Feedback loops are all around us, but predictable ones don’t create desire. The unsurprising response of your fridge light turning on when you open the door doesn’t drive you to keep opening it again and again. However, add some variability to the mix — say a different treat magically appears in your fridge every time you open it — and voila,

The investment phase increases the odds that the user will make another pass through the hook cycle in the future. The investment occurs when the user puts something into the product of service such as time, data, effort, social capital, or money.

and Berkshire Hathaway CEO Warren Buffett once said, “You can determine the strength of a business over time by the amount of agony

Gourville claims that for new entrants to stand a chance, they can’t just be better, they must be nine times better. Why such a high bar? Because old habits die hard and new products or services need to offer dramatic improvements to shake users out of old routines. Gourville writes that products that require a high degree of behavior change are

longer good enough. Companies increasingly find that their economic value is a function of the strength of the habits they create. In order to win the

useful and rewarding the behavior is in the user’s mind over alternative solutions).

As we will learn in chapter five, users also increase their dependency on habit-forming products by storing value in them

but there are other things that catch her eye as well. The exciting juxtaposition of relevant and irrelevant, tantalizing and plain, beautiful and common, sets her brain’s dopamine system aflutter with the promise of reward.

explores why some people eventually lose their taste for certain experiences and how variability impacts their retention.