Psychology is the science of the human mind and behavior. It evolved from the other sciences, like biology, physics, and sociology. Along the way, it has developed into one of the more socially relevant sciences, with its findings applying to government, business, relationships, sports, and many other topics. But a key challenge for the field is that the mind is less tangible than organisms, matter, or even people themselves. The field also has a replication crisis on its hands, in addition to the skepticism that many people already hold towards the notion of studying the mind scientifically.

But does psychology even have functional theory — a set of cumulative explanations for why something is the way it is? For all the work in psychology, including not only scientific investigations but also applications of psychology to medicine and the law, much psychological research may lack a theoretical foundation. Thinkers going back at least as far back as Thomas Kuhn last century have argued that psychology may not have a unifying rationale, and the theories psychologists do use seem to be poorly defined.

In a paper published in PLOS ONE, a group of scientists studied over 2000 papers published in the leading journal Psychological Science, measuring how often they referred to theory. They found that many studies actually do not use theory, and those studies that do tend to refer to them only once. Just 15.3 percent of the papers specifically aimed to test predictions from theories. 

This means that even a prominent psychology journal dedicated to theory-based science only rarely tests theory. The finding may explain the lack of reliability in psychology, and signals a potential failing in the fundamental scientific enterprise of psychology. Can psychology develop a sound theoretical framework? Perhaps this new focus on the matter will push the field toward that goal.