Donald Trump can change the temperature of a room with a sentence. One minute he is certain, the next he is backtracking. One day he is threatening, the next he is hinting at a deal. Even before anything concrete happens, people brace for his next turn.
That reaction is not just political. It is what unpredictability does to any system that requires stability. To act at all, you need some working sense of what is happening and what is likely to happen next.
One influential framework in brain science called predictive processing suggests the mind does not wait passively for events. It constantly guesses what will happen, checks those guesses against reality, and adjusts.
A brain that predicts can prepare, even when what it prepares for is uncertainty.
The gap between what you expect and what actually happens is known as a prediction error. These gaps are not mistakes but the basis of learning. When they resolve, the brain updates its picture of the world and moves on.
This is not about what anyone intends, but about what unpredictability does to systems that need some stability to work. Trouble starts when mismatches do not resolve because the source keeps changing. People are told one thing, then the opposite, then told the evidence was never real.
The brain may struggle to settle on what to trust, so uncertainty stays high. In this view, attention is how the brain weighs up what counts as best evidence, and turns the volume up on some signals and down on others.
Uncertainty can be worse than bad news
When this keeps happening, it’s hard to get closure. Effort is spent checking and second guessing. That is one reason why uncertainty can feel worse than bad news. Bad news closes the question, uncertainty keeps it open. When expectations will not stabilise, the body stays on standby, prepared for many possible futures at once.
One idea from this theory is that there are two broad ways to deal with persistent mismatch. One is to change your expectations by getting better information and revising your view. The other is to change the situation so that outcomes become more predictable. You either update the model, or you act to make the world easier to deal with.
On the world stage, flattery can be a crude version of the second route, an attempt to make a volatile person briefly easier to predict. Everyday life shows the same pattern, such as unpredictable workplaces. When priorities change without warning, people cannot anticipate what is required. Extra effort may go into reducing uncertainty rather than doing the job.
Research links this kind of unpredictability to higher daily stress and poorer wellbeing.
The same pattern shows up in close relationships. When someone is unpredictable, people scan tone and try to guess whether today brings warmth or conflict. It can look obsessive, but it is often an attempt to avoid the wrong move.
Studies link unpredictable early environments to poorer emotional control and more strained relationships later in life.
The strain does not stay in thought alone. The brain does a lot more than thinking. A big part of its work is regulating the body, such as the heart rate, energy use and the meaning of bodily sensations.
It does this by anticipating what the body will need next. When those anticipations cannot settle, regulation becomes costly.
Words matter here in a literal sense. Language does not just convey information. It shapes expectations, which changes how the body feels.
Trump can do this at a distance. A few words about a situation can raise or lower the stakes for people, whether in Minneapolis or Iran. The point is that signals from powerful, volatile sources force others to revise their models and prepare their bodies for what might come next.
Communication is a form of regulation. Clarity and consistency help other people settle. Volatility and contradiction keep them on edge.
When a single voice can repeatedly unsettle expectations across millions of people, unpredictability stops being a personal stress and becomes a collective regulatory problem.
How to deal with unpredictability
So what helps when unpredictability keeps pulling your attention? Try checking for new information if it changes your next step or plan, otherwise it just keeps the uncertainty alive.
When a source keeps changing, reduce the effort spent trying to decode it. Switch to action. Set a rule that makes the next step predictable. For example, read the news at 8am, then stop and get on with your day.
Learn where not to look. When messages keep reversing, the problem is not a lack of information, it is an unreliable source.
Biological systems survive by limiting wasted predictions. Sometimes that means changing your expectations; sometimes it means changing the situation. And sometimes it means accepting that when Donald Trump is talking, the safest move is to stop trying to predict what comes next.
Robin Bailey does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.
