Much of psychology is concerned with how we think and behave—the ways that our minds work. But the activity of our minds takes place physically in our brains. In the 20th century, a branch of psychology developed that looks at the connection between the biology of our brains and our behavior.

Philosophical minds

Until the development of neuroscience, most people thought of the mind as something separate from the body. This idea originated with the Ancient Greek philosophers, and persisted, even with the advent of science and medicine, in the writings of 17th-century philosopher René Descartes. These philosophers believed that the mind is a kind of “soul,” which is capable of thought, while the brain is purely physical and exists to receive information from the senses. Little was known about the physical workings of our brains when psychology first emerged as a science, and many of the early psychologists came from a background of philosophy. As a result, psychology existed for a long time only as the science of the mind and behavior, completely separate from neuroscience—the biological study of the brain.

Mind over matter

Even today, some psychologists believe that the physical makeup of our brains is largely irrelevant to understanding thoughts and behavior, and that any explanation can be provided in terms of our minds. One proponent of this view is the American cognitive scientist Jerry Fodor. In the 1980s, he suggested that the mind is made up of many different parts, or “modules,” each with its own function—such as retrieving memories or articulating speech. The idea was not entirely new: A century earlier, a pseudoscience called phrenology divided the mind into 27 specialized modules, each associated with an area of the brain. In Fodor’s modular theory, however, the mental faculties are not associated with specific parts of the brain, and the modules exist independently from the biological structure of the brain.

Phrenologists claimed to be able to measure intelligence and personality by the size of the bumps on a person’s head.

Brainpower

Advances in neuroscience allowed scientists to study the structures of the nervous system, and also observe what happens when different parts of the brain are damaged. As a result, certain areas became associated with particular mental faculties. Biological psychology—the “brain approach,” as opposed to the “mind approach”—gradually emerged to examine the relationship between the physical workings of our brains and our behavior. Sophisticated scanning technology has also allowed us to observe and measure brain activity: For example, electroencephalography (EEG) detects electrical signals, and functional magnetic resonance imaging (fMRI) measures blood flow in different parts of the brain. These techniques have enabled neuroscientists and psychologists to observe which areas of the brain are associated with different behaviors. However, they have also revealed that our brain activity is more complex than previously thought, and that the functions of our minds do not correspond so simply to specific areas of the brain. Certain patterns of brain activity can be associated with different mental states, challenging the idea that the mind is a completely separate entity. Even so, the “brain approach” has not yet provided anything like a full explanation of why we behave the way we do.

SEDUCTIVE SCANS

A study in 2008 by Deena Weisberg showed that nonscientists are more likely to believe even bad explanations of psychological phenomena if they are accompanied by neuroscientific information and fMRI images. These findings have fueled concerns about presenting neuroscientific evidence to juries in criminal trials.

While you are awake, your brain generates enough energy to power a light bulb.