Example: I had been reading up on the Glycemic index, and decided to get the response curve of blood sugar level to glucose measured (there is a name for this test, which I have forgotten). How this works is you drink a bottle of highly concentrated glucose drink, and then have a series of blood samples taken over a period of several hours. My expectation, from what I had read, was that my body would over-compensate for all this glucose entering my system, my blood sugar levels would crash, and I would feel awful and depressed. And indeed over the course of the test I felt quite awful. When the results came back, of course, they showed my blood sugar level had responded in a perfectly normal way. But during the test, I believed.
Another example: I have developed a theory that autism might be measurable by patterns of eye saccades. In particular, a certain statistic would be different in a certain way. I couldn't get hold of numerical data to test this, but I found a few pictures of saccade patterns, and managed to convince myself that they showed the difference in this statistic that I was looking for. Well, by a somewhat circuitious route I later came to believe that that statistic would in fact be altered in the opposite direction. And looking at these pictures again, I found that now this looked to be true. Of course I am rather dubious of my new opinion, and will need actual numerical data -- which I should have known I would need all along.
There are other examples. Particularly, trying a range of psychopharmaceuticals and herbal remedies led me to experience all sorts of placebo effects.
So it seems to be quite an easy thing to fool myself. I'm sure most other people have this ability, and we all apply it to all sorts of things. It's a well documented effect, plenty of known examples where it occurs.
Can we teach people to recognize self deception?
I imagine a series of high-school science type experiments, but where the students are sometimes told to expect the right result and sometimes told to expect something different. And then they can repeat the experiment once told the correct results to expect. (I think it would be quite reasonable to incorporate the occasional such deception as a standard, ongoing feature of high-school and university science courses.)
Another approach, from "Alexander Technique". It is possible to think you are holding some particular posture, and that your limbs are positioned in certain ways, but when you (say) look in a mirror you find they are actually positioned quite differently. I found this happening to me especially with the angle my feet were pointing, but I expect it differs between people. So this is another way to demonstrate that you can be quite sure of something until you actually check it and find out you are wrong.
To take this idea further, and I can see no obvious contradictions to this, we could say:
"Self-deception is the origin of all sin."
This immediately seems a good framework for considering many of our current political problems, for example.
Orson Scott Card gives another good example here (see final paragraph).
This broader context would require a somewhat more general means of teaching. To tie it in to my earlier entry on horror and hope, such a lesson would involve humour ... I really need a term for what this form of humour is. Lets call it somewhat arbitrarily "gray humour". Not black humour, which exaggerates ill fortune, not comedy, which promises a happy ending, not tragedy, in which suffering has meaning. Somewhere in the middle, but also with distinct qualities (which I will need to pin down) ... Also not something that can be held at arm's length. hmm...