Human experimental psychologists are in a most curious position. Their subject — the human brain — is obviously the most complicated thing studied by any science. Its components (neurons) are not only very numerous and densely-connected they are also very inaccessible. Moreover brains soak up their environments in a way that other objects of study do not. It isn’t impossible to do experiments, but it isn’t easy. You can’t keep a supply of humans in your lab, for example. The difficulty of human experimental psychology is the main reason I decided to study animal experimental psychology. But the complexity of the brain is