individuals with severe or even pathological procrastination. (PsycInfo Database Record (c) 2023 APA, all rights reserved).