A fascinating new working paper finds that men are far more likely than women to back up their arguments with appeals to a higher authority: themselves.
When an academic writes a research paper, it is common practice to give citations for various facts and assertions. It is not enough, for instance, to simply assert that "the global rise of the hyperdiverse ant genusPheidole is an evolutionary epic with many subplots." You need to cite biologist Corrie S. Moreau's 2008 paper on "Unraveling the evolutionary history of the hyperdiverse ant genus Pheidole" to make that argument.
In academia, article citations like these are a marker of authority and influence: If your work gets cited by others hundreds of times, that's a good indicator that you're making a mark on your field. Universities often factor in citation counts when making decisions about hiring, tenure and pay.
As it turns out, academics have a handy tool at their disposal for juicing their citation counts: They cite themselves. There's nothing inherently shady about this practice. If you're an expert in a relatively obscure field like ant taxonomy, you're probably going to need to cite your previous work because few people are doing similar work.
So Molly M. King and her colleagues at Stanford University, the University of Washington and New York University set out to find how often this so-called "self-citation" happens. They did so by examining a massive database of academic work: 1.5 million research papers in JSTOR, a digital library of academic books and papers published between 1779 and 2011.
What they found, first of all, is that self-citation represents a significant chunk of all academic citations. There were 8.2 million citations contained in the 1.5 million papers they studied. Nearly 775,000 of those citations, or about 10 per cent of them, were of authors citing their own work.
For some individuals, the share of self-citations was much higher. They give an example of one "prominent scholar" (they don't name names, because academia is a small world) who has received more than 7,000 citations of his work. More than a fifth of those citations came from himself.
Science news in pictures
Science news in pictures
1/20 'Tiny vampires' existed millions of years ago
Scientists have discovered that microscopic 'vampire' amoebae existed hundreds of millions of years ago, and they may have been some of the first predators on Earth. By examining ancient fossils with an electron microscope, paleobiologist Susannah Porter from UC Santa Barbara discovered tiny holes which may have been drilled by vampiric microbes. The tiny creatures are believed to be the ancestors of modern Vampyrellidae amoebae, and punctured holes in their prey before sucking out the contents of their cells
2/20 Kepler 62f
An Earth-like planet orbiting a star 1,200 light years away could have conditions suitable for life, say scientists. Kepler 62f is about 40 per cent larger than the Earth and may possess surface oceans. It is the outermost of five planets circling a star that is smaller and cooler than the sun discovered by the American space agency Nasa's Kepler space telescope in 2013
3/20 Vegetables grow well in soil from Mars
Scientists have taken a leaf out of the script of The Martian by showing how easy it would be to grow your own veg on the Red Planet. In the hit Ridley Scott film, a stranded astronaut played by Matt Damon uses his botanical skills to cultivate potatoes. Now his success has been emulated by researchers in the Netherlands who harvested tomatoes, peas, rye, rocket, radish and cress raised on simulated Martian soil supplied by Nasa
4/20 Ancient Roman 'leisure complex' unearthed in Jerusalem
An ancient Roman estate complete with its own wine press and bathhouse has been unearthed in Jerusalem. A series of buildings dating back at least 1,600 years were discovered underneath the city's famous Schneller Orphanage which operated on the site from 1860 until the end of the Second World War, when it was turned into an army base. The ruins were discovered by archaeologists from the Israel Antiquities Authority who were excavating the site ahead of building new flats for the city's Orthodox Jewish community
5/20 Scientists discover possible new species of deep-sea octopus nicknamed 'Casper'
Scientists believe they may have found a new species of octopus likened in appearance to Casper, the friendly cartoon ghost. Researchers with the US National Oceanic and Atmospheric Administration made the discovery by chance as they searched the seabed on an unrelated mission collecting geological samples. Teams were operating an unmanned submarine on the Pacific Ocean floor at depths of more than four kilometres (two-and-a-half miles) in the Hawaiian Islands when they spotted the unusual creature
6/20 Black hole captured eating a star then vomiting it back out
Astronomers have captured a black hole eating a star and then sicking a bit of it back up for the first time ever. The scientists tracked a star about as big as our sun as it was pulled from its normal path and into that of a supermassive black hole before being eaten up. They then saw a high-speed flare get thrust out, escaping from the rim of the black hole. Scientists have seen black holes killing and swallowing stars. And the jets have been seen before.But a new study shows the first time that they have captured the hot flare that comes out just afterwards. And the flare and then swallowed star have not been linked together before
7/20 'Male and female brains' aren't real
Brains cannot be categorised into female and male, according to the first study to look at sex differences in the whole brain. Specific parts of the brain do show sex differences, but individual brains rarely have all “male” traits or all “female” traits. Some characteristics are more common in women, while some are more common in men, and some are common in both men and women, according to the study
8/20 Dog-sized horned dinosaur fossil found shows east-west evolutionary divide in North America
A British scientist has uncovered the fossil of a dog-sized horned dinosaur that roamed eastern North America up to 100 million years ago. The fragment of jaw bone provides evidence of an east-west divide in the evolution of dinosaurs on the North American continent. During the Late Cretaceous period, 66 to 100 million years ago, the land mass was split into two continents by a shallow sea. This sea, the Western Interior Seaway, ran from the Gulf of Mexico to the Arctic Ocean. Dinosaurs living in the western continent, called Laramidia, were similar to those found in Asia
9/20 Asteroid to skim past Earth on Halloween 2015
A huge asteroid is set to skim by Earth on Halloween, just three weeks after it was first spotted. The rock is travelling through space at 78,000 miles per hour, and will fly past the Earth at a distance of only 300,000 miles – only slightly further away than our moon, and easily close enough for Nasa to class it a potentially hazardous object. The asteroid is bigger than a skyscraper
10/20 Life on Earth appeared hundreds of millions of years earlier than previously thought
Life may have come to earth 4.1 billion years ago, hundreds of millions of years earlier than we knew. The discovery, made using graphite that was trapped in ancient crystals, could mean that life began "almost instantaneously" after the Earth was formed. The researchers behind it have described the discovery as “a potentially transformational scientific advance”. Previously, life on Earth was understood to have begun when the inner solar system was hit by a massive bombardment from space, which also formed the moon's craters
11/20 Earth could be at risk of meteor impacts
Earth could be in danger as our galaxy throws out comets that could hurtle towards us and wipe us out, scientists have warned. Scientists have previously presumed that we are in a relatively safe period for meteor impacts, which are linked with the journey of our sun and its planets, including Earth, through the Milky Way. But some orbits might be more upset than we know, and there is evidence of recent activity, which could mean that we are passing through another meteor shower. Showers of meteors periodically pass through the area where the Earth is, as gravitational disturbances upset the Oort Cloud, which is a shell of icy objects on the edge of the solar system. They happen on a 26-million year cycle, scientists have said, which coincide with mass extinctions over the last 260-million years
12/20 Genetically-engineered, extra-muscular dogs
Chinese scientists have created genetically-engineered, extra-muscular dogs, after editing the genes of the animals for the first time. The scientists create beagles that have double the amount of muscle mass by deleting a certain gene, reports the MIT Technology Review. The mutant dogs have “more muscles and are expected to have stronger running ability, which is good for hunting, police (military) applications”, Liangxue Lai, one of the researchers on the project. Now the team hope to go on to create other modified dogs, including those that are engineered to have human diseases like muscular dystrophy or Parkinson’s. Since dogs’ anatomy is similar to those of humans’, intentionally creating dogs with certain human genetic traits could allow scientists to further understand how they occur
13/20 Nasa confirms Mars water discovery
Nasa has announced that it has found evidence of flowing water on Mars. Scientists have long speculated that Recurring Slope Lineae — or dark patches — on Mars were made up of briny water but the new findings prove that those patches are caused by liquid water, which it has established by finding hydrated salts.
14/20 Bees in the Rocky Mountains are evolving shorter tongues
With warmer summers, flowers in the Rockies have become shallower and more suited to shorter-tongued bees
15/20 The majority of the UK public believe in aliens
The titular alien character from 2011's 'Paul' - a poll has found the majority of the public in Britain, Germany and the US believe that intelligent life is out there in the universe
16/20 Researchers discover 'lost world' of arctic dinosaurs
Scientists say that the new dinosaur, known as Ugrunaaluk kuukpikensis, “challenges everything we thought about a dinosaur’s physiology”. Florida State University professor of biological science Greg Erickson said: “It creates this natural question. How did they survive up here?”
17/20 Scientists find exactly what human corpses smell like
New research has become the first to isolate the particular scent of human death, describing the various chemicals that are emitted by corpses in an attempt to help find them in the future. The researchers hope that the findings are the first step towards working on a synthetic smell that could train cadaver dogs to be able to more accurately find human bodies, or to eventually developing electronic devices that can look for the scent themselves.
18/20 The Syrian civil war has caused the first ever withdrawal from the 'doomsday bank'
Researchers in the Middle East have asked for seeds including those of wheat, barley and grasses, all of which are chosen because especially resistant to dry conditions. It is the first withdrawal from the bank, which was built in 2008. Those researchers would normally request the seeds from a bank in Aleppo. But that centre has been damaged by the war — while some of its functions continue, and its cold storage still works, it has been unable to provide the seeds that are needed by the rest of the Middle East, as it once did.
19/20 A team of filmmakers in the US have made the first ever scale model of the Solar System in a Nevada desert
Illustrations of the Earth and moon show the two to be quite close together, Mr Overstreet said. This is inaccurate, the reason being that these images are not to scale.
20/20 Academics claim a full bladder makes for a better liar
People lie more convincingly if they have a full bladder, according to research by academics at California State University. Iris Blandón-Gitlin's team asked 22 students to lie to a panel of interviewers. Half were given 700ml to drink before the interview and the other half, just 50ml. The students with the full bladders showed fewer signs that they were lying and their untrue answers were longer and more detailed, meaning interviewers were less able to detect that they were telling porkies. PM David Cameron has previously attested to giving speeches on a full bladder.
But more strikingly, King and her colleagues found a huge difference in self-citation patterns between men and women. "Over the years between 1779-2011, men cite their own papers 56% more than women do," they found. And in recent decades, men have stepped up their self-citation game relative to women: "In the last two decades of our data, men self-cite 70 per cent more than women."
This self-citation gap held true across every major academic field the authors studied, including biology, sociology, philosophy and law. In a footnote, the paper's authors — three women and two men — dryly note that the pattern holds among themselves as well: "The men authors of this paper cite themselves at nearly three times the average rate of the women authors."
King and her colleagues offer a number of hypotheses for why men may be more likely to cite themselves. For starters, studies have shown that men generally have a higher opinion of their own abilities than women do. And they typically face fewer social penalties for self-promotion. "Gendered perceptions of self-promotion likely influence perceptions of self-citation, which could be viewed as a form of self-promotion in the academic workplace," King and her colleagues write.
There's also the simple fact that men tend to publish more, particularly early on in their careers — a time when many female academics might be grappling with the challenges of balancing career with maternity leave. If you've published more papers, you have more chances for citing your own work.
Regardless of the underlying mechanism, the self-citation disparity has a real-world impact on female academics' careers. Academics are more likely to cite papers that are already well-cited, so citing yourself means more citations from others. And more citations means better career-advancement opportunities.
This phenomenon probably contributes to women's continued under-representation on college faculties. Women have earned at least half of all bachelor's degrees in science and engineering fields since the late 1990s, according to the National Science Foundation, but as of 2013, they represent fewer than a quarter of university faculty members in those fields.
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