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Q&A: Sarah Garfinkel, consciousness researcher, on your sixth sense

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Can you detect your own heartbeat? If so, you may have the power of interoception and even have a richer emotional life. Here's how to find out.

There's a new area of scientific study that has uncovered a skill that could be considered our sixth sense. It's called interoception and it's the ability to monitor your own internal organs. For instance, how interoceptive you are can be measured by your ability to accurately count your heart beat, by just tuning into it.

So it's a skill, or talent, that involves being quite in tune with one's body. And this ability is associated with some interesting and useful traits. Those who are highly interoceptive are also highly intuitive and aware of their "gut" feelings. They also apparently have a better memory for emotional information and are more emotional overall. Awareness of one's emotional and physiological state may also reward people with an ability to control it. For instance, one study has found that those who have good interoceptive ability are also less anxious when speaking in public.

SmartPlanet caught up with Sarah Garfinkel, a post-doc researcher at the Sackler Centre for Consciousness Science at the University of Essex, and asked her to explain interoception, how it is measured and how one might be able to improve their own interoceptive ability.

SmartPlanet: How do we measure interoception? Or in the case of heart rate, how do we count our heart beats?

Sarah Garfinkel: Heartbeat is the measurement of interoception that I've been interested in. There are two ways to test people's ability to count their own heartbeat. You give set periods of time and you have people count how many heartbeats they’ve perceived in that space of time.

The other way people have done it is to present tones or some sort of external signal, like a flashing light, and the tones exactly match the beating heart, or they’re time-shifted slightly and people have to say whether the tones are in sync or out of sync with their heartbeats.

That sounds hard.

It’s really hard. The majority of people, maybe 80 percent of people can’t tell if their heart beat is in sync with the tones. It’s so difficult because it involves integrating an outside signal with an inside process. People tend to be better at counting their heart beats [within a specific time frame.] Because most can do it, the counting one gives a really lovely spread of sort of bad, intermediate and good.

So some people are good at it, some people are bad at it. How do people typically try to count their heart beat? Most of us only “feel” our heart beat when it races during exercise or a highly emotional event.

So just to clarify, [the test] always happens at rest. Because you are right, if you’re doing physical exercise or if we scare anyone beforehand then everyone will have an enhanced ability to detect a heart beat.

To measure their accuracy we create a ratio of actual heart rate relative to perceived rate. So a ratio of one would be perfect. A ratio of 0.7 is considered good.

Are some types of people better than others, on average?

Yes, fitter young men tend to be very good. Fitness is an indicator, one of the many indicators of whether you’re good or bad.

What is another indicator?

Age. People get worse as they get older. Although heartbeat perception is considered a stable trait, age has a declining effect on it.

You’ve mentioned before that there is an association between interoception and the ability to remember emotions. How do we even know this?

I love these sorts of experiments. They just blow my mind. First of all, people who are more interoceptive tend to have a richer emotional experience.

If you record people’s physiological responses or get them to rate emotional pictures, people with higher interoception will rate them as more emotionally intense.

Why is this?

Well theories of emotion, such as the James-Lange theory of emotion, state that fear or emotion perception arises from the detection of changes of internal bodily sensations.

So the emotion itself is “the noticing of a physical change” in one’s body?

Yes, some argue emotions arise from the detection of changes in the body. It reminds us of the famous question from William James: Do you run from the bear because you’re afraid, or are you afraid because you run?

And he would argue that you’re afraid because you run because you feel all the physiological changes of the body. So if you then extrapolate from that: Those people who are better able to detect physiological changes [e.g., heart rate changes] they are going to report the experience as being more emotional.

This makes sense.

We tend to remember something if it’s more emotional. But now people with interoception find things more emotional. So this can suddenly start impacting our cognitive processes. And why they tend to remember emotions.

Apparently those who are highly interoceptive also have better intuition?

At the Sackler Centre for Consciousness Science, we are interested in what it means to have conscious knowledge.

Our gut instinct, or intuition, is where you know something is right but we just don’t know why. But everything in one’s gut tells us that it’s right. This is because your body can also hold information.

How?

Right. What gives rise to that feeling of knowing? It can be represented in the autonomic nervous system, so your body can have an enhanced arousal response. Like a sweat response. Or your pupils can also change size, they can dilate. And this can happen with regard to true information or previously encountered experiences.

And then the degree to which you can articulate or know you know it is an extra level of consciousness. So if you believe this premise that our body reacts to things and reacts to things correctly, and that can happen detached from your conscious awareness, then that means that those people who are better able to tap into those autonomic bodily channels are better able to use that as a cue to guide them.

On one hand we’ve heard these things anecdotally over and over again. That is “gut instinct.” But now science is putting this structure around it.

I know, I love it. I really love it. We’ve all had this experience where you bump into someone and you know you know them. Everything in your body says that you’ve had an encounter before, but you can’t recall when or where. But you feel it. And now we’re able to understand that those who are interoceptive are better at detecting [the gut feeling.] It’s been shown experimentally.

Also I have heard that interoceptive people have less anxiety speaking in public than the rest of us?

Yes that is from a published experiment. But that experiment was slightly contrary to all the other body of experiments that have shown that those with high anxiety tend to be interoceptive.

So why do you think this study showed less anxiety speaking in public?

Well if you are aware of how your body is changing and you can feel it and predict it, then that does potentially make it more manageable.

So it's the idea that if you are aware of something you can control it more?

Yes. I published a study this year with Hugo Critchley called, “What the Heart Forgets.” We show that if you process words when your heart is beating -- meaning exactly when your heart beats, as opposed to the off-beat, you’re less able to remember words that were presented when your heart beats. It has an interference effect if you see a word exactly during a heart beat. You forget them much more easily.

However, if you are interoceptive you are good at detecting your internal bodily signals, and better able to eliminate the interferences effect of heart beats on memory.

This fits with the idea that if you are able to detect a bodily process and you’re more able to protect against its interfering or detrimental influences.

That is amazing. You’ve mentioned that people can be trained to get better at interoception. How?

Based on our own observations, there is a potential in some people to learn. Because people sometimes don’t know what to focus on. For example, I was terrible when I started. I kept trying to focus on my chest. And actually people don’t necessarily feel their heart beat in their chest. They can feel it in other parts of their body.

So once you’re aware of that, then you can start focusing on other parts and maybe then you’ll be more sensitive to a signal. That is where the training component can come in. But that might only true for people who have the ability to tap into the signal but just don’t know where to focus. Whereas there are others who can never feel the signal, it doesn’t matter where they’re focusing on.

I have heard that biofeedback can sometimes help people tap into interoceptive ability.

Yes this is based on a process by Yoko Nagai. Basically people can watch a caterpillar move on a screen, and their body is wired up to a device that measures their skin conductance [which measures sweat as a signal of arousal]. When you’re relaxed the caterpillar will go in one direction and when you’re not relaxed the caterpillar will go in another direction.

This is based on the premise that people may think they’re in a relaxed state, but actually their body is not relaxed. So having this external manifestation of bodily states can help potentially train people to understand what it really means to have your body in a relaxed state or not.

So they get a sense of it, of what “relaxed” is supposed to feel like.

Yes, exactly. So that even if they may be bad at understanding their internal bodily process, they can learn it based on external cues and then emulate it in the future.

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Christie Nicholson

Contributing Writer

Christie Nicholson produces and hosts Scientific American's podcasts 60-Second Mind and 60-Second Science and is an on-air contributor for Slate, Babelgum, Scientific American, Discovery Channel and Science Channel. She has spoken at MIT/Stanford VLAB, SXSW Interactive, the National Science Foundation, the National Research Council, the Space Studies Board and Brookhaven National Laboratory. She holds degrees from the Columbia University Graduate School of Journalism and Dalhousie University in Canada. She is based in New York. Follow her on Twitter. Disclosure