That’s not what negative feedback means

On January 30, NPR’s All Things Considered ran a segment called How The Trump Administration’s Tariffs On China Have Affected American Companies. In it, NPR’s Ari Shapiro was asking questions of Bloomberg reporter Andrew Mayeda. There was this exchange.

SHAPIRO: When you look at the scale of the impact, is this more along the lines of an annoyance and inconvenience, or is it a real economic impact, something that could lead to slower economic growth, maybe even a recession down the line? How severe is it?

MAYEDA: If you actually look at the big-picture forecasts of the impact – for example, the IMF says that if we have a worst-case trade scenario, the global economy is going to be less than 1 percent smaller than what it otherwise would’ve been. That is not catastrophic. I think what people are concerned about is that there’s some type of confidence shock. That is to say that, you know, businesses start investing less. Consumers start spending less. And it gets into this negative feedback loop where reducing confidence leads to slower growth.

Hate to tell you this, Mr. Mayeda, but what you describe here is a positive feedback loop.

Negative feedback occurs when some function of the output of a system, process, or mechanism is fed back in a manner than tends to reduce the fluctuations in the output.” Furthermore:

Whereas positive feedback tends to lead to instability via exponential growth, oscillation or chaotic behavior, negative feedback generally promotes stability. Negative feedback tends to promote a settling to equilibrium, and reduces the effects of perturbations. Negative feedback loops in which just the right amount of correction is applied with optimum timing can be very stable, accurate, and responsive.

Sadly, this isn’t the only instance I’ve encountered recently of reporters misusing the term. In all cases, reporters are characterizing the feedback as negative or positive based on the outcome. To them, if the outcome is bad, then it’s a negative feedback loop. If the outcome is good, then it’s a positive feedback loop. That’s not the way it works.

Negative feedback loops typically lead to stable systems: generally a positive result. A positive feedback loop tends to result in a system fluctuating wildly or going completely out of control: a generally negative result.

Reporters, please do a little research before using terms that you’re not familiar with. It’ll save you a lot of embarrassment, and prevent you from confusing people.

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