The diachronic change of research article abstract difficulty across disciplines: a cognitive information-theoretic approach

Text difficulty refers to the ease with which a text can be read and understood, and the difficulty of research article abstracts has long been a hot topic. Previous studies have found that research article abstracts are difficult to read in general and that abstracts have gradually become more and more difficult. However, the widely used measurements, such as FRE and SMOG, have long been criticized in that they use only simplistic and surface-level indicators as proxies for complex cognitive processes of reading, and the sophisticated cognitive theory and Natural Language Processing/machine learning-based methods seem not that easy to use and interpret. A theoretically sound and methodologically neat measurement of text difficulty should be called for. Besides, the diachronic changes of abstract difficulty across disciplines have been under-researched. To address these issues, this study adopted a cognitive information-theoretic approach to investigate the diachronic change of text difficulty of research article abstracts across the areas of natural sciences, social sciences, and humanities. 1890 abstracts were sampled over a period of 21 years, and two indexes, i.e. entropy from information theory and mean dependency distance from cognitive science, were employed for the calculation of cognitive encoding/decoding difficulty. The results show that in general, the cognitive encoding difficulty of abstracts has been increasing in the past two decades, while the cognitive decoding difficulty of abstracts has been decreasing. Regarding the disciplinary variations, the humanities show no significant diachronic change in encoding difficulty, and the social sciences show no significant diachronic change in decoding difficulty. These phenomena can be attributed to the traits of abstracts, the nature of academic knowledge, the cognitive mechanism in human languages and the features of different disciplines. This study has implications for the innovations in theories and methods of measurement of text difficulty, as well as an in-depth understanding of the disciplinary variations in academic writing and the essence of research article abstracts for research article writers, readers, the scientific community, and academic publishers.