Test your vocabulary and help Science!

The scientific goal of this app is to help increase our understanding of one of the most important and complex human skills, our ability to read. Fundamental to this skill is the way we can rapidly and effortlessly decode strings of letters, identifying what word they refer to, and the meaning of that word. To help us in our endeavor, we will use a well-known laboratory task, the lexical decision task.

You will be shown a string of letters that can either form a real word or not. For each string of letters you see, you are asked to decide whether it is a word or not. For a word, press Yes; if not a word, press No.

For each answer, we measure the time it took you to respond (your reaction time) as well as whether you responded correctly or not. This means that we will have for example 100 reaction times and accuracy measures if you respond to 100 letter strings. We also ask for your age category, gender, handedness and your native language. Based on these measures, we are able to perform anonymous statistical analysis and add to existing knowledge about the way we recognize printed words.

The biggest available databases of word reaction times are composed of nearly 40,000 words and 40,000 nonwords, each having 20 to 40 individual reaction times measured with the help of hundreds of participants. This app would be a success if, for each word and nonword, we could acheive 50+ reaction times. This means 40,000 participants responding to 50 words and 50 nonwords (roughly equivalent to a session of 4 minutes). Of course, you can play and send more data. We will be delighted to receive your emails.

The huge number of participants needed here can only be reached with the help of a community of individuals who share the excitement of participating in what might end up being the largest scale investigation ever performed in the history of behavioral science.

If you like it, you can share this app with your friends. Thank you for your cooperation.

What’s New

Version 2.5.1

Science XL 2.5.1:
Better support for GameCenter challenges.
Minor bugfixes & UI improvements.

Science XL 2.5:
Compare yourself to the preliminary Science XL results obtained for English, French and Dutch words experiments!
Game Center integration: check your score on the leaderboards and challenge your friends.
Facebook and Twitter integration to share scores with your friends.
Better profile presentation with session logs and high scores.

Ratings and Reviews

4.0 out of 5
1 Rating

1 Rating


Stephane Dufau
5.8 MB

Requires iOS 5.0 or later. Compatible with iPhone, iPad and iPod touch.


English, Dutch, French, Spanish

Age Rating


  • Game Center

    Challenge friends and check leaderboards and achievements.

  • Family Sharing

    Up to six family members will be able to use this app with Family Sharing enabled.

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