Book review: “Hooked: how to build habit-forming products”

What makes a product or service really stick in your mind? Do you have an app on your phone that you always turn to whenever you’re bored? If you’ve got a problem to solve, is there a specific product or service you tend to use to look for a solution? American journalist and lecturer Nir Eyal has written a book about how to best create ‘habit-forming’ products, creating ways for users to get ‘hooked’. In “Hooked: how to build habit-forming products” Nir focuses on those elements that make up the “Hook Model” and which help to create products which become an integral part of our lives.

What I liked best about reading “Hooked” are the insights that it provides around the user journey that product people can design and optimise for; not just designing for a one-off experience but creating a lasting engagement with the user. Nir illustrates this form of lasting engagement through the so-called “Habit Zone” which plots ‘frequency’ against ‘perceived utility’ (see Fig. 1 below). Let’s start this review by looking at the four elements of the Hook Model: Trigger, Action, Variable Reward and Investment (also see Fig. 2 below):

  1. Trigger  Nir describes a trigger as “the actuator of behaviour – the spark plug in the engine.” There are two forms of triggers: external and internal triggers. Habit-forming products use external triggers such as as an email or a website link to alert users. These are all external alerts. The point that Nir makes is that when users start to automatically cue their next behaviour, the new habit becomes part of their everyday routine. In other words: as soon as users no longer need an external alert, a habit – powered internally – has been formed.
  2. Action – A trigger is pretty useless if it isn’t followed by an action. Nir explains that “to initiate action, doing must be easier than thinking” and refers to the “Fogg Behaviour Model” in this respect (see Fig. 4 below). This model shows that behaviour will occur when motivation, ability, and a trigger occur at same time and in sufficient measures. I found it particularly interesting to read about ‘ability’ and BJ Fogg’s six “elements of simplicity”, which represent the factors that influence the difficulty of a specific action (see Fig. 5 below). This focus on making actions as easy as possible is one of the key reasons why companies are moving towards ‘single purpose’ apps and are constantly looking to reduce the number of steps that users have to go through (I wrote about single purpose apps a few weeks ago). Nir also asks the question around where to start: motivation or ability? His answer is very clear: always start with ability. Nir’s point here is that “for most companies building technology solutions, the greatest return on investment will generally come from increasing a product’s ease-of-use.”
  3. Variable Reward – The word that intrigued me most with regard to this third element of the Hook model was “variable”. In the book, Nir explains that when users are (pleasantly) surprised by a new reward, this is likely to have an impact on their usage of the product or service. Three different types of variable rewards are further explained in the book: the “Tribe”, the “Hunt” and the “Self” (see Fig. 6 below). Habit-forming products tend to use one or more of these variable reward types in order to keep users excited and engaged.
  4. Investment – The fourth and final element of the Hook model is “investment” This is about getting users to invest, to put effort into a product. Nir talks about a psychological phenomenon known as the “escalation of commitment” whereby people are driven to keep on investing into a product or service. It’s a phenomenon often encountered in video games, where players go through countless levels of a game. Twitch is a great example of a successful community built around some of these characteristics. The key point here is that the more users invest time and effort into a product or service, the more they value it. Nir talks about “storing value” in this regard; the stored value users put into the product increases the likelihood they will use it again in the future and comes in a variety of forms (see Fig. 7 below).

In Chapter 6 of the book, Nir provides a nice overview of the five fundamental questions for building fundamental hooks (see Fig. 8 below). He goes on to explain that the Hook Model is fundamentally about changing people’s behaviours; but the power to build persuasive products should be used with caution. He acknowledges that the Hook Model and subsequent persuasive products can be abused by product people and introduces the “Manipulation Matrix” in this regard (see Fig. 9 below).

There were a few more key things which I took away from reading “Hooked: how to build habit forming products”:

  1. Avoid manipulation – As a product person, the role of a “Facilitator” is the one that you want to play; creating a product that you would use and that you believe will make the user’s life better. In effect, you’re facilitating a healthy habit. I guess that’s exactly the main concern that I have with some product people and their application of some of the insights and examples in “Hooked”. I hear people talking about ‘tricks’ and ‘mechanisms’ and I worry sometimes that the underlying user need gets overlooked or downplayed. It’s one of the reasons why I believe that product people should always take the Internal Trigger as a key reference point when creating and evaluating a product or a service.
  2. Habit Testing – Inspired by the build-measure-learn approach of the “Lean Startup” movement, Nir introduces the continual process of “Habit Testing” which can help offer insights and actionable data to inform the design of habit-forming products. The practical steps that Nir outlines with regard to Habit Testing are very useful and can easily be integrated in one’s more standard user testing processes (see Fig. 10 below).

Main learning point: In “Hooked: how to build habit-forming products” Nir Eyal provides a very useful lens for anyone involved in product development. User habits are pivotal and the “Habit Zone” is where most products and services will want to be. The aspects of the Hook Model which I found most helpful are Trigger and Action as both got me to think more about what drives users and how to best translate this motivation into action. If you are interested in learning more about how user habits are formed and how products can tap into this, then “Hooked” is a must-read!


Fig. 1 – The Habit Zone by Nir Eyal (taken from: habit-zone2

Fig. 2 – The Hook Model by Nir Eyal (taken from: Hook Model

Fig. 3 – Types of external and internal triggers (taken from: “Hooked: how to create habit-forming products” by Nir Eyal, Chapter 2):

External triggers:

  1. Paid Triggers – Advertising, search engine marketing, and other paid channels are commonly used to get users’ attention and prompt them to act.
  2. Earned Triggers – Earned triggers are free in that they can not be bought directly, but they often require investment in the form of time spent on public and media relations.
  3. Relationship Triggers – One person telling others about a product or a service can be a highly effective external trigger for action.
  4. Owned Triggers – Owned triggers consume a piece of real-estate in the user’s environment. They consistently show up in daily life and it is ultimately up to the user to opt into allowing these triggers to appear. Owned triggers are only set after users sign up for an account, submit their email address, install an app, opt into newsletters, or otherwise indicate that they want to continue receiving communications.

Internal Triggers: 

  1. Emotional Triggers – Emotions, particularly negative ones, are powerful internal triggers and greatly influence our daily routines. Feelings of boredom, loneliness, frustration, confusion and indecisiveness often instigate a  slight pain or irritation and prompt an almost instantaneous and mindless action to quell the negative sensation. Positive emotions can also serve as internal triggers, and may even be triggered themselves by a need to satisfy something that is bothering us.


Fig. 4 – BJ Fogg’s Behaviour Model (taken from: Behavior Model

Fig. 5 – BJ Fogg’s six “elements of simplicity” (taken from: “Hooked: how to create habit-forming products” by Nir Eyal, Chapter 3)

  • Time – How long it takes to complete an action.
  • Money – The fiscal cost of taking an action.
  • Physical Effort – The amount of labour involved in taking the action.
  • Brain Cycles  The level of mental effort and focus required to take an action.
  • Social Deviance – How accepted the behaviour is by others.
  • Non-Routine – How much the action matches or disrupts existing routines.


Fig. 6 – Three Variable Reward Types (taken from: “Hooked: how to create habit-forming products” by Nir Eyal, Chapter 4)

  • Rewards of the Tribe – Rewards which are based on the way in which our brains are adapted to seek rewards that make us feel accepted, attractive, important, and included. Examples of such rewards can be found in sites such as Quora and Stack Overflow.
  • Rewards of the Hunt – This reward type is very much about the ‘chase’; the pleasure we can derive from the pursuit itself. A good example is Pinterest where users never know what they will find on the site. To keep users searching and scrolling, some of the pictures on Pinterest seem to be cut off. However, the idea is for these images to ‘tease’ the user and to offer them a glimpse of what’s ahead.
  • Rewards of the Self – This third and final variable reward type has to do with a more personal form of gratification. Nir mentions a good example in video games, where players seek to master the skills needed to pursue their quest. A good example can be found in Twitch which has built a great community around some of these characteristics.


Fig. 7 – Types of investment, storing value into products or services (taken from: “Hooked: how to create habit-forming products” by Nir Eyal, Chapter 5)

  • Content – Examples of sites where users store value by adding content are Spotify (where users create, store and share music playlists) and photo-sharing site Flickr. Similarly, users can store value through content in the form of “likes” or videos shared on Facebook.
  • Data – Users can store value in a product or service by adding data about themselves or their behaviours. Good examples are LinkedIn (where people store their CVs and keep details of their business contacts) and Tripit (where people create and store their travel itineraries).
  • Followers – Apart from the gratification that people can get from having a large number of followers on social media such as Twitter and Quora, Nir argues that the more followers one has, the more valuable the service becomes to the user as a result.
  • Reputation – Reputation as a form of stored value comes in all kinds of different shapes and sizes. Nir mentions online marketplaces such as eBay and Airbnb where people with negative scores are treated very differently from those with good reputations.
  • Skill – Investing time and effort into learning to use a product is a form of investment and stored value. Once a user has acquired a skill, the service becomes easier and moves users to the right on the ability Axis of the Fogg Behaviour Model (see Fig. 4 above). A good example is the well known graphics editing programme Adobe Photoshop which enables users to pick from a wide range of features, varying from basic to very advanced.


Fig. 8 – Five fundamental questions for building effective hooks (taken from: “Hooked: how to create habit-forming products” by Nir Eyal, Chapter 6)

  1. What do users really want? What pain is your product relieving? (Internal Trigger)
  2. What brings users to your service? (External Trigger)
  3. What is the simplest action users take in anticipation of reward, and how can you simplify your product to make this action easier? (Action)
  4. Are users fulfilled by the reward, yet left wanting more? (Variable Reward)
  5. What “bit of work” do users invest in your product? Does it load the next trigger and store value to improve the product with use? (Investment)


Fig. 9 – Manipulation Matrix (taken from:


Fig. 10 – Steps involved in Habit Testing (taken from: “Hooked: how to create habit-forming products” by Nir Eyal, Chapter 8 and

  • Step 1: Identify – Define what it means to be a devoted user. How often “should” one use your product?
  • Step 2: Codify – Codify the steps that your users took using your product to understand what hooked them. You’re looking for a “Habit Path”; a series of similar actions shared by your most loyal users.
  • Step 3: Modify – Armed with new insights, it’s time to revisit your product and identify ways to nudge new users down the same Habit Path as taken by devotees.

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Related links for further learning:






What to expect from iOS 8?

Last week, Apple spent a large part of its keynote at WWDC 2014 talking about iOS 8, its new operating system for its handheld devices. These are the main features that we can look forward to as part of iOS 8:

  1. Touch ID – Apple’s “Touch ID” fingerprint recognition system is currently only available on iPhone 5S but will now be integrated into iOS 8 and will become available on more Apple devices. Instead of having to remember lots of different passwords, with Touch ID users will now be able to complete transactions just using their fingerprints (see screenshot in Fig. 1 below). In addition, with iOS 8 there is a likelihood that users will be able to scan credit cards via an iPhone or iPad camera and automatically fill in their details as part of an online shopping transaction.
  2. Handoff – With Apple’s “Handoff”, users will be able to switch seamlessly between devices; one can start watching something on an iPhone and then continue watching on an iPad, without any overlap or lag (see Fig. 2 below). Another important aspect of Handoff is the inclusion of the Mac, Apple’s desktop, and the notion that the desktop operating system can now talk to an Apple mobile operating system without any friction. For example, it means that when you start working on a document on a desktop, you can easily resume working on the document on your mobile, without having to delve into different folders, etc.
  3. Interactive Notifications – iOS 8 will include new interactive notifications which will allow users to reply to text messages or accept calendar invites without leaving the app that they are in. These new interactive notifications can be invoked from their temporary banner that appears at the top, as well as on the lock screen (see Fig. 3 below).
  4. Health – At last week’s WWDC, Apple presented it’s new Health app and a developer focused Healthkit API. The Health app effectively aggregates all your health and fitness data, irrespective of the apps that you use to generate this data. Examples of popular fitness/health apps are Fitbit are FitStar and their data can be aggregated into a secure dashboard on your Apple smartphone or tablet (see Fig. 4 below). With the Healthkit API, developers can start integrating the data of health/fitness apps with Apple’s Health app.
  5. HomeKit – With the “Homekit”, Apple is taking a firm leaf out of Nest‘s book. Nest is all about creating a connected home and which home products are designed to learn from user behaviour (I wrote about Nest earlier in the year). The technology which underpins Apple’s HomeKit is very complex, but in essence it covers one or more ‘Homes’, with different ‘Rooms’ within the Home. For example, you can have a room called “Master Bathroom” in your Home and you can have two distinct actions which you can trigger through Siri, Apple’s voice command technology: (1) closing the bathroom door and (2) turning on/off the bathroom light.

Main learning point: Apple has introduced some interesting features as part of it’s new iOS 8 operating system for its handheld devices. Perhaps the least sexy one out off all these features, but the “Handoff” connectivity feature is a really critical one as it will enable users to seamlessly switch between Apple devices and desktop. If I were to go for ‘sexy’, then Apple’s forthcoming Health app is probably the most exciting, both from a user perspective and from a data aggregation perspective.

Fig. 1 – Screenshot of Touch ID integration into Mint app (taken from:


Fig. 2 – Apple’s Craig Federighi presents Apple Continuity for Mac OS at WWDC ’14 on 2 June ’14 (taken from: CNET News,

Fig. 3 – Screenshot of Apple’s Interactive Notifications (taken from:


Fig. 4 – Screenshot of the dashboard function of Apple’s Health app (taken from:


Related links for further learning:


Why ‘single purpose’ apps are en vogue

As I’m currently investigating how to best simplify the ways in which user discover new content – as part of my day job as a product manager at Beamly – I have been thinking more about so-called ‘simple purpose apps’.

The words ‘single purpose’ indicate that the apps focus on a singular user ‘job’ (I’ve written about ‘jobs’ previously). For example, Facebook’s “Paper” which concentrates solely on one job; enabling users to upload and share stories. It’s almost like we’re decomposing multi-purpose apps and recreating them into smaller, single task oriented apps.

I’ve thought about this a bit more and looked at some recent examples:

  1. Why single-purpose? – The other day, I heard about a quote from Foursquare CEO Dennis Crowley, whose company has just split its app into two: “Swarm” (for keeping up and meeting up with friends”) and “Foursquare” (local search personalised to a user’s tastes). “What we’re starting to see is that the best apps tend to be the simplest, the easiest to use and the fastest to use” Dennis Crowley told the Guardian. “I think there’s a larger trend towards unbundling apps and making very easy, simple, clean and elegant single purpose use case apps, and I think that’s what we’re doing.”
  2. What do users want? – In my ongoing conversations with users, it always dawns on me how much people seem to value simplicity and/or ‘structure’ in products. Whether it’s a physical product or a digital application, my perception is that people like to know exactly what a product is for and what it doesn’t do. Users don’t like getting confused by tasks which aren’t core to the key reason for wanting to use the product in the first place. I really like the “Laws Of Simplicity” by John Maeda (see Fig. 1 below). I believe that the current move towards single purpose apps ticks at least four of John Maeda’s Laws Of Simplicity: Context, Time, Organize and Reduce.
  3. Other benefits of ‘unbundling’ – I learned a lot from Taylor Davidson’s views on the benefits of unbundling and him taking Facebook’s current strategy as an example. Taylor points out a number of valid touch interface reasons which accommodate single support apps (as outlined in Fig. 2 below). Touch interfaces make it easy to surface and access multiple apps, and the data capture of specialised apps. Taylor also highlights some constraints and risks to consider in relation to single purpose apps (see Fig. 3 below). Both risks that Taylor points out – lots of single-purpose apps competing for user attention and capturing data in isolation – make a lot of sense and need to be taken seriously.
  4. Facebook’s ‘social conglomerate’ strategy – Rather than creating one product or app which does everything, Facebook seems to be following a so-called ‘social conglomerate strategy’ whereby it makes targeted acquisitions to include specific services in its portfolio (and which continue to exist under their own brand name and within their own ‘home’). Good examples are Facebook’s acquisition of WhatsApp and Oculus Rift. As Taylor Davidson explains in his aformentioned blog post; having a social conglomerate strategy in place enables the likes of Facebook, Dropbox and Foursquare to use different brands and applications “to reach difference use cases, demographics, and desires.”

Main learning point: The unbundling of apps seems like a very logical trend, with companies such as Facebook and Dropbox looking to both simplify their apps and to address different use cases / audiences through separate apps or brands. It will be interesting to see how recently acquired single purpose apps such as WhatsApp will be integrated within the Facebook ‘conglomerate’ and whether there will be cases where the single purpose app strategy backfires due to a plentitude of apps available to users.

Fig. 1 – The Laws Of Simplicity by John Maeda (taken from:

  • Law 10 – The One: Simplicity is about subtracting the obvious, and adding the meaningful.
  • Law 9 – Failure: Some things can never be made simple.
  • Law 8 – Trust: In simplicity we trust.
  • Law 7 – Emotion: More emotions are better than less.
  • Law 6 – Context: What lies in the periphery of simplicity is definitely not peripheral.
  • Law 5 – Differences: Simplicity and complexity need each other.
  • Law 4 – Learn: Knowledge makes everything simpler.
  • Law 3 – Time: Savings in time feel like simplicity.
  • Law 2 – Organize: Organization makes a system of many appear fewer.
  • Law 1 – Reduce: The simplest way to achieve simplicity is through thoughtful reduction.

Fig. 2 – Benefits of ‘unbundling’ (taken from:

  • The touch interface of mobile smartphone operating systems makes it easy to survey multiple applications to select from: easier than opening up a single app to dig through a menu and list of features.
  • Mobile operating systems unlock a data platform for specialized mobile apps to leverage in a way that isn’t possible on the desktop today.
  • Contacts, calendar, photos, location, storage, and more are all available for an app to access with ease, and that accessibility makes it easy to build a valuable specialized application on top of mobile platforms.

Fig. 3 – Risks to consider in relation to ‘unbundling’ (taken from:

  • The problems of customer acquisition and engagement are magnified. In a world where customer acquisition and engagement on mobile are major challenges (read a million other articles about the problems of app store discovery and search, download metrics and tracking, and more), the proliferation of single-purpose apps increases the competition for homescreen and top-of-mind share.
  • Single-purpose apps amplify the amount of siloed data and reduce the data scale held by any one app. Single-purpose apps build deep understanding about interactions about our actions and behaviors in very specific ways (i.e. what we read, what we listen to, how much we work out, where we go), which makes them very powerful sources of data, but also locks that data away from other apps.

Related links for further learning:



Twitch and its appeal for Google and Microsoft

The other day, I heard about the rumoured takeover of Twitch by Google for the handsome amount of $1 billion. I have to be honest; up until that point I had never heard about Twitch. Reason enough to look into Twitch and a possible ratio for Google willing to spend such a large amount of cash on this startup:

  1. What is Twitch? – Twitch is a video streaming platform and a community for gamers. Geekwire describes Twitch as “the ESPN of the video game industry” and says Twitch is a leader in that space. Twitch has over 45 million monthly users and about 1 million members who upload videos each month. In a relatively short space of time (Twitch was launched in June 2011), Twitch has successfully created an online streaming platform for video games.
  2. Who use Twitch? – I’m not an avid video gamer myself, but browsing the Twitch website tells me that are in effect two main user roles, which are closely intertwined: game players and broadcasters. Clearly, you can be both and I’m sure that a lot of Twitch members fulfil both roles. One can play games on Twitch channels like Counter-Strike: Global Offensive or World of Tanks or one can create their own pages from which you can broadcast games. A great example of Twitch’s success in engaging its community around a game is TwitchPlaysPokemon which has had over 78,000 people playing a game that turns chat comments into controller inputs, parsing hundreds of thousands of ups, downs, and starts and translating them into in-game movements.
  3. Why is Twitch such an interesting acquisition target? – Twitch is reported to have snubbed Microsoft’s takeover offer but is rumoured to have fallen for Google. This raises the question as to what makes Twitch such an interesting takeover target? I think that the answer can be split into two main factors. Firstly, scale. Twitch has a rapidly growing and very engaged user community who all share a passion for (video) gaming. Secondly, live broadcasting. Going back to the example of TwitchPlaysPokemon, Twitch streams games that get people excited and gets them participating in real-time. This simultaneous element is something that for instance YouTube is lacking. YouTube is great for on-demand video content, but (currently) less so for live event coverage or participation. The combination of both factors (as well as a very rich vein of user generated content and data) makes Twitch an extremely interesting target indeed.

Main learning point: Recently there have been some major takeover deals in the digital industry – think Instagram, WhatsApp and Beats – but the rumoured acquisition of Twitch by Google is interesting for a number of reasons. If I have to highlight one key reason, then synergy is the main aspect that makes this potential takeover sound like a very exciting one. How will Google potentially integrate YouTube and Twitch or at least find a way to combine both platforms? Will the acquisition of Twitch help YouTube in cracking the real-time broadcast element of its offering? Lets wait and see if the deal actually gets done in the first place, but if it does then I will definitely keep an eye out for any future developments involving Google, YouTube and Twitch.

Related links for further learning: