The Trier Social Stress Test (TSST) is a standardized, laboratory protocol designed to reliably induce moderate psychosocial stress in human participants. Developed at Trier University in 1993, the test provides researchers with a controlled method to activate the body’s primary stress response systems, particularly the hypothalamic-pituitary-adrenal (HPA) axis. This controlled induction of acute stress allows for the investigation of the connection between the mind and body under duress. The TSST enables scientists to study individual differences in stress reactivity and the biological pathways involved.
The Step-by-Step Procedure
The core of the TSST procedure is a timed, two-part performance task delivered in the presence of an evaluation committee. Before the test begins, participants are informed they must prepare a five-minute speech, often framed as a job interview, where they must convince the committee they are the ideal candidate for a position. This preparation phase typically lasts about ten minutes, generating anticipatory stress as the participant faces the looming performance.
The stressor is intensified by the presence of two or three non-responsive judges, who are trained to maintain stern, neutral expressions and take notes throughout the performance without offering encouragement or feedback. The participant then delivers the five-minute speech while standing in front of the committee, often being videotaped and audio-recorded for “later analysis,” which further amplifies the feeling of social evaluative threat.
Immediately following the speech, the participant is subjected to a second five-minute task: a surprise mental arithmetic test. This task requires the participant to serially subtract a challenging number, such as 13, from a large four-digit number like 1,022, out loud and at a fast pace. The element of uncontrollability is built in by requiring the participant to immediately restart the entire sequence from the beginning if any error is made during the subtraction. This combination of social evaluation and performance failure under strict time constraints reliably triggers the stress response.
How Researchers Measure the Stress Response
The standardized TSST procedure is paired with the collection of both physiological and psychological data to quantify the stress response. One of the most frequently collected physiological markers is the stress hormone cortisol, which is measured from saliva samples taken at timed intervals before, during, and up to an hour or more after the test. Salivary cortisol levels generally peak around 10 to 20 minutes after the stressor concludes, reflecting the delayed activation of the HPA axis.
Researchers also monitor markers of the sympathetic nervous system, the body’s immediate “fight or flight” response. This includes measuring heart rate and heart rate variability, as well as blood pressure, which offer real-time data on autonomic activation during the stressor. Some studies also measure other neuroendocrine markers, such as alpha-amylase in saliva, which reflects the activity of the sympathetic-adrenal-medullary (SAM) axis.
To assess the psychological impact, participants complete subjective measures at various points throughout the protocol. These often involve questionnaires or visual analog scales to rate their levels of perceived stress, anxiety, and mood. By comparing these self-reported feelings to the concurrent biological data, researchers gain a comprehensive picture of how the induced stress is experienced and manifested internally.
Why the TSST is the Gold Standard for Stress Research
The TSST has earned its position as the gold standard in experimental stress research due to its methodological rigor and proven efficacy. It is standardized, meaning the exact sequence, timing, and environmental conditions are controlled and replicable across different laboratories worldwide. This standardization allows scientists to directly compare findings from studies conducted in various countries and with diverse populations.
The test reliably activates the main biological stress systems, consistently eliciting a two-to-threefold increase in salivary cortisol levels in approximately 70 to 80 percent of healthy participants. This predictable neuroendocrine response is an advantage over older stress paradigms, which often produced inconsistent or weak physiological effects. The reliability of the TSST ensures that any observed differences are likely due to the experimental variable being tested, rather than a failure of the stress induction itself.
What the TSST Has Taught Us About Human Stress
Decades of research utilizing the TSST have provided insights into the factors that modulate the human stress response. Studies have consistently demonstrated sex differences, with men typically exhibiting a stronger cortisol response than women, though the female response is dependent on the phase of the menstrual cycle or the use of oral contraceptives. This suggests that gonadal hormones play a role in regulating HPA axis reactivity to psychosocial challenge.
The test has also illuminated the impact of social variables, revealing that the presence of social support can suppress the cortisol response to the stressor. Conversely, individuals dealing with chronic stressors have sometimes shown a blunted or hypo-reactive cortisol response, suggesting a wear-and-tear effect on the stress system. Research has also shown that while acute stress from the TSST can enhance the consolidation of new memories, the same stress impairs the retrieval of memories formed prior to the test.