How your body shapes your feelings

In 1974, the psychologists Donald Dutton and Arthur Aron sent a young woman to interview men crossing two bridges in Vancouver. One was the Capilano Suspension Bridge, a narrow walkway that sways about 70 meters above a rocky river. The other was a solid, low bridge further upstream. After the interview, she gave each man her phone number, in case he wanted to hear more about the study.

Half the men she met on the swaying bridge called her afterward, against about one in eight of the men on the solid one. Their pounding hearts, it seems, had been read partly as attraction to her.

It's one study, and effects like it aren't always found. But the idea behind it is well supported: your brain doesn't always know why your body feels the way it does, and it fills in a reason.

Your brain keeps constant track of your heart rate, breathing, blood sugar, temperature, gut and more. This sense of the inside of your body is called interoception. Most of it never arrives as a clear message. It shows up as a general sense of feeling fine or off, wired or flat.

These signals don't come labeled, so the brain explains them using what's around: where you are, what just happened, what you were already worried about. Some researchers, notably Lisa Feldman Barrett, argue that this is how every emotion is built. That stronger claim is still debated. The weaker one isn't: the state of your body colors how you feel, and the two get mixed up.

Hunger is the everyday example. In one set of experiments, hungry people who sat through a frustrating computer task, rigged to crash, rated the researcher as more judgmental and felt more hateful than people who had eaten. There was one exception: hungry people who had first been asked to pay attention to their own emotions. Noticing their state was enough to stop the hunger coming out as anger.

When a feeling seems bigger than its reason, it's worth asking what your body is up to. The usual suspects:

• Too little sleep
• Not eating for hours
• Too much caffeine, or alcohol the night before
• Coming down with something, or in pain
• Hormonal changes, such as the days before a period
• Sitting still, indoors, all day

None of this means your feelings are "just" your body. A real problem and an empty stomach can turn up at the same time. It means your body is one of the places to look, and usually the quickest to fix.

It's 4pm and Mei skipped lunch. She reads a short email from her manager, "Can we chat tomorrow?", and is suddenly sure she's in trouble. What's most useful?