One of your authors was once involved in a research study where a newly developed pain drug was being tested. All participants completed a series of tasks intended to represent various types of somatic pain (e. g., a sharp, fast pain, a dull ache, etc.), 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? Would any other guidelines apply if the study participants were made up of a group of patients actively receiving treatment for a pain disorder?