Writing and Style Basics
2 | When to Use the Past and Present Tense of Verbs
Key Point
Best Practices
Scientific papers and proposals contain a mixture of verb tenses, and it can be challenging to know which tense to use. The tense of a verb is used to distinguish among past, present, or future times. In scientific documents, the past tense is used to discuss actions that occurred in the past. Hence, the methods and results sections are written primarily in the past tense. For example, “fluorescence was measured on a spectrofluorometer,” “the results showed that treatment A worked better than treatment B.”
The present tense is used when referring to well known facts or previously published research that is now widely considered to be factual. For example, “cancer is one of leading causes of death in the United States,” “a previous study demonstrated that immune checkpoint inhibitors are useful for treating advanced melanoma.” The present tense is used in these situations because the fact itself is not expected to change over time. Therefore, the present tense is used frequently in the introduction section of a paper, and it also may be used in the discussion. Additionally, the present tense is used when referring directly to a table or figure, for example, “Figure 1 shows that the tumors decreased in size over the course of three weeks.”
These general guidelines will apply to most scientific writing projects. However, check the journal’s author guidelines for any specific tense advice and follow it. While it is rare, a few journals prefer authors use present tense for their own results. The author guidelines should always be given preference if there is any discrepancy as to what style should be used in a scientific paper.
