With much of the world turning to digital media, book makers generally aren't in a position to turn down potential readers. But a prototype cover for the Art Director's Club annual in the Netherlands does just that by scanning the face in front of it and, like some kind of literary chasity belt, only opening if it deems the reader to be in a non-judgemental state of mind.
As Wired reported:
To open the book you must align your face within the cover’s robot visage. A camera at the top of the cover captures your facial position, and Nxt software processes the abstracted data to determine your emotional state. If you’re overly expressive (a smile or scowl, for instance) the screen behind the cover will blink red. A neutral facial position will turn the screen green and send an audio signal to an Arduino board that will pop the metal lock open.
And as Biersteker says on the website:
My aim was to create a book cover that is human and approachable-hi-tech. If you approach the book, the face recognition system picks up your face and starts scanning it for signs of “judgement”. If you’re over excited or your face shows a sceptical expression, the book will stay locked. But if your expression is neutral (no judgement) the system will send an audio-pulse to the Arduino and the book will unlock itself. I often worry about my scepticism and judgement getting in my way of amazement. Judgement should never hinder relentless enthusiasm of seeing things for the first time.