Indeed, research finds that quantity purchase limits increase sales by more than 50 percent.

As we discussed, one key factor is how frequently the stimulus occurs. Hot chocolate would also have fitted really well with Kit Kat, and the sweet beverage might have even complemented the chocolate bar’s flavor better than coffee. But coffee is a more effective trigger because people think about and see it much more frequently.

The desire for social approval is a fundamental human motivation.

The key to finding inner remarkability is to think about what makes something interesting, surprising, or novel.

SAVING A COUPLE OF BUCKS

Principle 2: Triggers

Marketing is about tapping into their genuine enthusiasm for products and services that they find useful. Or fun. Or beautiful. Marketing is about spreading the love.

EXERCISE MAKES PEOPLE SHARE

Introduction: Why Things Catch On