Stress Levels Escalate When Repeatedly Performing Tasks Involving Threats

Bertilsson, Johan; Bertilsson, Johan; Niehorster, Diederick C.; Niehorster, Diederick C.; Niehorster, Diederick C.; Fredriksson, Peter Jan; Dahl, Mats; Granér, Simon; Fredriksson, Ola; Mårtensson, Johan Magnus; Magnusson, Måns; Fransson, Per-Anders; Nyström, Marcus · 2019 · DOAJ

DOI: 10.3389/fpsyg.2019.01562

archive: archived pipeline: cataloged verified

Get this paper ↗ (DOI — opens at the source; we link to it, we don't host it)

Summary

This study investigates how repeatedly performing stressful tasks affects physiological stress markers in police officers, addressing a gap in understanding the cumulative physical impact of sequential threat exposure. Police work often involves repeated stressful events that can impair perceptual, cognitive, and motor performance, yet it remains unclear how such repetition physically affects officers in terms of heart rate and pupil diameter. The research aimed to determine if repeated moderately stressful tasks cause an altered stress response and whether heart rate and pupil diameter reflect these changes similarly. The experiment involved 12 healthy male police officers with at least five years of field experience. Participants performed a sequence of four stressful scenarios involving immediate or delayed threats (e.g., hostage situations with knives or guns), each lasting between 20 and 130 seconds. Between tasks, officers rested for approximately 30 seconds in a dimly lit anteroom before entering a brightly lit scenario room. Heart rate was monitored using a Zephyr Bioharness, and pupil diameter was recorded via eye-tracking glasses. Physical activity was controlled and monitored, ensuring walking cadence remained low. Statistical analysis included repeated measures GLM ANOVA and regression models to assess changes in biomarkers across task phases (pre-onset, post-onset, pre-offset, post-offset). Results indicated that repeatedly performing stressful tasks caused a significant escalation in heart rate ($p = 0.005$). Heart rate increased significantly before entering the scenario room and was higher immediately after task onset compared to before onset ($p < 0.001$), with this pattern being most pronounced during the first tasks. The issuance of a verbal "abort" command also triggered a significant heart rate increase ($p = 0.002$), particularly in early tasks. Pupil diameter exhibited a complex pattern, reaching a minimum during the second task followed by an increase during tasks three and four ($p \leq 0.020$). While heart rate showed a linear increase over time, pupil diameter followed an exponential regression model. Notably, heart rate at rest correlated significantly with heart rate during the first task's pre-onset phase. The findings suggest that repeated exposure to stressful tasks produces an escalation of psychological stress, even prior to the actual execution of the task. The distinct patterns observed in heart rate and pupil diameter indicate that these biomarkers reflect different characteristics of the stress response. The study concludes that monitoring heart rate is a useful tool for screening stress responses and determining when personnel rotation is necessary to avoid sustained high-stress exposure. These results highlight the importance of understanding the dynamics of stress-generating factors to optimize police training and operational safety.

Provenance

The full processing record for this entry. Every stage of this paper's journey through the pipeline is logged — what ran, with which tool and model, how many attempts it took, and when it last completed.

Summary generated by qwen3.6-27b-prismaquant on 2026-06-26; verification: verified.

Topics

Ranked by relevance to this paper. Hover a topic for its definition.

• workload measurement

Information type

What kind of knowledge this paper contributes, grouped by family — independent of topic (what it is about) and method (how it was studied).

• Empirical Findings: physiological data