Senior scientists may generate fewer disruptive breakthroughs than their younger colleagues, but the disruptions they do produce are more likely to endure, according to a new analysis of the publication records of more than 200,000 researchers. The study, published in the Proceedings of the National Academy of Sciences, introduces a new way of measuring scientific disruption that accounts for how long a challenge to established knowledge survives.
Scientific progress typically builds incrementally on prior research, but major advances often come from work that overturns existing knowledge and opens new lines of inquiry. A common way to identify such papers is to look at whether later studies cite them without also citing the earlier research they displaced. Previous work using this measure found that the tendency to produce disruptive work declines over the course of a scientist's career.
Nan Deng of the National Science Library at the Chinese Academy of Sciences and colleagues argue that this conventional measure misses an important dimension: whether disruption lasts. To capture it, the team developed a «persistent disruption index», which tracks whether a disruptive paper is later consolidated or displaced by the work that cites it. The researchers compared how much a paper disrupts the work in its references with how much that paper is itself disrupted by its citing papers.
They define a persistently disruptive paper as one that ranks in the top 5% for reference disruption and the bottom 5% for citation disruption. This combination, they say, filters out what they call «nonreal disruption» — work that overturns previous research but is then quickly overturned itself.
Using bibliographic data from SciSciNet, the team analyzed 206,130 scientists whose careers span more than 40 years. The results showed a clear split across career stages. As scientific careers progress, the probability of producing a disruptive paper decreases, while the probability of publishing a persistently disruptive paper increases. In other words, scientists disrupt less often as they age, but when they do, their work is more likely to endure and be built upon.
The analysis also found that the disruptive work of experienced scientists attracted more attention from both the media and fellow researchers. That greater visibility may help explain why their disruptive contributions persist, the researchers suggest.
The findings carry implications for how science is evaluated and funded. Deng and colleagues note that evaluation and funding systems focused only on immediately visible disruption may overlook the durability of disruptive ideas and the role that experience plays in producing them. A metric that rewards short-term novelty could therefore undervalue the kind of lasting challenge to established knowledge that seasoned researchers appear more likely to deliver.
The study adds nuance to a long-running debate about creativity and age in science. Rather than treating a decline in the frequency of disruptive papers as evidence that older scientists are less valuable to the research enterprise, the new index suggests that their disruptive contributions may simply take longer to reveal their significance — and may prove more durable once they do.
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