Prime Day stokes the fires of consumption among bargain-hungry shoppers. But it’s not just the prospect of saving some bucks that keeps this event front and center in America. Amazon knows how to tap into what drives today’s shopper.

The following factors all contribute to the feeding frenzy on Prime Day:

A need for stimulation during a slow time of year

The idle mind is the devil’s workshop. The July doldrums are an ideal time to create a prime for online shopping.

An externally sanctioned excuse for consumers to engage in self-gifting

Buying goodies for oneself is a growing trend, but there is still some residual guilt lingering around the idea of self-indulgence. It’s helpful when our culture provides a rationale to throw something in the cart for ourselves while we buy for others. After all, if you’re saving a ton of money on something you might need down the road, you’re actually doing something smart, right?

Purchase momentum

Counterintuitively, in many cases when we satisfy a need we actually want to buy more, rather than taking a breather to enjoy what we already have. Prime Day is an enabler that gives us new things to buy once we have “broken the ice” and started to click for deals.

Exclusivity and group affiliation

Prime Day is, after all, about one thing: Rewarding those who have “seen the light” and joined the Prime family. At this point that includes roughly one-quarter of American households. Amazon uses this incentive to reinforce the relationship with those who are already in the fold, and to entice those who haven’t yet joined the ranks of the anointed. Resistance is futile.

FOMO (fear of missing out), part one

Prime Day is an online phenomenon, and one that has people buzzing (or obsessing) about how to participate. The “meta-hype”—as people like me call it—around the holiday contributes to the torrent of coverage. “How can I miss out?” we wonder. “It’s bad enough that I had to see all those charming photos on Facebook from that party I wasn’t invited to last week.”

FOMO, part two

Injecting an element of uncertainty and implied scarcity into the mix is an old trick—but also an effective one. Because the Prime Day deals come and go rather quickly, the pressure is on to grab every possible bargain. This requires great diligence to be sure you don’t “miss out” on that exact item you didn’t know you craved until you see it heavily discounted.

Amazon gives people good reason to prime their consumption pumps. Other companies can follow the same basic script if they’re able to put their own spin on it: Own or invent a specific time, place, or event that isn’t already taken; stoke the viral fire; inject just enough scarcity and unpredictability into the mix to get that purchase momentum rolling; and sit back and watch as FOMO does the heavy lifting for you.

Michael R. Solomon is a professor of marketing in the Haub School of Business at Saint Joseph’s University and the author of Marketers, Tear Down These Walls!: Liberating the Postmodern Consumer.