Physiological psychology is the scientific study of the biological factors which underlie human behavior. Various other branches of psychology are primarily concerned with how social, economic, and cultural factors affect human emotions, behaviors, and development. By contrast, physiological psychology focuses on how biological processes—especially those linked to the central nervous system—interact with cognitive, emotional, and other mental processes to shape behavior and personality.
Part of the work of physiological psychologists involves the integration of research from the traditionally disparate fields of biology and behavior to develop a fuller understanding of the interactions and relationships between the two. Researchers in the field also study the biological and neurological underpinnings of such phenomena as sensory processes, emotional behaviors, sleep patterns, sexual conducts, aggressive tendencies, and parental instincts. Interactions between the nervous system and the endocrine system—which secretes hormones— are especially important to their study of such phenomena.
Physiological psychologists often study non-human animal models (including non-human primates), based on the assumption that the species share certain important commonalities and similarities with respect to the linkages between biology and behavior. As such, physiological psychology shares some key theoretical assumptions with fields such as evolutionary psychology, which studies the potential evolutionary roles and implications of psychological traits. Physiological psychology is sometimes referred to as biological psychology, biopsychology, or psychobiology, though some specialists insist that there are certain important distinctions between the subfields bearing these labels.