A recent study published in the journal Royal Society Open Science suggests that a popular method used to measure how well people sense their internal body signals might not actually relate to mental health conditions like anxiety or depression. The findings challenge previous assumptions and provide evidence that the widely used heartbeat counting task may not be an effective tool for psychological research. The researchers recommend that future work rely on alternative ways to measure internal body awareness.
Interoception is the nervous system’s ability to perceive and process information from inside the physical body. This complex bodily function includes everyday sensations like feeling a racing heart, a full stomach, or changes in breathing patterns. Scientists use various tests to measure how accurately a person can sense these internal physical signals.
“How the brain interacts with the rest of the body has been a popular scientific question for quite some time,” said Niall W. Duncan, associate professor at the Institute of Mind, Brain and Consciousness at Taipei Medical University. “In particular, people interested in mental health conditions have looked at how signals from the body might be influencing our conscious experience.”
Duncan explained that one common approach to studying this internal awareness involves asking participants to count their own heartbeats.
“One popular approach for studying how well people are able to sense what is happening inside their body has been to use a task where people are asked to count their heartbeats (unimaginatively called the heartbeat counting task),” Duncan said.
During this specific task, a person sits quietly and counts their own heartbeats over a short period without taking their pulse by hand. A person’s score on this test is based on how closely their mentally counted heartbeats match their actual recorded heartbeats. For many years, scientists have used this counting task to explore connections between internal body awareness and specific psychological traits.
Some research has linked poor heartbeat perception to clinical conditions like depression and severe anxiety. Another condition often studied in this context is alexithymia. Alexithymia refers to a psychological phenomenon where a person has severe difficulty identifying, understanding, and describing their own internal emotions.
Recent reviews of the psychological literature have produced highly conflicting results regarding these mental health links. Some analyses found strong associations between heartbeat tracking and mental health, while other reviews found no connection at all. These mixed results suggest that there might be underlying issues with how the data is currently collected or interpreted by professionals.
“However, there has recently been a lot of discussion about the validity of this task,” Duncan noted. “Is it really measuring what people had said it measured, namely the degree to which an individual is able to perceive signals from inside their body?”
Some experts argue that the heartbeat counting task is deeply flawed as a measurement tool. They suspect that participants might simply guess their heart rate based on how fast they think their heart usually beats, rather than actually feeling the physical thumps in their chest. Additionally, a person’s natural ability to estimate time might skew their heartbeat counting score. If someone knows their heart beats about once per second, they can just count the seconds in their head to get a perfect score.
The specific instructions given to participants can also heavily influence their performance on the test. For instance, when participants are told to only count heartbeats they are absolutely sure they feel, their accuracy scores tend to drop by half. Because of these methodological concerns, the authors aimed to test the validity of the heartbeat counting task.
“As I’m interested in more general questions of how science is done and of improving our methods, this task and its use in studies of mental health-related psychological constructs presented an interesting example,” Duncan said.
“Firstly, we were interested to know if the association between the task and these psychological constructs was likely to be real or not, based upon the totality of the available evidence,” he continued. “Since a lot of discussion of the role of bodily awareness in mental health has cited this assumed association, its robustness is important to know.”
Duncan pointed out that some older studies already suggested there is no real effect. The research team wanted to build on that existing knowledge by looking at newer data.
“That would be interesting from a meta-science point of view as people continuing to use this task even when evidence exists for its invalidity raises interesting questions about how change happens (or doesn’t happen) within some areas of modern science,” Duncan added.
To explore these inconsistencies, the researchers conducted two separate investigations. The first investigation was a behavioral study involving exactly 79 human participants. The sample included 45 females and 34 males, and the average age of the participants was about 27 years old. All participants were completely healthy, with no recorded history of neurological, psychiatric, or cardiac conditions.
The participants completed three established psychological questionnaires at the start of the experiment. They took the Beck Depression Inventory-II to measure any underlying depressive symptoms. They completed the trait scale of the State-Trait Anxiety Inventory to assess their baseline levels of daily anxiety. Finally, they filled out the Toronto Alexithymia Scale to measure their ability to recognize and describe their complex emotions.
The researchers also measured each participant’s height and weight to calculate their body mass index. Body weight can sometimes affect heartbeat perception because thicker layers of bodily tissue can make it harder to feel subtle internal movements. Next, the participants completed the actual heartbeat counting task. They sat comfortably with their feet flat on the floor and their hands resting on their knees.
They were hooked up to a three-lead electrocardiogram, a medical device that records the electrical signals of the heart using sensors placed on the left and right forearms and the left ankle. The researchers gave them very strict instructions to only report the heartbeats they genuinely felt, rather than guessing. The participants completed seven blocks of the task, with each block containing three separate counting intervals lasting 25, 35, or 45 seconds. The trials were presented in a random order with a short five-second pause between each one.
The researchers compared the participants’ reported counts to the actual electrocardiogram recordings to determine their exact accuracy scores. The results showed no meaningful association between the heartbeat counting scores and any of the three psychological questionnaires. While twelve participants were classified as overweight, their body mass index did not affect their performance on the task. Even when the researchers removed participants who displayed mild symptoms of anxiety or depression from the statistical analysis, the results remained completely unchanged.
Following the behavioral study, the researchers conducted a comprehensive meta-analysis. A meta-analysis is a statistical technique that combines the mathematical results of many different independent studies to look for broad, overall trends. The researchers gathered data from 78 distinct experiments across 70 published academic articles. They specifically looked for prior studies that used the heartbeat counting task alongside the exact same three psychological questionnaires used in their behavioral study.
The meta-analysis revealed no association between heartbeat counting performance and symptoms of depression or alexithymia. The researchers did find a very weak positive correlation between heartbeat counting accuracy and trait anxiety. However, this weak link seemed to be heavily moderated by the type of instructions given to the participants.
Studies that used the original, less strict task instructions showed a slight correlation. Studies using the updated, strict instructions showed no correlation at all. This provides evidence that the phrasing of task instructions can artificially alter the results.
The meta-analysis also highlighted significant systemic problems within the existing psychological literature. The researchers found no evidence of publication bias, which happens when academic journals only publish studies with positive or exciting results while ignoring failed experiments. However, they discovered that the included studies consistently suffered from extremely low statistical power. This means the previous studies used sample sizes that were far too small to reliably detect true psychological effects.
The median statistical power of the evaluated studies was only around six to seven percent. None of the 78 experiments had enough statistical power to accurately identify the tiny effect sizes found in the final meta-analysis. Readers should be cautious not to misinterpret these specific findings as absolute proof that internal body awareness has no connection to mental health. The study simply suggests that the heartbeat counting task is an ineffective way to measure that complex connection.
“In terms of the heartbeat counting task and its association with the psychological constructs we included, our work shows quite strong evidence that how people perform in the task is not related in any meaningful way to their reported anxiety or depression-like symptoms,” Duncan told PsyPost.
“This doesn’t mean that feelings of anxiety or depression aren’t related to how a person senses input from within their body, just that this particular task isn’t useful for studying that,” he continued. “Establishing that fact helps drive development of new and better methods, which is already happening, which in turn means we can improve our theories.”
There are some limitations to consider. The meta-analysis was not pre-registered. Pre-registration is a common scientific step that typically helps prevent researchers from accidentally shifting their analysis plans after seeing the raw data.
Additionally, the researchers only looked at three specific psychological questionnaires to maintain data consistency. The results might not apply to other tools used by doctors to measure anxiety, depression, or alexithymia.
Finally, the researchers noted a high level of differences among the participants in the meta-analysis. Variations in male-to-female ratios, different clinical diagnoses, and different test durations could have muddied the combined data. Future research should focus on developing and rigorously testing better ways to measure internal body awareness. Scientists might explore different types of cardiac tests that do completely away with mental counting or time estimation requirements.
They could also look into other bodily signals entirely. For example, researchers could measure how well people perceive their own breathing rhythms or monitor changes in their gastric and stomach activity. Finding more reliable measurement tools will help scientists better understand how our physical bodily sensations directly interact with our ongoing emotional well-being.
“I think our work is a good illustration of how the scientific process works,” Duncan said. “People will make some initial findings and then over time other people will test the idea in different ways and produce more evidence.”
“Eventually we can get to a place where we can bring all the evidence together and make more robust claims about the world,” he concluded.
The study, “Testing the correlation between the heartbeat counting task and anxiety, depression and alexithymia scales: a behavioural study and meta-analysis,” was authored by Evgeny A. Parfenov, Elizaveta Baranova, and Niall W. Duncan.
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