Just over two minutes of violent video was enough to make healthy adults feel pressure as painful sooner, at least on one side of the body. A humorous clip of the same length, shown to a matched group, produced no statistically significant change.
The experiment involved 152 pain-free volunteers at Linnaeus University in Sweden and was published April 1 in the Journal of Pain Research. It adds a twist to earlier work by the same lead researcher, which found a funny video could raise pain thresholds. In this study, at least, a bad mood moved pain sensitivity more clearly than a good one.
Four Groups, Four Muscles and a Pressure Gauge
Helena Gunnarsson of Linnaeus University’s psychology department, with Jalal Safipour and Gunilla Lindqvist of its Department of Health and Caring Sciences, recruited 128 students and 24 staff members between September 2023 and May 2024. Their average age was about 28, and 105 of the 152 participants were women.
Everyone first watched a neutral one-minute video. A researcher then used a handheld algometer, a device that presses on muscle with steadily rising force, to find the point where pressure became painful. Measurements were taken on both upper trapezius muscles, near the base of the neck, and on both shins.
Participants were then assigned, in a preset rotating sequence, to one of four groups of 38. One group watched a violent clip, one watched a humorous clip, one watched an instructional video on painting a house, and one simply sat and waited in silence. Each condition lasted 2 minutes and 20 seconds and was followed by a second round of pressure tests.
Self-ratings confirmed that the violent clip felt unpleasant and the funny clip felt pleasant. Volunteers were not told that other groups saw different videos, and each received a movie ticket for taking part.
The baseline tests showed a pattern of their own. Before any emotional video, the neck muscles were far more sensitive than the shins, with average thresholds of about 395 kilopascals compared with about 684.
Negative Feelings Hit the Left Side Hardest
After the violent clip, pressure pain thresholds dropped. Once the researchers corrected for running multiple comparisons, the drop remained significant at the left trapezius and the left shin, with large effect sizes. Readings on the right side also fell but did not pass that stricter test.
The humorous video produced no significant change at any of the four sites. Sitting quietly did nothing either. The dull house-painting video, however, lowered the threshold at the left shin.
The authors could not fully explain the left-sided pattern. They offered a speculative idea involving how the right side of the brain’s amygdala, an emotion-processing region, handles negative content, while noting that research on this question is inconclusive. They also described it as unexpected that the largest effect appeared at the shin, the less sensitive site.
For the boring video, which participants rated as neutral and low in arousal, the authors suggested that internal processes might have heightened sensitivity. Free mind-wandering in silence, they proposed, may have been even less arousing than watching a dull video.
A Funny Clip That Worked Once but Not Twice
The humor result contrasts with a separate trial by Gunnarsson and psychologist Jens Agerström, published in the Scandinavian Journal of Pain and previously covered by MedicalDaily. In that randomized study of 114 pain-free adults, induced boredom lowered pressure pain thresholds at all four sites, while humor raised them at both trapezius muscles.
The new paper offers one possible reason for the mismatch. The authors suggested participants may not have found their humorous clip funny enough. On the rating scale, the funny video shifted mood less than the violent video did, so the two emotional jolts were not equally strong.
Small Lab Effects, Open Clinical Questions
The authors suggested that if everyday emotional swings shift pain thresholds, lasting negative emotions during acute pain might play a role in recovery. They proposed that clinicians aim for emotionally positive experiences during painful examinations and that patients might watch pleasant content during short, painful procedures.
Those ideas remain untested in patients. The study involved healthy volunteers, measured thresholds minutes after a single video, and did not track real-world pain. The study was registered in advance, but assignment followed a preset sequence rather than true randomization, and the experimenter knew which video each person saw. Pressure points were always tested in the same order, the sample was mostly women, and the team did not control for sleep, caffeine, exercise, or a history of anxiety or depression.
The Linnaeus group has continued the work. It has completed a follow-up trial testing boredom during experimental pain that enrolled 161 participants, though results have not yet been published.
People living with chronic pain who notice that mood affects their symptoms should discuss it with a clinician, since psychological approaches can be used alongside medical care.
Key Questions Answered
What did the Swedish study find?
A violent video lowered pressure pain thresholds at the left neck muscle and left shin, while a humorous video had no significant effect.
How many people took part?
The study included 152 pain-free adults, split evenly into four groups of 38.
What is a pressure pain threshold?
It is the amount of pressure at which a person first feels pain, measured here with a handheld device pressed on the muscle.
Why does this differ from earlier findings?
An earlier trial by the same lead researcher found humor raised thresholds. The new study’s authors suggested their funny clip may not have been funny enough.
Does this apply to people with chronic pain?
Not yet. The study involved healthy volunteers and brief lab measurements, so its relevance to patients remains unknown.
Published by Medicaldaily.com
