How much pain can humans really endure?

What is pain threshold and pain tolerance?

At its most basic, pain is a wake-up call that some damage may be happening to your body and prompts you to take action.

Pain threshold is the time at which you start to feel pain from a sensation. For example, clamping your wrist with a clamp will not cause immediate harm. However, as the pressure builds, you may experience discomfort and then pain. Your pain level is your pain threshold pressure.

We can also tolerate some pain, but we all have a limit. The point at which pain becomes unbearable is the person's pain tolerance.

Photometry and how we measure pain

Pain threshold and pain tolerance are both arbitrary and not measured on some scale. How do we quantify that being punched is more painful than being pinched?

So, to quantify pain, Cornell University researchers Hardy, Wolff and Goodell designed an experiment in which they burned themselves once for three seconds. After repeatedly burning three unfortunate subjects (more than 100 times, in fact), they asked the subjects to report the amount of pain they felt using a scale.

They created a unit of pain measurement (dol) based on the Latin word dolor (pain). A dol is the only noticeable difference between one pain intensity and another. Based on this, they created a 0-10 scale.

Many subjects with second-degree burns reported a pain level of 8. Any pain measurement above 11 dol is considered "difficult to discern." In other words, the pain was too excruciating for the study subjects to even quantify. This method of measuring pain sensitivity is called photometry.

This unit of measurement never really caught on in the scientific community. First, almost no one has been able to reproduce their results. Secondly, pain is a subjective experience that depends on a person's emotional state, psychological outlook, gender, age and genetics at the time.

This is why doctors' offices still use smiley faces (of which there are many types, too) when asking you how you're going through a lot of pain. If you say, "About 3.5 dol," the doctor may have no idea what you mean, but when you point to an animated face with a frown on its face and tears in its eyes, the doctor gets it.

As mentioned above, physical, psychological, and genetic factors all influence humans' subjective perception of pain, making precise quantification and comparison nearly impossible.

Brain's perception of pain affects how much pain a person can tolerate

As a child, imagine your parents protecting you from every possible danger. If you've never experienced a sprained ankle, black eye, or broken bone, you probably have a lower pain threshold. Another child who scrapes a knee, sprains an ankle, and wears a cast while growing up may develop a higher tolerance for pain. Once you've broken a few fingers off your skateboard, a bruised elbow doesn't seem so bad, right?

This experience is backed up by research, sometimes in strange ways. During World War II, Henry Beecher discovered that wounded soldiers suffered less than wounded civilians because injuries were less painful for soldiers than in war.

Plausibly, athletes and dancers have been found to have higher pain tolerance than writers who sit hunched over a computer all day.

Even stranger, if your brain thinks there is no pain, then you no longer feel pain. This is called the placebo effect, and it doesn't just apply to pain. This is the power of belief in bodily sensations, including pain. So the "mind over matter" attitude in some cultures makes sense, even if it's in a roundabout way.

But, of course, the brain is complex, and we're still not sure how it processes pain.