How Confident Are People in Their Actions?

By Maryna Mullerman ‘20


Figure 1. In the experiment discussed, OCD patients showed a dissociation between their confidence and actions.

Confidence is thought to be based on previous experiences and outcomes, while new information modifies human perception of the environment. Matilde M. Vaghi and researchers from the University of Cambridge conducted a study to find a dissociation between action and confidence. They focused on obsessive-compulsive disorder (OCD) patients who struggled with repetitive behavior. Their findings revealed a novel aspect of human decision-making mechanisms.

The study included 25 healthy individuals for a control group, as well as 24 OCD patients matched for gender, age, and verbal IQ.  Sixteen experimental group participants were continuously taking serotonin reuptake inhibits (SSRIs); thus, the patients were divided into four groups based on their medication dosages. Participants were asked to catch a particle released from a center of a circle — with a bucket that could be placed at the circle’s edge. After positioning the bucket, the participants rated the confidence of their choices on a scale from 1 to 100. After multiple trials, the directionality of particle landing changed. The effects of the environmental change on decision making and confidence levels were reflected in belief estimate charts. The learning rate (LR) was computed for each participant, and the results were compared to the Bayesian learning model, a standard for finding the best action using probability.

Although large errors produced higher LRs, the OCD patients were more influenced by recent outcomes than healthy patients. There were no significant differences among the groups’ confidence level changes. The OCD patients utilized the knowledge to adjust their confidence levels, but they were unable to use it to control their actions. The experimental group’s participants changed the position of the bucket based on recent outcomes rather than the average of all past trials, so they were unable to perceive the broader context.

The researchers implied a correlation between the degree of dissociation between confidence and action and OCD symptom severity. They suggested that uncoupling in this mechanism might be a basic element in this disorder, with “beliefs” independently directing actions. The researchers were only limited to direct comparisons between OCD patients, but the study presents a novel advancement towards understanding OCD.



  1. M. Vaghi, et. al., Compulsivity reveals a novel dissociation between action and confidence. ScienceDirect 96, 348-354 (2017). doi: 10.1016/j.neuron.2017.09.006.
  2. A. Sanborn and N. Chater, Bayesian brains without probabilities. Trends in Cognitive Sciences 20, 883-893 (2016). doi:  10.1016/j.tics.2016.10.003.
  3. Image retrieved from:

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