The memory of science: Inflation, myopia, and the knowledge network

Research output: Contribution to journalArticle


  • Raj K. Pan
  • Alexander M. Petersen
  • Fabio Pammolli
  • Santo Fortunato

Research units

  • University of California Merced
  • Polytechnic University of Milan
  • CADS
  • Indiana University Bloomington


Scientific production is steadily growing, exhibiting 4% annual growth in publications and 1.8% annual growth in the number of references per publication, together producing a 12-year doubling period in the total supply of references, i.e. links in the science citation network. This growth has far-reaching implications for how academic knowledge is connected, accessed and evaluated. Against this background, we analyzed a citation network comprised of 837 million references produced by 32.6 million publications over the period 1965-2012, allowing for a detailed analysis of the 'attention economy' in science. Our results show how growth relates to 'citation inflation', increased connectivity in the citation network resulting from decreased levels of uncitedness, and a narrowing range of attention - as both very classic and very recent literature are being cited increasingly less. The decreasing attention to recent literature published within the last 6 years suggests that science has become stifled by a publication deluge destabilizing the balance between production and consumption. To better understand these patterns together, we developed a generative model of the citation network, featuring exponential growth, the redirection of scientific attention via publications' reference lists, and the crowding out of old literature by the new. We validate our model against several empirical benchmarks, and then use perturbation analysis to measure the impact of shifts in citing behavior on the synthetic system's properties, thereby providing insights into the functionality of the science citation network as an infrastructure supporting the memory of science.


Original languageEnglish
Pages (from-to)656-678
Number of pages23
JournalJournal of Informetrics
Issue number3
Publication statusPublished - 1 Aug 2018
MoE publication typeA1 Journal article-refereed

    Research areas

  • Attention economy, Citation inflation, Citation network, Models of science, Monte Carlo simulation, Reference distance

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