We all have at least a few Type A people in our lives, and we might have even butted heads with one or two of them. The highly competitive, angry, impatient, perfectionist sort of person who strives to be the best at everything is a familiar type, whether you consider them models of success or workaholics with tunnel vision.

"I tell my students, they call it Type A, not Type B, for a reason," Susan Whitbourne, a psychologist based at the University of Massachusetts Amherst, tells Mental Floss. "You want to be Type A-plus, if you're Type A."

The phrase Type A wasn't just born out of the ether: It was created as a way to identify people with certain patterns of behavior prevalent among those with coronary heart disease. In the 1950s, a pair of American cardiologists, Meyer Friedman and Ray Rosenman, were sharing an office in San Francisco when an upholsterer repairing their waiting-room furniture made an odd remark. He was surprised by the wear pattern on their chairs, he said, in which only the front edges of the seats were worn, rather than the back. Patients were literally waiting on the edges of their seats for their name to be called—rather than reclining comfortably toward the back.

At first the pair were too busy to take much note of the upholsterer's comments. But in the mid-1950s, they began looking at the literature around coronary heart disease and wondering if something other than diet (then painted as the most significant culprit) might be playing a part. In a 1956 study of San Francisco Junior League members, they found that diet and smoking didn't seem like adequate explanations for the different rates of heart disease they were seeing in women and men, since husbands and wives tended to share the same food and smoking habits. Female hormones were dismissed as a factor, since black women were suffering just as much heart disease as their husbands. They discussed the issue with the president of the Junior League, who responded, "If you really want to know what is going to give our husbands heart attacks, I'll tell you … It's stress."

That's when Friedman and Rosenman remembered the upholsterer's remarks, and began researching the link between stressed-out, achievement-driven behavior and heart disease. In 1959, they identified a type of behavior pattern they called Type A—highly competitive, very concerned with time management, and aggressive—and found that patients with this behavior pattern had seven times the frequency of clinical coronary artery disease compared to other groups.

The pair also created a Type B label, which basically encompassed behaviors and attitudes that weren't defined as Type A. People with Type B behavior were easy-going and enjoyed lower levels of stress, and while they may have been just as ambitious and driven, they seemed more secure and steady. The pair wrote a popular 1974 book about their research, Type A Behavior and Your Heart, which helped spread their ideas in the general consciousness. And while their initial emphasis was on behavior patterns, not entire personalities, the public quickly began referring to Type A and Type B personality types.

Over the next few years researchers began accepting that there could be a link between Type A behaviors, especially hostility, and lethal heart failure. The picture of the fuming man with high blood pressure who succumbs to a rage-induced heart-attack isn't just a cliché, Whitbourne says. (In fact, some modern studies have supported the idea of an increased risk of heart attack after a bout of intense anger.)

But as time went on, researchers began to notice quite a few problems in the Type A/Type B paradigm. In part this was because our understanding of coronary heart disease improved, and doctors and physiologists began to better understand how diet, physical activity, genetics, and the environment relate to blood pressure and cholesterol. As the decades went on, it became apparent that aggressive personality alone was severely limited in its ability to predict heart disease.

Outside the implications for human health, psychologists also began to critique the Type A/Type B system of personality labeling as reductionist, arguing that it lumped together many different traits and folded them under one of two extremely large umbrellas. Many psychologists now feel that human behavior is too complex and intricate to be described in such a binary way: People might be driven and organized, but not necessarily hostile and prone to angry outbursts. People might also be irritable or impatient, but perhaps rarely cross the threshold into hostility.

"It's not that we don't believe in it anymore," Penn State University psychologist John Johnson tells Mental Floss. "It's just that it's run its course. Type A does have a lot of components, but those are components that can be better explained in other ways in personality psychology."

One prominent newer system for describing personality and behavior is the Five Factor Model, developed in 1961 but not reaching academic prominence until the 1980s. The Five Factor Model assesses personality through five domains: openness, conscientiousness, neuroticism, extraversion, and agreeableness. Johnson likens its impact in personality psychology to the Periodic Table of Elements for chemistry.

Many Type A traits, Johnson says, are probably better described under the Five Factor Model. For example, striving for achievement, a big part of Type A personality behavior, would easily fall under high conscientiousness. Type As might also score high on extraversion, but low on agreeableness, since they're less attuned to see others as collaborators.

But although many psychologists feel the Type A and B model has outlived its usefulness, they say it has an important legacy in modern psychology. "The study of Type A and related personality traits really revolutionized behavioral medicine and behavioral health," Whitbourne says. "There are many psychologists that look at behavior and health hand-in-hand," and much of this work has a foundation in what Type A pioneered, according to Whitbourne.

So if many psychologists (not to mention cardiologists) feel the framework is outdated, why do we still call people Type A? According to Johnson, one of the biggest reasons probably has to do with how easy it is to recognize. "We all know people who are very driven and single-minded about achieving something, but they don't treat other people very well," he says. "It's a familiar thing to most of us."