Does the academic discipline of a scientist’s doctorate degree accurately capture their disciplinary affiliation decades later? Consider a scientist who earned a doctorate in physics 25 years ago who now studies climate change, publishes primarily in interdisciplinary journals and considers herself a climate scientist. Does “physics” still accurately describe where she fits in science?
A new study led by researchers at Rice University and Michigan State University argues that the answer is often no.
Researchers Gina Pizzo, a lecturer in Rice’s Department of Statistics, and Aaron McCright, professor of sociology at Michigan State, have developed and validated a new way to measure what they call “disciplinarity” — the extent to which scientists remain closely connected to the core of the discipline in which they trained or move toward its boundaries and beyond over the course of their careers.
Published in PLOS One, the study offers a more nuanced way to understand scientific affiliation at a time when researchers increasingly work across traditional academic boundaries. It was tested using survey responses from 4,113 tenure-system science faculty at 83 U.S. research universities. Co-authors of the paper also include Chad Gonnerman of the University of Southern Indiana, Troy Hall of Oregon State University, Kathryn Plaisance of the University of Waterloo and Brian Robinson of Texas A&M University-Kingsville.
“Scientists don’t necessarily stay in the same intellectual box throughout their careers,” said Pizzo, first author of the paper. “Their research questions, collaborators and professional communities can change considerably, and we wanted a way to capture that evolution rather than relying on a single disciplinary label.”
Researchers studying scientists have long grouped them by characteristics such as the field of their highest degree, their department or the discipline with which they identify. But Pizzo and McCright found that such approaches often miss important differences among scientists who technically belong to the same field. Their review of previous surveys found that disciplinary affiliation has frequently been measured using only one or two indicators, which can obscure the ways scientists’ careers diverge as they collaborate across fields or shift the focus of their research.
To address that gap, the researchers created a five-dimensional Disciplinarity Scale. Anchored to a scientist’s doctoral discipline, it measures how closely five aspects of their current professional life still align with that original field: their department, primary professional association, publishing outlets, how their peers perceive their discipline and how they identify themselves. Together, the measure places scientists along a continuum from strong connection to a discipline’s core to broader association with its frontier or beyond.
“Academic disciplines are useful categories, but they aren’t impermeable containers,” said McCright, who is the corresponding author on the study.
The researchers found that scientists tended to have broader disciplinary affiliations the longer they had been out of graduate school. The association was even stronger among scientists with more experience conducting cross-disciplinary research.
“Cross-disciplinary research experience was especially strongly associated with broader disciplinarity” Pizzo said. “When scientists repeatedly work with people who ask different questions, use different methods or publish in different places, those experiences can gradually reshape where they fit within science.”
The scale also helped identify scientists who had formally moved into a different discipline. About 16.6% of respondents reported a current discipline different from that of their doctorate, while roughly 83% remained within their original nominal discipline. But even among scientists who had not formally changed fields, the new measure revealed differences in how closely their current work remained tied to their original discipline.
That distinction could matter for researchers who study how scientists’ backgrounds influence their views, behaviors or approaches to research. If two scientists are both classified as physicists but one works near the traditional core of physics while the other operates largely at the boundary with climate science or materials science, assuming them to be equivalent may hide meaningful differences.
Pizzo and McCright argue that future surveys could pair conventional disciplinary categories with the new scale, allowing researchers to capture both where scientists began and how their disciplinary affiliation has evolved.
This approach may be especially useful as universities and funding agencies increasingly encourage interdisciplinary research aimed at problems that do not fit neatly within a single field.
“We’re not arguing that disciplines no longer matter,” McCright said. “They remain fundamental to how science is organized. But if we want to understand scientists accurately, we also need to account for the ways their relationship to those disciplines can change over time.”