Gladwell says “epidemics are sensitive to the conditions and circumstances of the times and places in which they occur.”

The most controversial idea cited is the Broken Windows Theory, which posits that crime is an outgrowth of disorder. So if you clean the graffiti off of subways and the trash off the streets and repair any actual broken windows, it will create an environment in which people are less likely to commit crimes.

It’s still being debated.

Larry Marano / Getty

In “Blink,” Gladwell zooms in on “thin slicing,” a psychological process in which we’re constantly reading people’s personalities within seconds of seeing them.

Examples of thin slicing include:

• We predict how likely someone is to get a promotion based on the person’s clothes.

• We infer whether someone is gay or straight from glancing at his or her face.

• We think a woman is promiscuous if she has a visible tattoo.

Steven Depolo / Flickr

Elsewhere in “Blink,” Gladwell discusses priming, a psychological phenomenon in which a subtle suggestion can cause people to act or think in a certain way.

He draws on the work of Yale psychologist John Bargh, whose experiments have shown that people walk slower after they have read lists of words associated with elderly people, like wrinkle, bingo, and Florida.

Frazer Harrison / Getty

In “Outliers,” Gladwell reported on the 10,000 Hour Rule, a construct for understanding expertise that became such a part of the culture that Macklemore wrote a self-affirming song about it.

The rule states that it takes 10,000 hours of deliberate practice to become an expert in any field.

It comes from the research of Florida State University psychologist K. Anders Ericsson, who studied chess masters and tennis players.

Jerry Lai-USA TODAY

In “Outliers” Gladwell discusses the Matthew effect, which takes its name from a Bible verse — “For whoever has will be given more, and they will have an abundance. Whoever does not have, even what they have will be taken from them.”

Put another way: advantage accumulates.

Gladwell found that the top hockey players were born in the first part of the year. While the date of your birth is inconsequential when you’re 25, it matters when you’re 5 — the kids born in January were bigger, stronger, and more ready to be stars, so their coaches developed their skills accordingly.

That realization has led to academic “redshirting,” where parents will hold back their kids a year so they can outcompete their peers.

Frederick M. Brown/Getty Images

Raw intelligence doesn’t guarantee success.

You need opportunities to open up for you to succeed.

In “Outliers,” Gladwell uses the case of Bill Gates and The Beatles to build his case.

When the Microsoft founder was a boy growing up in Seattle, he had access to computers that almost no other teen in 1968 would have had — giving him a leg up on everybody else. Gladwell finds an analog in The Beatles, who were brought in to clubs in Hamburg, Germany, to play shows for hours upon hours and thus had the ability to hone their live act.

AP Photo/Michael Dwyer

In his newest book, “David and Goliath,” Gladwell tinkers with social conceptions of advantage and disadvantage.

He discusses “relative deprivation” in one section, asserting that going to an Ivy League school or prestigious company can be counterproductive for high achievers, because they are less likely to succeed in the competitive crush of Harvard or Goldman Sachs.

“Rarely do we stop and consider,” he writes, “whether the most prestigious of institutions is always in our best interest … The Big Pond takes really bright students and demoralizes them.”

Paul Kane / Getty

What do Richard Branson, Charles Schwab, and Ted Turner have in common? Aside from being rich white men, they’re all dyslexic.

In “David and Goliath,” Gladwell argues that the condition can be an advantage.

“Dyslexia — in the best of cases — forces you to develop skills that might otherwise have lain dormant,” he writes.

It helped Branson guide Virgin, the superbly branded company he founded in 1970 that is now bringing in $24 billion in revenue a year.

“My dyslexia guided the way we communicated with customers,” Branson reflected. “When we launched a new company, I made sure that I was shown the ads and marketing materials … If I could grasp it quickly, then it passed muster.”