The Stroop Competition: A Social-Evaluative Stroop Test for Acute Stress Induction

The Stroop test is one of the most widely used protocols to induce cognitive stress and reliably activates the sympathetic nervous system (SNS). However, it only moderately activates the hypothalamic-pituitary-adrenal (HPA) axis, the stress axis responsible for cortisol secretion. In other well-known stress protocols, such as the cold pressor test, adding social-evaluative elements to the regular procedure has proven to cause increased HPA axis activation. For this reason, we introduce the “Stroop Competition”, a novel stress protocol based on the established Stroop test that adds social-evaluative feedback by conducting the test against a fake opponent with subsequent performance evaluation. We investigated the stress response of 22 participants performing either the “Stroop Competition” (Competition group) or the regular Stroop test (Control group) three consecutive times. Stress responses were assessed using ECG recordings to extract heart rate (HR) and heart rate variability (HRV) and saliva samples to extract salivary alpha-amylase (sAA) and cortisol. In the Competition group, participants experienced higher SNS activation indicated by significantly higher HR and lower HRV levels as well as higher sAA response to the stressor compared to the Control group. Additionally, overall cortisol levels were significantly higher in the Competition group supporting higher HPA axis activity. The findings of our pilot study confirm our hypothesis that adding social-evaluative elements to the Stroop test causes a more effective activation of both the SNS and HPA axis. We are convinced that our novel “Stroop Competition” protocol will provide a valuable addition to the already existing stress protocols in biopsychological research.