Looking for a book about a psychology experiment. Some children were placed in a maze of stairs?

Question

There were 2 or 3 kids in this maze and on platforms between the stairs they would find these little machines that would give them food pellets if they did what it asked. At the end, the kids come out of this maze and when crossing the street, freak at the stoplight that looks like these machines. Any idea what this book was?

Answer 1

Possibly it is "The House of Stairs" : http://www.amazon.com/House-Stairs-William-Sleator/dp/0140345809