Ah, also this sentence helped my understanding:

Teachers were instructed to treat silence as an incorrect answer and apply the next shock level to the student.

I imagine -- perhaps erroneously -- that I would have tried to obtain the verbal agreement of the learner before continuing. But, for example, this is because I know that continuous subject consent is required whereas this might not have been generally known or true in the early 60s.

Of course, I do see the pattern that this is probably such a case where everyone wants to rate themselves as above average (but they couldn't possibly all be). Still, I will humor my hero-bone by checking out the book and reading about the heroic exceptions, since those must be interesting.