People can't multitask

People can't multitask. Some mind's thought processes differ when people are thinking about the same thing. If he uses his brain to count to himself, he can not talk. However someone may visualize a tape with numbers on it going by and talk. He either can’t count to himself and talk or he can’t watch a metal tape and read. In summary, you can externally and objectively test how a persons brain works by observing what a person can and can’t do while he counts.