This is a topic I was meaning to write a post about for some time. I encountered this topic while doing some social psychology reading last year, and it touches upon a lot of other posts I've written, having to do with decision-making and persuasion. It touches on the huge issue of bias which appears in so much of the medical and health literature.
Here is what some of the social psychology research has to say on this:
1) If someone already agrees on an issue, then a one-sided appeal is most effective. So, for example, if I happen to recommend a particular brand of toothpaste, or a particular political candidate, and I simply give a list of reasons why my particular recommendation is best, then I am usually "preaching to the converted." Perhaps more people will go out to buy that toothpaste brand, or vote for that candidate, but they would mostly be people who would have made those choices anyway. The only others who would be most persuaded by my advice would be those who do not have a strong personal investment or attachment to the issue.
2) If people are already aware of opposing arguments, a two-sided presentation is more persuasive and enduring. And if people disagree with a certain issue, a two-sided presentation is more persuasive to change their minds. People are likely to dismiss as biased a one-sided presentation which disagrees with their point of view, even if the presentation contains accurate and well-organized information. This is one of my complaints about various types of media and documentary styles: sometimes there is an overt left-wing or right-wing political bias that is immediately apparent, particularly to a person holding the opposing stance. I can think of numerous examples in local and international newspapers and television. The information from such media or documentary presentations would therefore have little educational or persuasive impact except with individuals who probably agree with the information and the point of view in advance. The strongest documentary or journalistic style has to be one which presents both sides of a debate, otherwise it is probably almost worthless to effect meaningful change--in fact it could entrench the points of view of opposing camps.
It has also been found that if people are already committed to a certain belief or position, than a mild attack or challenge of this position causes people to strengthen their initial position. Ineffective persuasion may "inoculate" people attitudinally, causing them to be more committed to their initial positions. In an educational sense, children could be "inoculated" against negative persuasion, such as from television ads or peer pressure to smoke, etc. by exploring, analyzing, and discussing such persuasive tactics, with parents or teachers.
However, such "inoculation" may be an instrument of attitudinal entrenchment and stubbornness: a person who has anticipated arguments against his or her committed position is more likely to hold that position more tenaciously. Or an individual who has been taught a delusional belief system may have been taught the various challenges to the belief system to expect: this may "inoculate" the person against challenging this belief system, and cause the delusions to become more entrenched.
An adversarial justice system reminds me to some degree of an efficient process, from a psychological point of view, to seek the least biased truth. However, the problem here is that both sides "inoculate" themselves against the evidence presented by the other. The opposing camps do not seek "resolution"--they seek to win, which is quite different. Also, the prosecution and the defense do not EACH present a balanced analysis of pro & con regarding their cases. There is information possibly withheld--the defense may truly know the guilt of the accused, yet this may not be shared openly in court. Presumably the prosecution would not prosecute if the innocence of the accused was known for sure.
Here are some applications of these ideas, which I think are relevant in psychiatry:
1) Depression, anxiety, and other types of mental illness, tend to feature entrenched thinking. Thoughts which are very negative, hostile, or pessimistic--about self, world, or future--may have been consolidated over a period of years or decades, often reinforced by negative experiences. In this setting, one-sided optimistic advice--even if accurate-- could be very counterproductive. It could further entrench the depressive cognitive stance. Standard "Burns style" cognitive therapy can also be excessively "rosy", in my opinion, and may be very ineffective for similar reasons. I think of the smiling picture of the author on the cover of a cognitive therapy workbook as an instant turn-off (for many) which would understandably strengthen the consolidation of many chronic depressive thoughts.
But I do think that a cognitive therapy approach could be very helpful, provided it includes the depressive or negative thinking in an honest, thorough, systematic debate or dialectic. That is, the work has to involve "two-sided argument".
2) In medical literature, there is a great deal of bias going on. Many of my previous postings have been about this. On other internet sites, there are various points of view, some of which are quite extreme. Those sites which are invariably about "pharmaceutical industry bias", etc. I think are actually quite ineffectual, if they merely are covering the same theme, over and over again. They are likely to be sites which are "preaching to the converted", and are likely to be viewed as themselves biased or extreme by someone looking for balanced advice. They may cause individuals with an already biased point of view to unreasonably entrench their positions further.
Also, I suspect the authors of sites like this, may themselves have become quite biased. If their site has repeatedly criticized the inadequacy of the research data about some drug intended to treat depression or bipolar disorder, etc., they may be less likely to consider or publish contrary evidence that the drug actually works. Once we commit ourselves to a position, we all have a tendency to cling to that position, even when evidence should sway us.
On the other hand, if there is a site which consistently gives medication advice of one sort or the other, I think it is unlikely to change very many opinions on this issue, except among those who are already trying out different medications.
So, in my opinion, it is a healthy practice when analyzing issues, including health care decisions, to carefully consider both sides of an argument. If the issue has to do with a treatment, including a medication, a style of psychotherapy, an alternative health care modality, or of doing nothing at all, then I encourage the habit of analyzing the evidence in two ways:
1) gather all evidence which supports the modality
2) gather all evidence which opposes it
Then I encourage a weighing, and a synthesis, of these points of view, before making a decision.
I think that this is the most reliable way to minimize biases. If such a system is applied to one's own attitudes, thoughts, values, and behaviours, I think it is the most effective to promote change and growth.
Myers, David. Social Psychology, fourth edition. New York: McGraw-Hill; 1993. p. 275; 294-297.