This is Hidden Brain, I'm Shankar Vedantam.

When psychologist Robert Chaldeenie was in college,

a magazine salesman knocked on his dorm room door.

He was selling subscriptions to Sports Illustrated magazine.

Bob was going to say no, but then the salesman said,

it's the most popular subscription here in your dorm.

And the experts rated as the number one sports magazine in the United States.

And I found myself buying that subscription.

The exchange with the Sports Illustrated salesman, God Bob Thinking,

what exactly had the man said to overcome his resistance?

And could studying exchanges like this reveal

why some people were more persuasive than others?

But I don't know I had the terms to explain it.

But I knew that they had worked and I knew that he had turned a note to a yes.

So there was something powerful there inside what he had said.

Over the course of several decades of observation

and experimental research at Arizona State University,

Bob eventually identified seven techniques of influence.

Last week on the show, we explored three of them.

We looked at the role of scarcity, the norm of reciprocity,

and the effects of liking.

If you missed that episode, I would strongly recommend you go back and listen to it first.

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