Physically compressing peoples’ torsos reduces the riskiness of their decisions, study finds

A study examining the effects of torso compression (achieved by wearing shapewear) indicated that it reduces risky decisions (in an experimental game). At the same time, participants exposed to torso compression became more sensitive to sensations coming from the stomach and more aware of signals coming from the heart. The paper was published in Biological Psychology.

Good decisions depend not only on what is happening around us but also on how accurately we perceive what is happening inside our bodies. The ability to detect and interpret internal signals such as heartbeats, hunger, fullness, nausea, and fatigue is known as interoception. These bodily signals can influence emotions, behavior, and decision-making by warning us about risk, stress, or changing physical needs.

People who perceive their internal states more accurately may be less impulsive and more likely to make advantageous choices, although most evidence so far comes from studies that do not allow causal inferences. Researchers are therefore increasingly interested in whether deliberately changing bodily sensations can directly alter decisions. One possible method is body compression, because pressure from tight garments may intensify signals from the stomach or heart and draw greater attention to the body.

Stefania Polzin, a researcher affiliated with the German Institute of Human Nutrition and other institutions, and colleagues investigated the effects of torso compression on people’s cardiac interoceptive accuracy, cardiac interoceptive awareness, and gastric interoceptive sensitivity.

In other words, they investigated whether wearing garments that compress the torso—shapewear in this case—will affect accuracy in interpreting signals coming from participants’ hearts, awareness of those signals, as well as their sensitivity to signals coming from their stomach.

They also wanted to see whether this will affect their risk-taking behaviors. Study authors hypothesized that wearing shapewear will increase the perception of signals coming from the heart and stomach and decrease risk-taking. Their expectation was also that this experimentally induced improvement in sensitivity to signals from the stomach and the heart will be associated with lower risk-taking.

Study participants were 44 individuals between 18 and 45 years of age. They were required to be physically and mentally healthy, to have a normal weight, no regular intake of medication, and no prior diagnosis of mental or physical illness. They were also required to be fluent in the German language. Participants’ average age was 26 years, and 28 of them were women.

Participants were invited to the researchers’ lab in the morning (10:00 a.m.) on two consecutive days and were asked to abstain from food and water from 9:00 p.m. on the day before the visit. In the lab, they were asked to wear the clothing provided, which was a shapewear garment (in the torso compression condition) on one day, and a loose garment on the other. Shapewear is tight-fitting clothing designed to compress and smooth parts of the body, creating a slimmer or more defined appearance under other clothes.

While wearing the clothing, participants completed tasks measuring risk-decisions and interoception (cardiac interoceptive accuracy, cardiac interoceptive awareness, and gastric interoceptive sensitivity). Cardiac interoceptive accuracy is the ability to perceive the activity of the heart, specifically heartbeats. Participants completed the Heartbeat Discrimination Task. In this task, participants listened to auditory signals and reported whether the signals were in synchrony with their heartbeats.

Cardiac interoceptive awareness was assessed as the level of agreement between the actual accuracy of participants’ answers in the previous task and their self-reported confidence in the given responses being correct.

Gastric interoceptive sensitivity was defined here as the ability to perceive signals of satiety and fullness from the stomach. To assess this, participants completed the Water Load Test. In this test, participants were first asked to drink water until satiation, and then to drink until their stomachs were completely filled with water. Study authors divided the quantity a participant drank to reach satiety by the quantity of water the participant drank to reach fullness and called it satiety percentage. A smaller satiety percentage was interpreted as better gastric interoceptive ability.

Risk-taking was measured using the Columbia Card Task. In this task, there are 32 cards. Most of them earn participants points, but a small number of them are loss cards. Participants choose how many cards they would like to turn over in each trial. Trials differ in the number of loss cards, and the number of points gained per win card or lost per loss card. The number of cards chosen in each trial was an individual’s absolute risk score.

Results showed that participants were less prone to take risks while they were wearing shapewear. Also, their gastric interoceptive sensitivity and cardiac interoceptive awareness increased. Cardiac interoceptive accuracy remained unchanged.

“The increased gastric interoceptive sensitivity by compression, in turn, predicted dampened risk-behavior. Post-hoc, we observed that this was mainly driven by women, as women showed increased interoception and reduced risk-taking, whereas interoception decreased among men,” the study authors explained. “These findings demonstrate how a body manipulation alters interoception, and this causally leads to behavioral change.”

However, the researchers note that their sample was not gender-balanced and they did not set out to investigate gender differences initially, so these specific findings should be interpreted with caution.

The study contributes to the scientific understanding of the psychological effects of body compression. However, it should be noted that the study was conducted on a relatively small number of individuals and risk-taking decisions did not carry real consequences for the participants. Results of studies on larger samples using risk-taking decisions with real consequences for participants might differ.

The paper, “Body core compression enhances interoception leading to altered risk choices,” was authored by Stefania Polzin, Anoushiravan Zahedi, and Soyoung Q. Park.