All social classes have unspoken rules.

From A-list celebrities to teachers, doctors, lawyers, and journalists — there are social norms that govern our decisions, whether we realize it or not.

Researcher Elizabeth Currid-Halkett studies social networks, and has observed certain patterns across swaths of American culture. In her book Starstruck: The Business of Celebrity, she looks at the super elite: the celebrities who populate the Hollywood Hills and the tabloids in our grocery stores. She makes a distinction between fame and celebrity.

"Fame is simply people knowing who you are," she says. "The sheer number of people who know who someone is, is very different from a public being fixated upon someone." For example, we all know who Bill Gates is — but we aren't all wondering what Bill Gates ate for breakfast today, the way we might wonder that about Beyoncé, or Barack Obama, or Jennifer Aniston.

This week on Hidden Brain, we look at the invisible qualities that all celebrities have in common, and how our interest in them builds because of cues we get from one another. Later in the episode, we look at another elite group: the yoga-loving, Whole Foods-shopping, highly-educated group that Elizabeth Currid-Halkett calls The Aspirational Class.

Copyright 2017 NPR. To see more, visit http://www.npr.org/.