My understanding of #3 is that it comes from a place of insecurity. Someone secure in their own intelligence, or at least of their own self-worth, will either ignore the unknown word/phrase/idea, ask about it, or look it up.
So from the inside, #3 feels something like: “Look, I know you’re smart, but you don’t have to rub it in, okay? I mean, just ‘cause I don’t know what ‘selective pressures in tribal mechanics’ are doesn’t make me stupid.”
My guess is that it feels as though the other person is using a higher level vocabulary on purpose, rather than incidentally; kind of the like the opposite of the fundamental attribution error. Instead of generalizing situation-specific behavior to personality (i.e. “Oh, he’s not trying to make me feel stupid, that’s just how he talks”), people assume that personality-specific behavior is situational (i.e. “he’s talking like that just to confuse me”).
Also, I think a lot of the reaction you’re going to get out of someone when using a word or idea they don’t know is going to depend upon your nonverbal signals. Are you saying it like you assume that they know it? I’ve had professors who talk about really complex subjects I didn’t fully understand as though they were obvious, and that tended to make me feel dumb. I doubt they were doing it on purpose—to them it was obvious—but by paying a little bit more attention to the inferential distance between the two of us, they could have moderated their tones and body language a bit to convey something a little less disdainful, even if the disdain itself was accidental.
Lastly, when it comes to communication I tend to favor the direct approach. If at any point I think the other person doesn’t understand what I’m saying, I try to back up and explain it better. Sometimes I just flat-out ask if they understood, and if not, try to explain it, all while emphasizing that it isn’t a word/phrase/idea that I (or anyone) would expect them to know.
True or not, the above strategy has been effective for me in reducing confrontation when the scenario you’re describing happens.
“Instead of generalizing situation-specific behavior to personality (i.e. “Oh, he’s not trying to make me feel stupid, that’s just how he talks”), people assume that personality-specific behavior is situational (i.e. “he’s talking like that just to confuse me”).”
Those aren’t really mutually exclusive. “Talking like that just to confuse his listeners is just how he talks”. It could be an attribution not of any specific malice, but generalized snootiness.