I recently purchased a book that I've used in conjunction with my psychology classes, called 'Don't Shoot the Dog!: The New Art of Teaching and Training', by Karen Pryor, which is apparently considered a 'classic'.
Much of it naturally seems to be behaviourist theory, which is then extended to human behaviour modification. Are there any other books that people have found useful in terms of extending to helping in more than just training of animals? Or perhaps more 'classics' out there?