A pilot study on changes of cardiac vagal tone in individuals with low trait positive affect: The effect of positive psychotherapy

• Individuals with high trait PA had higher basal RSA.
• Positive Psychotherapy increased trait PA and basal RSA, and decreased trait NA.
• Increases in trait PA were related to increases in basal RSA.

The association between changes of trait affect and changes of vagal tone was investigated in the present study. Basal physiological data were collected from 70 college students of high (n = 33) and low trait positive affect (n = 37) (HPA vs. LPA) groups selected by Positive and Negative Affect Schedule (PANAS). Then the final LPA participants (n = 34) were randomly assigned to either a four month Positive Psychotherapy (PPT) group (n = 16) or a control group (n = 18), and their basal physiological and PANAS data were collected immediately after the treatment. The study results showed that compared to the LPA group, the HPA group had higher basal respiratory sinus arrhythmia (RSA). Compared to the control group, the PPT group had changes in trait affect and basal RSA, and increases in trait PA were associated with increases in basal RSA independently of decreases in trait NA. These findings suggest that basal vagal tone of individuals with low trait PA might be improved by increasing their trait PA.