NPR.

This is Planet Money. I'm Stacey Vannick-Smith.

Today on the show, we have two stories from Planet Money's Daily Podcast, the indicator.

So a lot of us have a kind of naive view about ourselves.

We like to think we are in control of what we like and the choices we make.

We don't always think about the messengers and influencers who spend their days trying to shape the decisions we make

about what we buy and what we put into our bodies.

Today on the show, don't shoot the messenger.

From vaccines to skinny jeans, the sometimes unlikely people and forces that shape our economy,

what we buy, and ultimately our lives.

Here's the show.

Katie Milkman is a professor of operations, information, and decisions at Wharton.

And the author of this book had a change, the science of getting from where you are to where you want to be.

And she says, when news of the COVID vaccine first broke and everyone was talking about cold storage supply chains and transportation issues,

she and her team of behavioral scientists and economists immediately thought of something else.

We looked at each other and we said,

there's one other thing you are thinking about.

We have to convince people to take them.

So we decided we were going to devote our attention to that.

And we built sort of the biggest study that I think has ever been done quite quickly on figuring out what kind of messaging would be most effective on vaccination.

Katie's team decided they were going to put together this study.

They got together with Walmart, Northeast Penn Medicine, and Geisengar Health,

...