Use past tense (“They concluded…”) or present perfect (“They have concluded…”) when discussing another author’s research or writing since the research and/or the writing occurred in the past.
Use past tense (“I discovered…”) when discussing research you have completed.
Use present tense (“I know…”) for ongoing events or studies—or to discuss your conclusions and any implications of the results.
Use future tense (“I will be…”) for anything that has not yet happened.
For more information on verb tenses, review pages 65-66 and 77-78 in the Publication Manual of the American Psychological Association, 6th Ed. (2010).