The Science of Psychology and the Role of CAT, PET, and MRI

From the Lecture Series: Redefining Reality—The Intellectual Implications of Modern Science

By Steven Gimbel, Ph.D., Gettysburg College

The science of psychology had a long and hard way to becoming recognized as a science. The initial psychological theories were based on speculation and guesses since there was no way to prove what the psychologists said. It took a while for psychology to be fully accepted by scientists, and modern imaging techniques had a significant role in this process. Read on to see what psychology owes to imaging technology.

Computer screen showing MRI, CT Image scan of the brain with a team of medical scientists in the background.
The science of psychology was recognized as a science when imaging tools helped psychologists observe the processes in the brain. (Image: Gorodenkoff/Shutterstock)

Traditionally, people used to believe that the human soul was what differentiated humans from the rest of the animals. Reasoning, creativity, and understanding and manipulating the surroundings had to come from a place. When the science of psychology began realizing how these human characteristics work, the traditional attempts turned into a professional embarrassment.

Observable Data in Psychology

The hands of an elderly woman holding the missing white jigsaw puzzle piece from a puzzle shaped like a human head.
Psychologists could not scientifically accept or reject theories as they were all based on speculations and guesses. (Image: Orawan Pattarawimonchai/Shutterstock)

Just like when atoms were an unbelievable theory for the physicians, the first psychological theories were also not easily accepted. There was no way to observe and test either atoms or psychological theories. No scientist could see what was going on in the brain, and no scientist could confirm what the psychologists said.

When Freud talked of unobservable mental structures like the id, the superego, and the unconscious itself, scientists heard some fairy tales. Psychology was at best counted as a soft science, if a science at all. Things changed when CAT scans joined the game.

Learn more about the birth of psychology.

CAT Scans and the Science of Psychology

Psychologists greeted modern neural imaging techniques with wide-open arms. The first type was the computerized axial tomography, commonly known as a CAT or CT scan, which is, in fact, a computer-aided x-ray process. ‘Tomography’ has Greek roots: ‘tom’ means ‘cut’ and ‘graph’ means ‘write’. Psychologists wanted to use it to generate images of slices of the brain.

With CAT scans, scientists could observe the brains of living people. Before that, all the documentation from parts of the brain and the disabilities they caused were prepared and sorted by anatomists. They could only access the brain after somebody’s death. The method was not the easiest, but that was how Paul Broca determined that the region named for him, Broca’s area, was essential to speech.

With the new technology, all earlier psychological claims could be put to the test and accepted or rejected with more than stimulus and response tests. CAT scans changed psychology forever, but nothing is perfect.

This is a transcript from the video series Redefining Reality: The Intellectual Implications of Modern Science. Watch it now, on The Great Courses Plus.

The Problems with CAT Scans

There were two problems with CAT scans. First, x-rays were dangerous to the patients. Second, the CAT scan could only provide snapshots of structure, not action, changes inside the brain, and the actual working of the parts. Just the structural elements could be observed.

Technology advanced further to overcome these shortcomings with two new methods. The first method was magnetic resonance imaging, known as MRI.

Learn more about the caring brain.

Magnetic Resonance Imaging—MRI

MRI was developed by the physicists, but other scientists also welcomed it greatly for medical and psychological research. It is based on the magnetic field that each atom, and the molecule it combines into, generates.

If the molecules are exposed to a strong magnetic field, they will line up in the direction of this magnetic field. When the external field is cut, all the molecules will go back to their previous state. However, the amount of time each molecule needs for going back shows what substances they are made of. MRI was safer and gave the scientists more detailed pictures. However, the problem of having only one snapshot and no action remained. This was where PET scans came to the rescue.

Learn more about the rediscovery of the mind.

PET Scans—Positron Emission Tomography

Profile of bearded man with symbol neurons in brain.
With the help of PET scans, psychologists could see processes inside the brain and detect which part became active during which behavior or thought. (Image: Lia Koltyrina/Shutterstock)

The basis of a PET scan is positron emission, which is the result of radioactivity that can be detected. To do a PET scan, a radioactive form of oxygen attached to a sugar molecule is injected. The substance is taken into the blood and used by cells like normal sugar. Because of the radioactive molecules, every active part in the brain can be detected as they get more blood flow. Now, scientists were looking at a process, not a snapshot anymore.

With PET scans, every human action and element of internal consciousness, like finding something tasty or falling in love, could be observed and studied. Psychologists could finally study the works of Broca and Wernicke from the end of the 19th century in a scientific way.

Common Questions About the Science of Psychology

Q: How was psychology viewed as a science?

It was not viewed as science before imaging technologies could show what went on in the brain. The science of psychology was credited as a science after psychologists could see inside the brain.

Q: How did modern neural imaging techniques help psychology?

Before the imaging technologies, psychology was mere speculation and guesses. The images changed the situation and helped rank the science of psychology as a science.

Q: What is Broca’s area?

It is a region of the brain named after Paul Broca. In the science of psychology, this area is essential for speech.

Q: What was the problem with CAT scans?

CAT scans did help the science of psychology significantly, but x-rays were dangerous to patients, and the CT-scan could only give scientists snapshots of structure. No action, changes inside the brain, or actual working of the parts could be seen.

Keep Reading
The Role of the Environment in Shaping Personality
Self-Awareness and Psychology: Navigating Human Mysteries
Evolution and Psychology: A Mutual Relationship