Participants have the right to withdraw from research (and, indeed to withdraw their data from a study)
Deception
Researchers should avoid deceiving participants wherever possible
Protection from harm
Participants should be protected from physical and psychological harm
Confidentiality
Data should be kept confidential
Debriefing
Participants should receive a debrief so that they leave the research in the same state of mind as when they arrived
Benefits from ethical research
It avoids participants from leaving the study in a different (worse) state than when they entered it
It makes replication of the study possible in order to see if the same results would be obtained again (demonstrating that a consistent effect has been observed)
It enhances the reputation of psychology as an academic discipline
Researchers are likely to get other participants for psychological research in the future if they can see that participants are treated well
Drawbacks from ethical research
Placing limits on the sort of research carried out (preventing research that might be really worthwhile from being done)
Reducing the validity of research if participants know the aim of a study (as this can lead to them not behaving how they normally would)
Sampling bias can be a problem if participants are able to withdraw (e.g. you get left with a sample that isn't as representative as it could be)
Insisting on participants being confidential could silence them and prevent them from having people know that a particular result in the study related to them