Google Android’s 3 UX Design Principles and 2 Jars of Marbles

In their presentation at Google I/O, the designers share their design principles and how they make important UX decisions based on 2 jars of marbles.

Keira Bui


Their UX design key points are divided into 3 categories: Enchant, Simplify and Amaze.


Delight me in surprising ways: A simple animation or a well-timed sound effect can bring joy to the users. Pay attention to these subtle effects because they create a sense of effortlessness for users.

Real objects are more fun than button and menus: Users feel more emotionally satisfied when they can directly touch and manipulate objects in your app (This must sound good to skeuomorphic designers).

Let me make it mine: Everyone wants to add personal touches because it makes them feel in control. Provide defaults, but don’t forget fun, optional customizations.

Get to know me: Learn users’ preferences and avoid asking them for the same feedback over and over. Previous choices should be within easy reach.


Keep it brief: Short phrases and simple words are strongly preferred over technical jargons. People tend to skip long sentences.

Pictures are faster than words: Pictures catch people’s attention and get ideas across more easily than words.

Decide for me but let me have the final say: Guess what the users want and do it rather than asking first. Allowing them to undo your decision is better than asking too many questions.

Only show what I need when I need it: To avoid overwhelming people with too much information at once, hide non-essential options and break tasks into small chunks. Teach people as they go.

I should always know where I am: Places in your app should look different. There should be transitions among screens to show a strong hierarchy. Don’t make the users feel lost.

Never lose my stuff: People should be able to access to their creations, settings, personal touches,… whenever they want. Or they’ll never update your app.

If it looks the same, it should act the same: Help people distinguish different functions by making them look distinct rather than subtle. Don’t use modes, which are places that look alike but act differently on the same input.

Only interrupt me if it’s important: Unless it’s crucial and time-sensitive, don’t bother your users with lots of interruptions.


Give me tricks that work everywhere: Use visual patterns from other Android apps, such as making the swipe gesture as a navigational shortcut. It makes it easier to use your app, and when people figure things out themselves, they feel good!

It’s not my fault: Don’t put the blame on your users and make them feel bad. Be nice when the users forget to insert SIM card or when they reach your 404 page.

Sprinkle encouragement: Break complicated tasks into small chunks and let the users know that their actions took effect, even if it’s just a subtle sound.

Do the heavy lifting for me: Users will feel very grateful if you give them shortcuts that can do more than they expect.

Make important things fast: Key elements in your app should be easy to find and easy to use. They should be more prioritized than others.

According to psychologist Barbara L. Fredrickson, it takes three positive emotions to outweigh every negative one. Based on this, the Google design team set up two jars of marble to examine the costs and benefits. For every positive emotion that the design makes, they put a marble in the good emotion jar. However, if the design causes a negative emotion, they’ll put 3 marbles in the bad emotion jar. Their goal is to get an empty negative jar and a full positive jar.

Two jars of emotion help Google make UX decisions.
It takes three positive emotions to outweigh every negative one.

The team also has a writer that helps them write “positive” messages which don’t place the blame on users. Android’s tone is human-like, friendly and approachable.

Short and simple words are preferred over technical jargons.
One friend is more important than 76 strangers.
Very human-like, conversational tone.
Too much “hello” and “thank you” can be tiring.
Allow users to make final decisions.

Their Ice Cream Sandwich’s UX design principles are also shown in this PDF or on their website.

Overall, I think Google is very smart to share its design process. This is a great way to advertise their products, while making sure it doesn’t look like advertising. Their process exemplifies that even a small decision can cause big changes in user experience, because one negative emotion equals three positive emotion. Of course we shouldn’t stick to these rigid numbers, but still, asking yourself, “What emotion will this design create? Is it positive or negative? How and why?” will help you a lot in UX design.

Let me know what you think. I’m always here on Twitter / Facebook, or you can send me an email via my website.



Keira Bui

Keira is a freelance graphic designer and illustrator. She loves books, ice cream and perfection.