Beneficence is the concept in research that the researcher should consider the welfare of the test subjects and research participant as part of any research or clinical trial. Although this concept seems apparent to most people and researchers, items being tested are not always safe or harm-free.
For instance, asking some types of questions may cause unpleasant feelings or memories to arise in the subjects and make them feel bad. In this case, a researcher must make a cost-benefit analysis to decide whether the end results are worth the possible cost or harm. In the past, when ethics were not as stressed as they are today, many experiments were undertaken that had negative results on the subjects.