Although English uses an elaborate system of tenses, simple past and simple present are the most common tenses in research papers, supplemented by present perfect and past perfect. The word ‘perfect’ in this case means ‘made complete’ or ‘completely done,’ and ‘perfect’ tenses are used in describing two events and specifying how the two are related with respect to time.
A typical research paper follows the IMRaD format, and how frequently a given tense is used varies with the section of the paper: the introduction, for example, uses a mix of the present tense and the past tense whereas the past tense dominates the results section. Here is a brief guide to using the four variants, namely simple past, simple present, present perfect, and past perfect.
Simple past: Use simple past to describe specific actions or events that occurred in the past and that are not being linked to the present in the same sentence. Here are some sentences in simple past. ‘We selected 5 plants at random.’ ‘Tanaka reported that 1000 grains of wheat weighed 40 grams.’ ‘Watson and Crick published their landmark paper on the structure of DNA in 1953.’
Simple present: Use simple present for stating what is generally true and unlikely to change, as in ‘The sun rises in the east,’ ‘Human babies generally start speaking when they are two years old’, and ‘In July and August, it rains in most parts of India.’ Use simple present also to indicate research results that you believe to be true and relevant to your present research, as in ‘Robinson maintains that soaking seeds in strong acids help in breaking seed dormancy.’ Lastly, simple present is used when talking about the research paper that you are writing, as in ‘Section 2.3 discusses the advantages of soaking seeds before sowing them.’
Present perfect: Use present perfect to talk about a past event that is linked to the present, to talk about trends, or about events that have ended or occurred recently or still continuing, as in ‘The use of cell phones or mobile phones to access the Internet has increased recently’ and ‘Multi-megawatt turbines have been used in Europe for offshore sites.’
Past perfect: Use past perfect to describe two related past events that occurred at different times in the past, as in ‘By the time they were sown, the seeds had already germinated’ and ‘Those candidates that had been exposed to radiation earlier were excluded.’
To enhance your knowledge about writing research papers, you could refer to the following articles: