Much like the taste of cilantro, the way we feel pain is not one-size-fits-all.

Sometimes, we might feel pain from an injury more intensely than expected. Other times, a similar injury won’t hurt as much.

Now, a new study from Japanese researchers explores why that is by looking at how our expectations and uncertainty about a situation can influence the pain we experience.

Two theories help explain how the brain processes pain: the Estimate Hypothesis and the Surprise Hypothesis.

The Estimate Hypothesis suggests that the brain “guesses” what sort of pain intensity is appropriate. The Surprise Hypothesis says pain is perceived as the difference between what we expect to occur and what actually occurs. Think of a time you expected to stub your toe hard, only felt a glancing blow, but yelled anyway.

Scientists used these hypotheses to examine how the brain responds to pain when the element of surprise is introduced.

In the study, healthy participants were exposed to pain in the form of heat while they used virtual reality goggles to view painful or non-painful scenarios.

When a visual threat, such as a knife, unexpectedly disappeared in some scenarios, pain intensity increased significantly. Especially when the difference between prediction and reality was large — indicating that the Surprise Hypothesis better explains how we perceive pain.

In short: The greater the discrepancy between expectation and reality, the worse our pain feels. That means shrinking the gap between pain expectation and “surprise” is important in reducing pain.

So when your doctor says “you’ll feel a small pinch,” let’s hope she’s right.