Why do we have -1 and +1 as binary inputs instead of 0 and 1

Question

I'm trying to get started with neural network and implement boolean functions like AND/OR. Instead of using 0, and 1 as binary inputs, they use -1 and +1. Is there a reason why we cannot use (0, 1)? As an example: http://www.youtube.com/watch?v=Ih5Mr93E-2c

Answer 1

In most cases there's no difference. Just use logistic function activation instead of tanh. In some special forms, e.g., Ising model, it could nontrivially change the parameter space though.