Indecision is a common human experience, whether people are choosing what to watch on television or making important life decisions. While gathering more information can improve accuracy, excessive information seeking can become costly and even debilitating. A recent article published in Nature Human Behaviour sheds light on why some individuals struggle to make decisions, identifying a specific bias in how the brain integrates information over time.
The study focuses on obsessive-compulsive (OC) symptoms, which are frequently associated with persistent doubt and indecisiveness. The authors combined large-scale behavioural data with laboratory testing and brain imaging to identify a key motivational cognitive process underlying this indecisiveness: reduced sensitivity to new information. The investigation began with a crowd-sourced sample of 5,237 participants who completed an information-gathering task via a mobile application. Participants were asked to determine which of two options was more abundant across 25 hidden locations and could sample as many locations as they wished before committing to a choice—the number of samples taken served as a behavioural measure of indecisiveness.
Computational modelling revealed that the strength of the evidence updates (ΔES), which is defined as the difference between the cumulative evidence across consecutive samples, had a substantial effect on decision-making. Decisions were driven more strongly by the recent evidence compared to older information, demonstrating a robust recency effect. The likelihood of making was predicted by both overall evidence strength and ΔES (β = 1.105, P <0.001, 95% confidence interval [CI]: 1.086–1.123 and β = 1.042, P < 0.001, 95% CI: 1.029–1.055), with ΔES exerting the stronger effect.
Notably, individuals with higher OC symptoms gathered more information before making a decision (β = 0.040, P = 0.004), but no difference in the accuracy of the decision was found (0.998 × 10⁻4, P = 0.942). This indecisiveness was attributable to reduced motivation or altered urgency. Rather, stronger OC symptom severity was correlated with no longer weighing of recent evidence, especially ΔES (β = −0.085, P < 0.001, 95% CI: −0.104 to −0.067).
These findings were replicated in a second, lab-based study, involving a smaller sample (N = 105) that incorporated patients with obsessive-compulsive disorder (OCD) as well as those with generalized anxiety disorder and non-clinical participants. Again, ΔES significantly predicted decision-making (β = 0.830, P < 0.001, 95% CI: 0.791–0.869), and higher OC symptoms were linked to reduced reliance on ΔES (β = −0.049, P = 0.013). Among OCD patients, reduced ΔES weighting was specifically correlated with the severity of obsession, but not with compulsive symptoms.
The researchers also analyzed the brain activity through magnetoencephalography (MEG). They discovered neuronal signals corresponding to ΔES that peaked around 920 ms after the stimulus onset. Importantly, the participants with higher OC symptoms exhibited attenuated ΔES-related activity in the medial frontal brain areas, although other decision-related neural processes remained intact.
Taken together, these results suggest that indecisiveness along the obsessive–compulsive spectrum does not arise from excessive caution or reduced motivation, but rather from a reduced influence of the most recent information during the decision-making process. By identifying this mechanism, the study offers a clearer neurocognitive account of pathological indecision and highlights potential targets for interventions aimed at improving decision confidence in individuals with OCD and related disorders.
References: del Río M, Trudel N, Prabhu G, et al. Indecision and recency-weighted evidence integration in non-clinical and clinical settings. Nat Hum Behav. 2026. doi:10.1038/s41562-025-02385-1
