Exponential authorship inflation in neuroscience and psychology from the 1950s to the 2020s

How many researchers does it take to publish an article in top journals in neuroscience and psychology? Manually coding 42,580 articles spanning 1879-2021 from 32 journals, we examined the evolution of authorship size and its rate of change. Moreover, we assessed the driving forces behind these changes. We found that, starting from the 1950s but not earlier, the average authorship size per article in neuroscience and psychology has increased exponentially, growing by 50% and 31% over the last decade and reaching a record high of 10.4 and 4.8 authors in 2021, respectively. Single-authored articles have become a rarity today, particularly in primary research articles: 1.7% in neuroscience and 2.2% in psychology in 2019-2021 (vs. 5.7% and 11.2% in review articles). With the withering of sole authors rises a new type of authorship, group authors (e.g., a consortium). Group authorship was rare before 2000, but in 2019-2021, it appeared in 4.1% of articles in neuroscience, mostly in genetics, neuroimaging, and disease-outnumbering single-authored articles for the first time-and 0.7% in psychology, mostly in developmental and clinical research. The exponential inflation in authorship size could not be attributed to behaviors of professional editors in profit-oriented journals but aligns with a hybrid epistemic-behavioral-cultural account-an account that integrates multidimensional factors, including increased research complexity, the benefits of collaboration, the rise of government-funded research, changing norms in authorship practices, and biased incentives in evaluation. These findings suggest troubling implications for research reproducibility, innovations, equity/diversity, and ethics, calling for policy deliberations to address potential negative ramifications. (PsycInfo Database Record (c) 2025 APA, all rights reserved).