One of your authors was once involved in a research study where a newly developed pain drug was being tested. all participants complete a series of tasks intended to represent various types of somatic pain (e. g., a sharp, fast pain, a dull ache, and were asked to report how much pain they experienced during each task. the pain series was completed both during an initial visit to the lab, and during a second visit about a week later. prior to completing the tasks during the second visit, participants received either the new pain drug, or a placebo. what primary ethical guidelines apply to this experiment