The biological perspective guides psychologists to search for the causes of behavior in genes, the brain, the nervous system, and the endocrine system. The functioning of an organism can be explained from its physiological structure and biochemical processes. Experience and behavior are largely understood as the result of chemical and electrical activity that occurs within and between nerve cells. Researchers with a biological view have generally assumed that psychological and social phenomena can ultimately be understood in terms of biochemical processes: even the most complex phenomena can be understood by being analyzed or reduced to smaller, more specific units. For example, they might use precise biological processes in your brain cells to explain how you read the words in this sentence. This view holds that behavior depends on physiological structures and genetic processes. Experience can alter behavior by altering underlying biological structures and processes. Researchers might ask, "What happened in your brain when you were learning to read?" Psychophysiology researchers are tasked with understanding behavior at the most precise level of analysis.

Researchers adopting a biological perspective have contributed to the development of a cross-cutting field—behavioral neuroscience. Neuroscience studies brain function; behavioral neuroscience attempts to examine the brain mechanisms behind behavior, such as sensation, learning, and emotion. Advances in brain imaging, discussed in Chapter 3, have led to major breakthroughs in cognitive neuroscience. Cognitive neuroscience is an interdisciplinary field of study that focuses on the brain mechanisms underlying higher cognitive functions, such as memory and language. Likewise, brain-imaging techniques allow researchers from a biological perspective to examine a wider range of human experiences.