As I have mentioned, I have been both an auditor and a preclear during my 7 years as a Scientologist, and I have substantial experience. I did a lot of auditing and received a lot of auditing. I certainly do not, at this point, have any desire to support the Church of Scientology, if anything, I have been accused of being biased against the cult. That being the case, I can answer those questions. You do not have to take my answers as being final, and indeed, in the best spirit of scientific research, you can make your own observations, although to really do that properly you would have to do two difficult things: acquire an e-meter, which tends to be expensive, and also learn how to audit, which is not as trivial a process as you might think. So it depends how important the research is to you. If it is just an amusing idea, to do as a lark, you might as well accept my own observations.

So, you are asking two questions. Does the auditors assumptions or prior knowledge of the subject influence how they interpret the readings? Do the subjects subconsciously attempt to move the dial to where they believe it should be?

My observation is that the only real assumption made by auditors (an assumption which is not entirely true) is that LRH technology is completely correct and always works. However the auditor does not make assumptions about the preclear. The auditor does not decide in advance what the preclear's aberrations are, or what kind of incidents the preclear may have experienced in the past which have resulted in his or her current mental state. The auditor merely asks questions and accepts the answers that the preclear gives. And as for the e-meter readings, an auditor simply observes them as accurately as possible. Readings have very specific meanings, so there is really no interpretation involved. You observe what the needle does. If the needle falls on a particular statement or question, that is a read. (The distance that the needle falls is also significant but we don't really have to get into all the details of how to read an e-meter.) If the needle rises, that is a different kind of read. If the needle floats, that has a certain meaning. If the needle does not react at all, that has a certain meaning. All of these are not open to various types of interpretation by the auditor, with the exception of the floating needle which looks the same as an ARC break needle (as I discussed in my now-deleted article on e-meters). So it is not really a matter of interpreting readings. Readings normally have only one interpretation (or in the case of the floating needle, two interpretations - and even in that case, the interpretation does not depend upon the auditor's assumptions or prior knowledge of the preclear, it depends upon observing the preclear in session).

As for the subjects subconsciously attempting to move the needle to where they think it should be, such an attempt would defeat the entire purpose of auditing. If the preclear believes that he or she already knows what their psychological or spiritual problems are, then the auditor and the e-meter are unnecessary. You seek auditing to help you to find out something about yourself that you do not already know. You want the e-meter to assist in this process. Auditing is generally expensive and/or difficult to obtain. This is something Chris Shelton refers to in his most recent Q&A video. He was a Scientologist for 27 years, but did not do any OT levels even though he very much wanted to do them. But staff members wind up being too busy. The Church of Scientology does not fully support the efforts of staff members to progress in their case state. And the public has to pay huge amounts of money, typically in the hundreds of thousands of dollars. Sometimes you can get a better deal if you are an auditor as well as a preclear and you can do a co-audit, but in practice this tends to be difficult to arrange, because auditing as it is normally done is not something that involves only the auditor and the preclear; there are usually at least two other people involved, the case supervisor and the examiner, and that is just the beginning since the Ethics Officer in some circumstances can get involved, the Director of Processing can get involved, etc. It's all very complicated. So when you have gone to all this trouble and/or expense to get auditing, you want to get the most out of it that you can, quite understandably. You do not want to blow it. And therefore, you allow the auditor to audit and you allow the e-meter to register whatever it is supposed to register. You are not trying to hijack the session, audit yourself, and make the e-meter read the way you think it should read. That would be completely ridiculous. I cannot imagine any preclear doing such a thing. But even if a preclear did do such a thing, I as an auditor would not be fooled. Every auditor is trained to spot the difference between a needle that falls because the preclear squeezes the cans - that can actually happen, not because the preclear is trying to fool the auditor but just as a nervous tic - and a needle that falls because it is giving a read. The needle falls in both cases, but not in exactly the same way. The read is smoother, the can squeeze is jerkier. So auditors know about these things.

But feel free to do your own experiments and arrive at your own conclusions. That is the true spirit of scientific enquiry.