I am a psychologist. This is what your signature says about your personality

For years, Donald Trump’s distinctive, large and bold signature has captured the public’s attention. Not only was it recently revealed that his signature appeared in the book that Jeffrey Epstein received for his 50th birthday, but it sits well with Trump’s long history of brazen self-harm. “I like my signature, I really do,” he told military leaders on September 30, 2025. “Everybody likes my signature.”

His signature is also of interest to me because of my decades-long interest in the relationship between signature size and personal characteristics, and my occasional academic research.

A longtime social psychologist who has studied America’s elite, I discovered an involuntary experiment more than 50 years ago as an undergraduate.

The link I discovered at the time – and has since been replicated by many studies – is that the size of a signature depends on a person’s mood and sense of self.

Signature size and self-esteem

In 1967, during my senior year of college, I was a student worker in the psychology library at Wesleyan University. My job, four nights a week, was to check the books and put away the books that were returned.

As students or faculty check out the books, they are asked to sign their name on an orange, unlinked card found in each book.

At one point I noticed a pattern: when professors signed books, they used a lot of space to sign names. When students reviewed them, they used very little space, leaving more space for future readers.

So I decided to study my observations systematically.

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I collected at least 10 signatures for each faculty member and compared samples of students’ signatures with the same number of letters in their names. After measuring the amount of space used by height time width, I found that eight out of nine faculty members use more space to sign their names.

To test age and status, I conducted another study in which I compared the signatures of blue-collar workers such as custodians and groundskeepers who worked at the school with a sample of faculty and a sample of students—again matched for letter counts, this time on 3-by-5-inch cards. Blue-collar workers used more space than students but less than professors. I have come to the conclusion that age is at play, but so is the situation.

When I told psychologist Carl Scheib, my favorite teacher, about my findings, he said I could measure his book signings, which he had been signing for more than a decade since his freshman year of college.

As can be seen in the chart, his book signatures are often large. They had a big jump from freshman year to senior year, decreased a bit when he entered graduate school, and then increased in size when he finished his Ph.D. and attended Wesleyan College.

I did a few more studies and published a few articles and came to the conclusion that the size of a signature is related to self-esteem and a measure of what I call “situational awareness.” I have seen this pattern exist in various environments, including in Iran – where people write from right to left.

Narcissistic relationship

Although my recent research included a book on the CEOs of Fortune 500 companies, it never occurred to me to look up the signatures of these CEOs.

However, this happened to some researchers after 40 years. In May 2013, I received a call from the editor of the Harvard Business Review as I worked on a signature piece. They planned to interview University of Maryland accounting professor Nick Seibert about the possible relationship between signature size and narcissism in CEOs.

While Seibert told me that his research found no direct evidence for a positive relationship between the two, I was still intrigued by the possibility of a connection he suggested.

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So I decided to test it using a sample of my students. I asked them to sign a white 3 by 5 card as they wrote the check, and then I gave them 16 items of widely used drugs.

See, Seibert was right to draw a link: there is a significant positive correlation between signature size and narcissism. Although my sample size was small, after this link Seibert tested two different samples of his students. And he found the same significant and positive correlation.

Others soon began using signature scales to assess narcissism in CEOs. By 2020, increased interest in the topic led to the publication of an article in the Journal of Management that included the signature scale as one of five methods for measuring narcissism in CEOs.

A growing field

Now, nearly six years later, researchers have used signature measurements to detect drug addiction in CEOs and other senior corporate positions such as CFOs. This relationship has been found not only in the United States, but also in countries including England, Germany, Uruguay, Iran, South Africa and China.

In addition, some researchers have studied the effects of large and small signs on the audience. For example, in a recent article in the Journal of Philanthropy, Canadian researchers reported on three studies that systematically varied the size of a donor’s signature to see if it affected the size of the donation. In one of their studies, they found that increasing the size of the sender’s signature generated twice as much revenue.

A surprising resurgence of research using signature measures to assess narcissism leads me to several conclusions.

For example, the signature measure is more powerful than the measure of specific aspects of personality when I was a bright student working in a college library in 1967.

In fact, as I once came to the conclusion, the size of the signature is not the only indicator of status and self-esteem. It’s also, as recent studies show, indicative of drug addiction — the kind that many argue is represented by Trump’s big, bold signature.

Where this research leads is anyone’s guess, at least for those who noticed something interesting about signature sizes years ago.