Informed Consent and a Right to WIthdraw
These first two go hand-in-hand. One of the main rules is that a psychologist cannot simply come up and experiment on you. (S)he has to first let you know that you're in a psychological experiment, and you have to give your consent to participate. However, he doesn't necessarily have to tell you the nature of the experiment, just that you're participating in one.
This brings up another point, what if you don't like the nature of the experiment when it begins? It does seem unfair to get you to agree to be a participant when you don't even know what's coming. This is where the right to withdraw comes in, you have the right to withdraw from the experiment at any point during it.
Confidentiality of Results
This is another important point. Psychologists must keep all their data anonymous, and cannot even give a list of the people who took part in the experiment, unless you give your explicit permission that this is allowed.
Another point here is that participants of an experiment have the right to have their data destroyed. All you have to do is ask the psychologist, and he'll have to comply with this ethical guideline by destroying your data.
Deception
This point isn't so strong, because deception is actually allowed in psychological experiments. In fact, if participants in many studies weren't deceived as to what the true aim of the experiment is, the data would be inaccurate because they might figure out what was going on. If using deception, a psychologist will be observed by an independent advisor in order to make sure that the deception is justified and controlled. In fact, there must be valid scientific and medical justifications to use deception in the first place.
One common example of deception is calling participants to a study and having them wait in a lobby outside the study room. One by one they are called in to perform meaningless tasks, not aware that the actual study is taking place in the lobby, with hidden observers recording the participants' actions.
Debriefing
With the permitted use of deception comes a need for a debriefing. The final important ethical guideline is that after the study takes place, the participants must receive an explanation of exactly what the study was about, especially if there was deception involved. The golden rule with a debriefing is that participants should leave the study in the same condition that they entered it.
Well, there you have it. In the past, these ethical guidelines were not strictly, if at all, enforced. But these days, every psychologist has to stick to them.
