Sometimes Bad News Is Better

Or, how to spot a bad dentist

When a rat experiences mild electric shocks, similar to the static shock you might get from brushing your foot on a carpet, it naturally becomes stressed. Its heart rate increases, and it secretes more stress-related hormones (called glucocorticoids). This stress makes the rat very likely to develop an ulcer.

But if you take another rat and tweak this experiment slightly such that just before each shock the rat hears a warning bell, it leads to fewer ulcers.

Predictability makes stressors less stressful, even if the prediction is bad.

The rat with the warning basically gets two pieces of information. When it hears the warning bell, it learns when something dreadful is about to happen, so it prepares itself. The rest of the time, it learns that something dreadful is not about to happen, so it relaxes.

But the rat without a warning is always a half-second away from the next shock.

Basically, the warning bell before the shock tells you that there’s bad news coming for sure, things are gonna get worse, but it’s all gonna happen at a predecided time, and it’s never gonna sprung on you without warning. That’s a relief.

We all know a human equivalent of this principle: you’re in the dentist’s chair, no anaesthesia, and the dentist is drilling away. Ten seconds of nerve-wracking pain, some rinsing, five seconds of drilling, a pause while the dentist fumbles a bit, fifteen seconds of drilling, and so on. In one of the pauses, frazzled and trying not to whimper, you gasp, “Almost done?”

“Hard to say,” the dentist mumbles, returning to the intermittent drilling.

Think how grateful we are to the dentist who instead says, “Two more and we’re done.” The instant the second burst of drilling ends, down goes blood pressure. By being given the news about the stressors to come before the drilling, you are implicitly comforted by the assurance that the stressors are not coming anymore after the second burst of drilling ends.

Interestingly, organisms also have a peculiar habit of habituating to a predictable stressor if it is applied over and over. Even if the stressor still disrupts their physiological balance, the familiarity and predictability of the stressor result in smaller stress levels.

For example, when military men undergo parachute training, the stress level is significant initially, but as they become more and more familiar with the training, their anticipatory stress diminishes. (My sources say Tom Cruise experienced something similar during the shoot of MI: Dead Recking Part I as he jumped from the cliff several times.)

But stress can also occur even without any stressor. The mere loss of predictability is sometimes enough. For example, when a rat is placed in a cage and periodically receives food through a chute, it results in a consistent reward. However, when the pattern of food delivery becomes random — with the same total amount of food given but at unpredictable intervals — the rat’s glucocorticoid levels increase.

This occurs even though there are no physical stressors present in the rat’s environment. Something similar happens when you use social media apps — you never know when you’re gonna get a like, a subscribe, or a comment.

Loss of predictability triggers stress.

Stress can occur even when the external circumstances are less stressful. Let’s consider two migrating bird species. Bird #1 is in the Arctic, where the temperature is typically -15 degrees. And luckily, it is indeed -15 degrees today as well.

On the other hand, Bird #2 is in the tropics, where the average temperature is 30 degrees. However, today, the temperature has dropped to 15 degrees. Surprisingly, Bird #2 experiences greater stress.

It’s not because the temperature in the tropics is 30 degrees warmer than in the Arctic. It’s because the temperature in the tropics is unexpectedly 15 degrees colder than what was anticipated by the bird. Result: stress.

This example illustrates that the magnitude of the stress level can be influenced by deviations from expected conditions, even if the absolute level of stressors is lower.

A human version of the same idea was observed during the onset of the Nazi blitzkrieg bombings of England, when London was hit every night like clockwork. Lots of stress naturally. But unlike in the city, the bombings were far more sporadic in the suburbs, occurring perhaps once a week. Fewer stressors, but much much less predictability.

As a result, there was a significant increase in the incidence of ulcers during that time, but mostly among the suburban population.

Despite the similarity between the stress response in humans and in other animals to a lack of predictability, they are not identical, and in a very important way.

The warning of impending shocks to a rat has little effect on its stress level during the shocks, but it does make the rat more confident about when it doesn’t have to worry about the shocks, which in turn reduces its anticipatory stress outside of those moments.

Analogously, when a dentist says, “Only two more times and we’re done,” it not only allows us to relax at the end of the second burst of drilling, but (unlike the case for the rat) this information about an impending pain also lowers our stress level during the pain.

For example, if you were told “only two more times” versus “only ten more times,” wouldn’t you use different mental strategies to try to cope with the pain? In each scenario, you would rely on the reassuring thought of “only one more and then it’s the last one” at different moments. You would most likely save your most distracting thoughts for specific points. You might also try counting to zero from different numbers at different points. Having predictive information helps us determine the most effective coping strategy during a challenging situation.

We often wish for information about the course of some medical problem because it aids our strategising about how we will cope. A simple example: you have some minor surgery, and you’re given predictive information — the first post-surgical day, there is going to be a lot of pain, pretty constant, whereas by the second day, you’ll just feel a bit achy. Armed with that information, you are more likely to plan on watching Seinfeld on day one and to devote day two to writing delicate haikus than the other way around.

In a similar fashion, among other reasons, we also wish to optimise our coping strategies when we request the most devastating piece of medical information any of us will ever face: How much time do I have left?

Ideally, we wouldn’t want to be in such a dire conundrum, but when we are, bad news is often better than no news.