Read this article about when to use the present simple, past simple, and present perfect verb tenses. A common mistake in writing is to shift verb tenses, such as by writing in the present tense and then shifting to the past tense. To avoid this, try to choose the appropriate verb tense and use it consistently throughout your writing.
These three verb tenses account for approximately 80% of the verb tense use in academic writing. This handout will help you understand how present simple, past simple, and present perfect verb tenses are used in academic writing.
The present simple tense is the basic tense of most academic writing. Use this as your first choice unless you have a good reason to use another tense. Specifically, the present simple is used:
The dinoflagellate's TFVCs require an unidentified substance in fresh fish excreta (Environmental Science) 
There is evidence that …
Past simple tense is used for two main functions in most academic fields:
…customers obviously want to be treated at least as well on fishing vessels as they are by other recreation businesses. [General claim]
De Young (1987) found the quality of service to be more important than catching fish in attracting repeat customers. [Specific supporting evidence] (Marine Science)
We conducted a secondary data analysis … (Public Health)
Descriptional statistical tests and t-student test were used for statistical analysis. (Medicine)
The control group of students took the course previously … (Education)
The present perfect is mostly used for referring to previous research in the field or to your own previous findings. Since the present perfect is a present tense, it implies that the result is still true and relevant today.
Some studies have shown that girls have significantly higher fears than boys after trauma (Pfefferbaum et al., 1999; Pine &; Cohen, 2002; Shaw, 2003). Other studies have found no gender differences (Rahav &; Ronen, 1994). (Psychology)
There have been several investigations into …
More recently, advances have been made using computational hydrodynamics to study the evolution of SNRs in multi-dimensions …(citation) … [previous research]
However, a similar problem exists in the study of SNR dynamics. [gap] (Astrophysics)
 Example reproduced from Penrose & Katz, 2004, p. 330
 According to Hawes and Thomas, 1997
Biber, Douglas et al. Longman Grammar of Spoken and Written English. Longman, 1999.
Hawes, Thomas, and Sarah Thomas. "Tense Choices in Citations". Research into the Teaching of English, 31 (1997): 393-414.
Hinkel, Eli. Teaching Academic ESL Writing. Lawrence Erlbaum, 2004.
Penrose, Ann, and Steven Katz. Writing in the Sciences: Exploring the Conventions of Scientific Discourse. 2nd ed. Pearson Longman, 2004.
Swales, John, and Christine B. Feak. Academic Writing for Graduate Students: Essential Tasks and Skills. 2nd ed. University of Michigan Press, 2004.
Source: The University of North Carolina at Chapel Hill Writing Center, https://writingcenter.unc.edu/tips-and-tools/verb-tenses/
This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.