How does Montresor use reverse psychology on Fortunato?

Montresor uses reverse psychology to trick Fortunado into going into the crypt with him by suggesting that he will have someone else look at the wine and by asking him if he is sick once he gets there.

Reverse psychology is the act of tricking someone into doing something by telling them not to.  Montresor uses this technique twice.  First he tells Fortunato that he will have someone else look at the Amontillado wine cask if he doesn’t.  Then he brings attention to his cough and tells him to leave.

Montresor’s ruse to get Fortunato into the crypt is asking him to look at a special cask of Amontillado wine.  He tells Fortunato that if he does not look at the wine, he will get someone else to do it instead.

“As you are engaged, I am on my way to Luchesi. If any one has a critical turn it is he. He will tell me—”

“Luchesi cannot tell Amontillado from Sherry.”

“And yet some fools will have it that his taste is a match for your own.”

Montresor knows that Fortunato will never give up the chance to show off his wine knowledge.  By suggesting that he will show the wine to Luchesi, he is pretty much guaranteeing that Fortunato will come to see the wine.  He knows Fortunato very well.

Montresor uses the trick again to pretend that he wants Fortunato to go back once they are actually in the crypt.

“How long have you had that cough?”…

“It is nothing,” he said, at last.

“Come,” I said, with decision, “we will go back; your health is precious.You are rich, respected, admired, beloved; you are happy, as once I was. You are a man to be missed. For me it is no matter. ..."

This is actually pretty brilliant.  Fortunato is drunk, and does not see through the ruse.  He just insists that he is fine, and they continue.  By the time Fortunato figures out that Montresor actually does not care about his health and in fact wants to kill him it is too late!

The fact that Montresor is able to use reverse psychology so effectively shows that he is a good judge of character.  That he can lie so convincingly is further proof that he is a psychopath.  He wants revenge, and he will stop at nothing to get it.