Follow Your Heart (No, Literally)
Many common phrases earn a refreshing new perspective when you think about them scientifically. My favorite example is the motivational phrase “think positive”. It’s a phrase that sounds a little vacuous because we hear it so often, but with the burgeoning science of mindfulness, it is beginning to look more like a fundamental life principle. I’m going to focus on another phrase here, but rather like “think positive”, it is also used in efforts to motivate: “follow your heart”. In normal usage, people say this to encourage a friend to commit to their passion: “don’t do what your brain says and take the boring office job, do what your heart says and become the rock star you’ve always wanted to be”. Well, unfortunately, sometimes life gives you so many lemons, that all the sugar in the world won’t be enough to make lemonade. But maybe there’s another more literal way to follow your heart.
As science progresses, we find increasingly interesting ways to map out the human condition. One particular trait that has attracted scientific study is known as “interoceptive awareness”. This is our ability to perceive and understand our own internal states. If I wanted to test your interoceptive awareness, I could hook you up to a heartbeat monitor, hide the screen from you, and then play ten auditory beeps that are either perfectly timed to each of your heartbeats, or slightly delayed from them. Each time I played a set of beeps, I would ask you, “did the beeps match your heartbeat?”. By testing your accuracy in answering these questions, I would understand the strength of your interoceptive awareness. In another test, I could also simply ask you to silently count your heartbeat over the course of a minute (you can’t cheat by taking your pulse!). The closer your guess to the true number, the better your interoceptive awareness.
When we focus on our heartbeat in these kinds of tasks, a specific network of brain areas becomes particularly active. This network includes our insula, an area buried inside the fold that separates our frontal and temporal lobes. The more activity we have in the right side of our insula, the better we are able to detect our heartbeat. And the same correlation holds true for the size of our insula: the more voluminous its gray matter, the better we perform.
Why is any of this important? Well, the quality of our interoceptive awareness correlates with a number of important functions. Some evidence shows that if we have more anxiety in our life, we are more accurate in monitoring our heartbeat, suggesting a link between the way we perceive our bodily states and the negative emotional states we experience. Our interoceptive awareness may also relate to how we process empathy. When we empathize with others after engaging an interoceptive mindset, we show greater activity both in our insula and in other empathy-related areas of our brain (e.g. the prefrontal cortex and cingulate cortex).
Some of us find it difficult to identify and describe our personal emotional experiences, and there is a name for this: alexithymia. Those of us with high interoceptive awareness have less alexithymia, so we are better able to understand our emotional states. We also experience fewer depression symptoms, which is unsurprising given that depression scores correlate with difficulties in self-directed emotional awareness.
Believe it or not, our interoceptive awareness may predict our chances of winning a game of “Simon Says”. You may have come across this game in elementary school. When the teacher declares “Simon says put your hand on your head”, and places their hand upon their head, then you should follow the instructions with your own hand. But if they only declare “Put your hand on your head”, without preceding it with “Simon says”, you should avoid the temptation to copy their action. This can be surprisingly difficult for kids, who are used to imitating adults and following their instructions. They frequently fail to stop themselves copying an action when they’re supposed to remain still.
Adults are not so great either, however. Although the “Simon Says” game is relatively straightforward in adulthood, we still maintain a basic impulse to mimic the actions of others during social interactions, at least on an unconscious level. So when researchers tested people’s automatic imitative behaviors, they found an interesting connection to interoceptive awareness.
Participants in their experiment watched a video featuring a human hand and some numbers. When the participants saw the number 1, they had to lift their index finger. When they saw the number 2, they had to lift their middle finger. But the hand on the screen also moved its fingers when the numbers appeared, and occasionally it would move the wrong finger. People were consistently slower to move their correct finger when the hand in the video moved the wrong finger, because participants had to suppress their urge to imitate the mischievous hand in front of them. Interestingly, the people who most struggled to suppress this automatic imitation urge were the people with the greatest interoceptive awareness. This could be thanks to their increased empathy activity in the brain, or perhaps their greater susceptibility to social anxiety, both of which I described earlier.
Could interoceptive awareness predict how we feel about our body? An illusion known as the “rubber hand illusion” tricks us into feeling as though a rubber hand is part of us. When someone touches our real hand that is hidden under a table, and also synchronously touches a visible rubber hand on top of the table, our brain makes sense of this confusing information by assuming the rubber hand must be our own hand. More specifically, we feel the touch on our real hand as coming from the rubber hand. The brain effectively says “I can feel my hand being touched, and all I can see is that rubber hand being touched in the same way, so that rubber hand must be my hand!”. People with strong interoceptive awareness are less susceptible to this illusion, probably because they have a more reliable sense of the contours of their own body. Their brains are not so easily fooled when it comes to body perception.
We can also look at how much we objectify our own bodies. When we speak of objectification, we normally talk about objectifying other people’s bodies. But our own bodies are not immune from our judgments about physical attractiveness. In one study, women with low interoceptive awareness objectified their bodies more severely. If low interoceptive awareness means that our attention has a primarily external rather than internal focus, then we may be more likely to visualize our bodies from a third-person perspective, which is fertile territory for self-objectification.
Studies that have looked at interoceptive awareness across the ages of ~20-70 have shown that our interoceptive awareness steadily declines with age. In a sense, our heart gets lost among the noise. At the moment, we know little about how much we can improve our interoceptive awareness, and know even less about whether improving it would have any major life benefits. You might expect that mindfulness and meditation practices could help with enhancing the accuracy of our internal monitoring, but the evidence is mixed at best. We’ll have to wait on further research before we fully understand how to train our interoceptive awareness, or whether it’s even worth training in the first place.
For now, we can be confident that there are some curious connections between our ability to look inwards and several of our personal qualities, from our empathy to the way we perceive our body. So next time someone tells you to follow your heart, you can offer a response that they weren’t expecting.