In psychology, the biological perspective is a school of thought that focuses on the physical and biological causes of human behavior. The biological perspective of psychology has strong links with some of the biological sciences, in particular neurology and genetics. It is sometimes known as physiological psychology or biopsychology.

The first basic tenet of the biological perspective is that all behavior has a physiological root, and is determined by biology. The second tenet is that a lot of human behavior patterns are based on genetics, because humans have evolved over long periods of time to exhibit behavior that is adapted to the external environment.

Other assumptions in biological perspective relate to methods and scope of study. One assumption is that it is important that psychologists should study the biology behind behavior. This includes the human nervous system and brain, hormonal systems, neurology, and genetics. Another key assumption is that other animals, especially other mammals, can validly be studied in order to help understand human behavior.

A biological perspective on psychology has the important strength of usually being studied using strict scientific methodology. This tends to make the results of this kind of research more reliable than the results obtained using some of other psychological approaches. Practical interventions based on the biological perspective have proven reliable, as for example with many drugs that affect the brain, and certain types of neurological surgical interventions.

Perhaps the most important criticism of this approach to psychology is that it has a strong tendency to reductionism. This means that its theories tend to vastly oversimplify systems that are in reality extremely complex. For example, a biopsychological theory might postulate that a certain hormone causes a behavioral pattern, while the reality might be that such a behavioral pattern is linked to a complex interplay of many different hormones, genetic influences, and multiple environmental triggers. Some researches also criticize the approach because they have doubts that the comparative study of other animals provides information relevant to human behavior.

The biological perspective in psychology has grown tremendously in modern times. This is in large part due to huge advances in the technical methods available to physically study the human brain, such as Magnetic Resonance Imaging (MRI) scans. As scientists gain access to more powerful tools to study the nervous system, they are more able to identify and analyze physical phenomena that may affect human psychology.