PT149 · S3 · Q21 In an experiment

Let's stop at the trigger and ask ourselves if we know anything ... were there any people that always guessed the next image would appear at the top? We don't really know. We know that most of them didn't guess that, since they were wrong most of the time. And the final sentence is giving us a counterfactual about what would have been true if they had all always guessed "next image will be on top". So given that we don't know anything about this trigger, it's hard to say we can derive a must be true of what would follow. If we assume that nobody was constantly guessing "next image on top", then this answer is just talking about a counterfactual. It's saying, "Yeah, nobody guessed X, but if they had guessed X, it wouldn't have been based on any pattern they believed they saw." How would we prove that counterfactual? How can we say in a hypothetical situation what someone would / wouldn't have believed they saw in the sequence? The contrapositive of this conditional rule is saying: if they were basing their they would not have guesses on a pattern → always guessed next they believed they saw image on top We know for a fact that all of the subjects were guessing based on a pattern they believed they saw. So according to this answer choice, none of them would have guessed "next image will appear on top". That's too strong. We know most of them weren't guessing "next image will appear on top" because most of the time they were wrong, but it's still possible that some of the subjects guessed "next image will appear on top". It's possible that some subjects guessed perfectly. The low accuracy of all the other subjects could lower the group's accuracy to where it's still true to say "the subjects guessed correctly less than half of the time". (as a desperation move, you might avoid guessing this tempting answer because Must Be True questions often put a very tempting but wrong answer non-coincidentally into the slot for choice (A). Given that this answer was conditional strength and in a famously trappy spot, we might convince ourselves we're safer choosing something farther down in the answer choices that also makes sense)

This answer is too strong because it's presented as a truism that goes beyond this experiment. We would only be able to comment on what sort of guessing would have had what sort of accuracy for this experiment. We can't extrapolate a rule that's applicable to other situations.

It's possible there was a predictable pattern someone could have reasonably believed occurred. Maybe it looked like it was doing "3 tops, 1 bottom, 3 tops, 1 bottom". Even if it didn't end up doing that exact pattern, it might have been close enough to that for us to say there was a predictable pattern that one could reasonably believe occurred. The fact that these people thought they saw patterns, but were largely wrong, doesn't make those patterns unreasonable ones to believe you saw.

Out of Scope: rational Too Strong: most rational Just because the subjects turned out to be wrong most of the time doesn't mean they were necessarily behaving irrationally. They thought they perceived a pattern. Making a guess based on a perceived pattern is pretty rational. We call that inductive reasoning. We certainly don't have any ammunition in this paragraph for deciding what the most rational strategy was here.