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.
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.