This paper discusses some concepts of the neurophysiological bases of psychological function and briefly describes an investigation of certain aspects of these concepts. Unlike classical methods of research which involve the isolation of 'single variables in large scale simple systems' or of 'unidentifiable elements in complex microsystems', psychobiological methods involve immense 'complex systems of heterogeneous elements interacting freely with one another through probabilistic links', therefore requiring different approaches. The enormous complexity of the nervous system raises the question whether even our billions of human beings may not be an inadequate sample to permit generalization. Methodological