It's as if every time the brain plans a movement, it has to start from scratch. Practice and training can help improve certain actions, but humans and other primates simply aren't wired for consistency like machines or computers.

"The nervous system was not designed to do the same thing over and over again. The nervous system was designed to be flexible. You typically find yourself doing things you've never done before," study co-author and postdoctoral researcher Mark Churchland said in a prepared statement.