Behavioral effects
Biases from behavioral research that change what people pick, pay and come back for: how a price is framed, what is preselected, what feels scarce or half finished.
18 behavioral effects most used in the teardowns first
Default effect
People tend to stick with whatever option is preselected, so the default often decides the outcome for most users.
Anchoring
The first number or option people see becomes a reference point that pulls later judgments of price and value toward it.
Social proof
People look to what others like them do or choose when deciding what to do themselves, especially when unsure.
Goal-gradient effect
People put in more effort the closer they feel to finishing, so visible progress toward a near goal speeds them up.
Aesthetic-usability effect
People judge attractive, polished interfaces as easier to use and more credible, and forgive them small problems.
Framing
The same facts lead to different choices depending on how they are described, for example as gains or losses.
Loss aversion
A loss tends to feel bigger than a gain of the same size, so framing what users stand to lose can motivate action.
Reason-giving
People are more willing to agree to a request when it comes with a short reason that says why it is asked.
Reciprocity
When someone gives us something first, we feel inclined to give something back.
Urgency
A real deadline gives people a reason to act now instead of putting off a decision they already intend to make.
Endowed progress effect
People work harder to finish a goal when they are given a head start, even if the head start is artificial.
Habit formation
Repeating an action in the same context, with a cue and a reward, gradually makes it automatic so people return without deciding to.
Scarcity
Things seem more valuable when they are limited or running out, which makes real limits and quotas strong prompts to act.
Choice overload
Too many options, or options that look alike, can make people delay, choose badly or not choose at all.
Decoy effect
Adding an option that is clearly worse than one of the others makes that other option look better and more likely to be chosen.
Endowment effect
People value something more once they own it or have put work into it, so giving it up feels costly.
Labor illusion
People value a result more when they can see the work that went into producing it, even if it takes longer.
Zeigarnik effect
Unfinished tasks tend to stay on people's minds and pull them back, so a visible "you started this" prompt can bring users back.