Posted 02.23.2018 | by AMRA

Event-related potentials (ERPs) are segments of brain waves occurring in response to stimuli. For example, when people with depression are shown happy faces, the amplitude of their ERPs 300 milliseconds later (the so-called “P3b” ERP) is smaller than in non-depressed people. Since mindfulness encourages openness to emotions, mindfulness may enhance P3b responding to emotional stimuli and perhaps play a role in reducing or preventing depressive symptoms.

In a pioneering study of adolescent brain function and school mindfulness programs, Sanger el al. [Developmental Science] tested whether a high school mindfulness-training program could affect the size of healthy students’ P3b responses to happy and sad faces, and whether it improved their wellbeing relative to a control group.

The researchers assigned 40 students (16-18 years old) to mindfulness training or a waitlist control. Assignment was not random. Volunteers from two secondary schools were assigned to mindfulness training, and volunteers from two other secondary schools were assigned to the waitlist control. Control volunteers were slightly older and more likely to be male.

Participants completed the Five Facet Mindfulness Questionnaire (FFMQ) along with measures of stress, wellbeing, and empathy, both before and after training. Schoolteachers taught the mindfulness practices in eight 50-minute classes. Curriculum topics included “Taming the Animal Mind, “Being Here and Now,” “Moving Mindfully,” and “Befriending the Difficult.”

Before and after training, students were shown pictures of faces with varying expressions while an EEG measured their P3bs. Most of the faces shown were neutral, but 20% were happy or sad. Participants were instructed to press a space bar whenever they saw a happy or sad face.

Mindfulness levels did not increase over time, nor did they differ between the mindfulness trainees and controls. Wellbeing improved significantly for the mindfulness group and decreased marginally for waitlist controls, a difference between groups that was marginally significant (η2=.06). The mindfulness group was less empathic than the controls both before and after training. Within the mindfulness group, empathy correlated significantly with class attendance (r=.66) and marginally with home practice (r=.49).

Control group ERP magnitudes decreased from pre- to post-testing, but the mindfulness group’s ERP magnitudes stayed the same (η2=.12). The magnitude of ERP change scores in response to happy and sad faces correlated positively with pre-to-post changes in empathy scores (happy faces r=.37; sad faces r=.33). The results demonstrate that adolescents in a school-based mindfulness program show less habituation in their P3b responses to emotional cues.

Mindfulness training seems to prevent a diminished response to happy and sad faces over time. It’s often said that mindfulness helps one to “keep things fresh” and not assume there’s no new information in repeated stimuli, and this may be an example of that. Changes in P3b magnitudes varied with changes in empathy, suggesting that decreased habituation may be due to an increased attentiveness to socially relevant emotional cues. The study is limited by its lack of randomization and an active control group.


Sanger, K. L., Thierry, G., & Dorjee, D. (2018). Effects of school-based mindfulness training on emotion processing and well-being in adolescents: Evidence from event-related potentials. Developmental Science.

[Link to abstract]