Psychological researchers must debrief human test subjects at the end of every experiment.
The current code of ethics in psychological research states that researchers absolutely must debrief human test subjects at the end of every study regardless or whether or not harm or deception was involved.
Debriefing a subject after a study is an essential opportunity for the researcher to explain the purpose and aim of the study to the subject, make sure the subject is not harmed or mentally disturbed, clarify why deception was used (if deception was involved) and overall, to clarify any questions or doubts the subject might have.