Can you feel your heartbeat? By Rebecca Prince

Whether it’s referring to love, a “heart of gold” or a “cold-hearted” individual, there are numerous examples throughout literature, film and our everyday lives where the heart is characterised only in the most emotional terms. Biology tells of a heart which is vital and functional, pumping blood around the body to deliver oxygen to our cells. If you’ve ever felt scared or anxious you’ve probably felt your heart speed up, so our emotions clearly have some effect on our hearts. But an emerging field of research suggests our hearts and emotions are more intertwined than we might think.

An article published in the New Scientist in October 2019 describes a curious phenomenon. A researcher called Sarah Garfinkel, speaking at a New Scientist Live event, discussed her research into how quickly drivers react to hazards. If the hazard appeared during the heartbeat itself rather than in between beats, drivers were slower to react to it. While the research simulated driving using a virtual reality game, it has implications for whether drivers crash or not in the real world.

As I read this article, I found the idea that our heartbeats have this potentially life-changing impact on our lives intriguing. The article goes on to describe Garfinkel’s past research, suggesting we feel pain less intensely, have poorer memory and can be more frightened during our heartbeats compared to in between them. It seemed that our heartbeats have a far greater influence on our lives than just pumping blood around the body. I started to delve into the research carried out by Garfinkel and her colleagues at the University of Sussex.

I soon realised that one word dominated the research - interoception.

Our brains are bombarded with signals all the time. They allow us to see and hear the world around us. But these signals don’t just come from the outside world. Do you notice when you are hungry, tired or your heart is racing? These are all examples of interoception; the sensations from within our bodies.

Sarah Garfinkel has researched interoception extensively over the past few years. She has discussed her work in talks, on the radio and was even named a rising star in science by Nature in 2018.

The term interoception was first coined over 100 years ago, but it has been used with increasing frequency since the millennium. While it refers to sensations from organs throughout the body, the heart has been prominent in research. Your heartbeat can easily be measured using a pulse oximeter, a probe which clips onto your finger, or by monitoring the heart’s electrical activity using an ECG.

Each heartbeat sends a signal to the brain. Researchers are interested in whether we are aware of this. One way they can do this is to ask people to tap when they feel their heart beating without feeling for their pulse. The researchers can then compare this to how often they know the heart is beating. If someone taps at the same rate as their actual heart rate, then they are very accurate at detecting their heartbeat, a concept called interoceptive accuracy.

It turns out high interceptive accuracy has its advantages. I hinted right at the beginning of this article at a close link between the heart and our emotions. In one study, researchers used pictures to try to trigger an emotional reaction. They found that people who were good at detecting their own heart rate were better at managing their emotions. This suggests that beyond each heartbeat, our overall awareness of our own heartbeats affects our mental wellbeing.

There’s another layer to this - how good someone thinks they are at detecting their heartbeat. While studying autism, Garfinkel and her colleagues found that people with autism thought they were much better at detecting their own heartbeat than they really were. Participants who had this mismatch were more likely to be anxious and were less emotionally sensitive. It is thought that teaching people with anxiety to be more attuned to the sensations from their body - more introceptively accurate - may be an effective treatment for anxiety.

Interoception is a fascinating area. It suggests our awareness of our heart is tied to our emotional state, and that any deficit in this awareness can affect our mental health. I have only just opened a small window onto this sphere of research. There is so much more to find out and new research to discover. I will certainly be keeping an eye out!

Sources:

https://www.newscientist.com/article/2219713-your-heartbeat-may-shape-how-likely-you-are-to-have-a-car-crash/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4876111/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4958623/

https://www.sciencedirect.com/science/article/pii/S2352250X17300106

https://www.sciencedirect.com/science/article/pii/S0301051115300958

https://www.sciencedirect.com/science/article/abs/pii/S0005796718301955

Image: Photo by Luan Rezende from Pexels

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