To be a highly-cited researcher is a mark of achievement in science. The number of times someone’s work gets referenced indicates influence: If an author hasn’t been cited, they haven’t had much effect on their field of study; if they’ve been cited hundreds of times, their research is probably pretty important. Unless they’re just citing themselves, that is.
A study published in PLoS Biology earlier this month tracked self-citation among 100,000 of the most highly-cited academics, and found that some people are referencing their own work—and that of their close collaborators—an awful lot. The worst offender (as calculated by percentage of self-citations), an analytic chemistry professor named Oleg Mikhailov, has received 98 citations between 1989 and 2018, more than 94% of which are from himself or his co-authors.
The dataset does not include gender, and many of the authors are identified by initials only, making it difficult to evaluate gender breakdown at scale. But among the top 25 self-citers, all of whom have received more than 68% of their citations ‘in-house’, only one is a woman.
In total, 252 people from the database of 100,000 highly-cited researchers have received at least 50% of their citations from themselves or their co-authors. Among these, scientists from the United States feature most prominently. The chart below shows all those countries that have three or more scientists in this group.
But though the United States is certainly home to a large number of highly self-citing scientists, the country does not feature in the top 20 countries by median percentage of self-citation in the paper’s database.
Meanwhile, when it comes to fields of research, ‘general physics’ has the most scientists for whom self-references make up 50% or more of total citations. High rates of self-citation don’t necessarily indicate scientific narcissism: Jeroen Baas, director of analytics at scientific publisher Elsevier and co-author of the study, told Nature that papers in physics often have multiple authors, which could lead to higher rates of self-citation.
Nor is self-citation necessarily a sign of poor scholarship. If someone is both influential and prolific in their field, it stands to reason that they would both cite their own work and be widely cited by others.
But a high percentage of citations coming from the author themself could suggest an attempt to artificially inflate prominence. Many universities rely on citations as a sign of productivity and influence, using citation data to determine promotions and bonuses. As Nature notes, a 2017 study found that scientists in Italy increased how often they cited themselves following a 2010 policy that tied promotions to productivity thresholds. “Those with greater than 25% self-citation are not necessarily engaging in unethical behavior, but closer scrutiny may be needed,” John Ioannidis, a scientist at Stanford University who led the research, told Nature.