The biggest of blindspots spring up when our minds form opinions about our minds. Here the question is: when we change our opinions, are we aware of that fact? The obvious answer is yes; the true answer is hinted at by Goethals and  Reckman’s 1973 experiment:

High school students were asked their opinions on a variety of social issues, including on how children should be bussed to school and whether it would help with racial integration. […]

A couple of weeks later the students were invited back for a further discussion on the bussing issue. This time, though, they were split into two groups, one that was pro- and one anti- the bussing issue. […]

The two groups had separate discussions about the bussing issue, but amongst their number had been planted an experimental confederate. The confederate was armed with a series of highly persuasive arguments designed to change the participant's minds on the issue. Experimenters wanted to turn the pro- group into an anti- group and the anti- group into a pro-group.

The confederates turned out to be extremely persuasive (and/or the students were easy to sway!) and the two groups were successfully turned around.[…]

But what happened when they were asked about this change of opinion?

When compared to a control group who were not involved in the further discussion, neither of the experimentally manipulated groups could accurately remember their original position. […]

First those who were anti-bussing originally recalled their pre-manipulation position as being much more pro-bussing than it actually was. Even more impressively, those who were originally pro-bussing thought they were actually anti-bussing before the experiment. Their recall of their previous position had completely turned around.

 I’ve been thinking on my own opinions, and have now identified a bunch of opinions that changed without me realizing them (mainly in politics). So take a moment today to write down your own opinions, and store them somewhere you’ll rediscover them in a few years. Try and include precise probabilities about your opinions, as mere words can be reinterpreted later on.

And be aware that, in thought experiments involving yourself as a youth, you’ll have even less in common with yourself than you think.