Behavioural design

Habit mapping and hijacking

The habit loop

The classic model of habitual behaviour is shown below. 

The habit loop used by Charles Duhigg in his book, 'The Power of Habit'.

The habit loop used by Charles Duhigg in his book, 'The Power of Habit'.

Another common way of expressing the habit loop

Another common way of expressing the habit loop

Nir Eyal taught at the Stanford Persuasive Technology Lab, alongside BJ Fogg. He has specialised in habit formation, and has published a book on this topic, called 'Hooked'. We have a couple of copies around the office. 

Eyal built on the classical habit model to add in a fourth step: investment. Investment is any action users take that increase future engagement with a product.

For instance, the investment phase for someone who has just started using Pinterest (or Flipboard, Pocket, etc) would be installing a browser bookmarklet. This bookmarklet makes them more likely to clip/save content, so they'll be more motivated to return to the app/website.

This slide deck (from a blog post on Eyal's website) explains the psychological basis for the investment phase.


There are two kinds of triggers: internal and external. When people think about triggers, they often focus on the external, but internal triggers can be much more compelling and hard to resist.

Internal triggers

  • Feeling bored
  • Feeling hungry
  • Feeling lonely

External triggers

  • SMS
  • Email
  • Alarm bell
  • App notification
  • day-to-day events, eg getting out of bed, putting on shoes, picking up keys

An exercise to generate trigger ideas

Ask everyone to come up with triggers in each of the following categories - OR using an adapted empathy map template.

  • Think
  • Feel
  • See
  • Hear
  • Smell
  • Taste (may not be relevant!)
  • Touch (may not be relevant!)


Eyal's other significant contribution to habit theory was his taxonomy of rewards. Typically, when considering incentivising behaviour, people think about money or glory. From this springs all the stupid gamification/badges/etc.

Eyal suggests there are three types of reward that could be used:

Rewards of the hunt: these are the classic type of reward/incentive: money, rare knowledge or rare objects.

Rewards of the tribe: these are social rewards, such as acceptance or inclusion in a group, respect from others, and importance or attractiveness in the eyes of others.

Rewards of the self: these are more inward focused, and often rely on cognitive bias. They include mastery (levelling up in some ability that matters to the user), consistency (we need to feel like we behave consistently, and that our behaviour matches our sense of self) or completion (leaving things unfinished niggles away at us)

If you'd like to discourage certain behaviour, then just reverse these rewards: make people feel social rejected, or make them lose money or damage their sense of self.

Variable rewards are more effective. For reasons psychologists are still arguing about, getting a different amount of reward each time, or sometimes getting no reward at all, makes habits stickier than if you get exactly the same reward every time.

Be careful when using rewards/incentives

A large body of research shows that rewarding or punishing people can be ineffective at best, or backfire at worst. For the full story, read 'Punished by Rewards', but here are some key insights:

  • Incentives only work for as long as they're given. If you incentivise people to do something which offers no value to them, even over time, and then stop giving them incentives, they will stop doing whatever it is. Same applies for punishments.
  • If you incentivise people to do something that is intrinsically rewarding in some way, they will usually stop seeing it as being rewarding. When you bribe children to eat vegetables, they grow up thinking vegetables aren't tasty.
  • People feel manipulated by rewards and often resent them as much as punishments.

Using habit theory in design practice

Mapping habits

Make a experience map, or another diagram of a user journey. It's better for this exercise if the journey is longer. For a project looking at online grocery shopping, for instance, we made one that tracked all the food shopping activities between the previous online grocery order arriving, and the next one. Leave a horizontal band for adding in habit info.

Identify what kind of decision making mode the user is in at different phases of the journey: habitual/automatic or conscious/considered. 

In the habitual phases, try to nail down exactly what is the trigger, action and reward. It can help to get people to work in pairs to do this, as it can be tricky to grasp at first. You can use these worksheets to prompt people, but also to stick up on the journey diagram/experience map.

Hijacking habits

Once you've identified existing habits, you can start to think about how they can be changed. It's often easier to hijack an existing habit than create a new one.

There are two ways to hijack a habit:

  1. Build on top of it
  2. Overwrite it: use the same trigger, but change the action and/or reward

Building on top of habits

Building on top of habits can be a really effective way to add new habitual behaviour. You use the entire existing habit as a trigger for the new habit. However you need to start so, so small with the action in your new habit. For instance, one of the examples BJ Fogg gives in his free programme called Tiny Habits is: when you've finished brushing your teeth, you floss one tooth. 

Once the habit's ingrained, you can make the action gradually more and more demanding. But starting small is the key to making it stick.

Overwriting habits

Overwriting habits is harder, as it requires a deeper engagement with the theory of habit formation, and with Fogg's Behavioural Model.

Start by making sure you understand your existing habit: in particular, make sure you know all of the triggers and all of the rewards. There are often internal and external triggers, and/or multiple different rewards. These will help suggest what the new habit could or should be – or at least the parameters that will define it.

Now generate ideas to start to shift the trigger, ability and motivation of the existing habit:

Trigger: can you remove the trigger entirely? can you make it occur less often? can you make it less compelling when it occurs? (eg: you check Facebook when you're bored at work, so turn your phone off while you're trying to focus, and the notifications won't trigger you to check FB)

Ability: can you make it harder to do the existing action? or harder to do the existing action than the new action you want to encourage? (eg: you check Facebook when you're bored at work, so turn your phone off to make it harder to check FB)

Motivation: can you remove or diminish the reward? can you replace it with a punishment?


Hooked, by Nir Eyal

The Power of Habit, by Charles Duhigg

Punished by Rewards, by Alfie Kohn

Worksheets for habit mapping & hijacking: PDF, editable InDesign file