When you interact with someone, you may think, I will do this, so that they will do that, or think such-and-such, or feel thus-and-so; but what is actually going on for them may bear no resemblance to the model of them that you have in your head. If your model is wrong at the meta-level -- you are wrong about how people work -- then you will either notice that you have difficulty dealing with people at all, or not notice that the problem is with you and get resentful at everyone else for not behaving as you expect them to.

Here, Mrs. B.F. Skinner imagines that she is reinforcing the behaviour that she desires, of eating spinach, by providing the reinforcer, ice-cream. Or is she really punishing the consumption of ice-cream by associating it with spinach? Or associating herself with an unpleasant situation? Or any number of other possibilities.

Sure thing. For me, it was the sudden realization that I had made assumptions from the very start of reading it, and that I had ranked certain outcomes far lower than the problem -- taken in isolation -- would justify.

When I read it, I immediately thought, "Okay, rewarding a kid for eating spinach, same ol' same ol' ..."; then when I got to the end, I -- very quickly -- absorbed the insight that, in order for the process not to result in the child hating the mother, certain conditions have to hold, which are probably worthy of probing in depth.

I know all of this may sound obvious, but I really had an aha!/gotcha! moment on that one.