Caligula effect
Overview
The Caligula effect is a psychological phenomenon where you feel stronger interest in or desire for something precisely because it has been forbidden or restricted. The name comes from the 1980 film "Caligula": it was banned from screening in some areas, which only got people talking about it more, and audiences flocked to see it.
In psychology, it's explained as a type of "psychological reactance." When people's freedom is restricted, they become motivated to win that freedom back. This pushback is one reason why the more you hear "no," the stronger your "I want to" becomes.
Question boxes and the Caligula effect
The Caligula effect shows up clearly in a question box when you announce, "I won't answer questions on this topic." When the person answering refuses questions in a particular genre, questions in that genre can actually increase. Write "No love-life questions, please," and love-life questions tend to pile up. That's because the ban stirs up curiosity.
Writing "Please don't ask about X" in your profile works the same way. Maybe nobody would have cared if you hadn't written it, but spelling it out as off-limits tends to draw more attention to that topic.
Turning the Caligula effect to your advantage
If you understand the Caligula effect, you can use it in how you run your question box. For questions you don't want to answer, quietly skipping them works better than "banning" them. Announcing a ban just triggers the Caligula effect and is unlikely to work as a deterrent.
On the other hand, you can also use the Caligula effect when you want more questions. If you give an answer with a hint of mystery, like "I might not be able to answer this one...," it stirs your followers' curiosity and makes follow-up questions more likely. But if you overdo it, people may see it as "teasing" and you can lose their trust, so getting the balance right matters.