Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Review of "House of Stairs"

I first read this book back in 1980, and found it to be a very haunting story, yet very thought-provoking. At first, the suspense was wondering how the five captives would escape from the house of stairs, but then it turned to how would they survive by making the machine keep producing food for them. It quickly became apparent that the motives behind the people controlling the food machine were evil, when the machine increasingly would only dispense food when negative behaviors were exhibited, namely the teens fighting with each other. This was at a time when they should most be cooperating with each other to find a way out of the trap. The reader will be horrified to see what the machine could condition people to do, and equally horrified that anybody could use orphans in such a cruel experiment. But it is a stern warning as to how easily people's thoughts and actions can be manipulated.