For starters, every interaction a person has with a digital product follows the same pattern: Information — User filters the information Significance — User looks for its meaning Time — User takes an action within a time frame Memory — User stores fragments of the interaction in their memory For each of these stages of interaction, I’ve compiled a list of the most relevant design principles and cognitive biases that will help you to build habit-forming products.

You may be wondering: If users want personalization, then what’s the problem? The problem is that personalization is a bit like walking a tightrope. A very thin line separates the “good” kind of personalization from the creepy kind. “I like it because it’s so similar to me” can easily become “I don’t like it because it’s eerily similar to me.” “This is relevant to me and saves me time and effort” can easily become “The algorithm is stereotyping me and that’s not cool.” This switch from good to bad is where user psychology comes in. Understanding the real reason why personalization works can help us understand why it does not work sometimes.