The Science of Personality
by John M. Oldham, M.D., M.S.

As human beings, what determines the ways in which we are alike and the ways in which we are different? What makes each of us unique? Are we born that way and do we stay that way for life, or do we—can we—change? These questions have fascinated us for centuries, but not until recently have we had the tools to really tackle the science of human behavior. Now we know, for example, that our genes do play an important role in determining who we are—that is, that different personality types are, at least in part, inherited. We sometimes refer to this component of personality as “temperament”; the way each of us is hard-wired from birth can predispose us to be an adventurer, a loner, a brainy nerd, or a sentimental puddle of tears.

But we also know that experience counts. Our brains develop gradually and are not fully formed until our mid-twenties. What happens during those early years will shape not just our behavior (anxious, belligerent, placid, trusting, crafty), but indeed, the entire neurobiology of our brains. The hard-wiring we inherit is rudimentary at birth; how successfully (or not) our maturing circuits connect with each other as we navigate the stages of development from infancy to young adulthood is crucial. Bad luck, such as early trauma or neglect, can interrupt or derail the process; good luck, such as having a supportive, caring family, can facilitate a sturdy outcome.


I was taught that by the time we reach our twenties we have all of the brain cells we’ll ever have, and that our only saving grace is that we have a lot of spares. That timeworn belief, however, turns out to be wrong! New technology such as brain imaging has revealed that new brain cells can be “born” in parts of the brain throughout the life cycle, even into old age. And we have learned that the brain is remarkably flexible and adaptive, able to enrich itself or adjust, assisted by things like medication, exercise, or even psychotherapy. These findings help us address one of the questions posed above: can we change? Indeed we can.

I have been especially interested in the field of personality throughout my career, stemming from my training days in psychiatry and psychoanalysis at Columbia University College of Physicians and Surgeons in New York. How to understand motivated human behavior—from the wide variety of types and styles to the extremes of behavior that can be unleashed in some of us—is endlessly fascinating and challenging. Psychiatrists, psychologists, sociologists, and other students of human behavior have struggled for decades to devise a standard system to classify the most common personality patterns—the main ways that some of us are like each other, and the main ways that others share common features that are different from our own.

The classification system from which the NPSP25 evolved was developed from the American Psychiatric Association (APA) personality disorder system, which defines and provides diagnostic criteria for the often disabling personality disorders. The diagnostic criteria for the personality disorders are published in the APA’s Diagnostic and Statistical Manual of Mental Disorders, the most recent of which is the fifth edition, DSM-5, published in 2013.

How Personality Is Like Blood Pressure

Personality disorders are hard to change. Some can be helped enormously by psychotherapy, but it takes effort and persistence. They are long-term patterns of inflexible and maladaptive behavior that put people in conflict with family members, employers, friends, and colleagues and disrupt functioning in all aspects of life. People with disordered personality patterns usually do not realize that there is anything amiss with them; indeed, they often believe the fault lies with anyone else but themselves.

Personality styles, however, are flexible and adaptive. You may be set in yours ways, but if given sufficient incentive–to meet your goals, to cement a relationship, to cope with stress and change, to feel better about yourself, to enjoy your life–you can change. Think of it on a spectrum, or dimension, like blood pressure. You need it to be alive, but too much or too little of a necessary and good thing can become a problem. Likewise, each of us has a personality, necessary to function in this world. But if certain personality traits are too prominent (or maybe too minimal), problems can ensue.

Consider Obsessive-Compulsive personality disorder, characterized by traits such as rigid perfectionism, inability to express emotions, stubbornness, indecisiveness, and excessive devotion to work–all to an extreme degree. But pull these traits back toward the center of the scale, and they describe what we call Conscientious personality style, characterized by clarity about doing the right thing the right way, willingness to work hard and persevere, prudence, attention to order and detail–features that can lead to success rather than failure. If you are a strongly Conscientious person, you may sometimes seem like a workaholic, but you can call a halt at some point, perhaps at the suggestion of someone you trust, and you can chill, return to the task energized, and accept that the finished product is good enough.

Normal For You

The dimensional nature of normal, adaptive personality style is the guiding principle of the NPSP25 and its two predecessors. Journalist and author Lois B. Morris, who has long written about mental health, and I have, in effect, “turned the volume down” on all the DSM personality disorders that have been published or proposed in the last three editions of the diagnostic manual. Aided by research using the test and clinical experience, we have descriptively transformed each personality disorder into a nonpathological, adaptive, useful personality style, and we devised a self-assessment test called The Personality Self-Portrait that assesses, scores, and displays one’s entire personality profile. The first edition of the test was included in The Personality Self-Portrait, a book published in 1990. This was followed by The New Personality Self-Portrait, with a second edition of the test, in 1995—a volume that has been continuously in print since then. Then as now, the result portrays what is normal for you: your Self-Portrait graph in 14 dimensions of personality style.

In 2014, we welcomed research and clinical psychologist Alok Madan, MPH, PhD to our team. The NPSP25 emerged following his ongoing analysis of the results of over 12,000 test results over three years. It makes its debut here as an electronic self-assessment test. In addition to the Self-Portrait graph, we now offer normative scoring, by which you can compare your personal results to those of the international sample.

And if you feel there are a few rough patches that you’d like to smooth out and you are motivated by what you see in yourself and in comparison to others, you can change. In fact, you will change, as those of our subjects who have taken the test repeatedly over the years have found.

The New Personality Self-Portrait 25 Logo