Windsor effect
Overview
The Windsor effect is a psychological phenomenon where information passed on indirectly through a third party feels more trustworthy than information told to you directly by the person involved.
"Praising yourself" sounds like bragging, but hearing "Someone else was praising you" makes you genuinely happy. That is the Windsor effect. People tend to suspect a hidden interest behind a direct message, while information from a third party is less likely to draw that suspicion.
Question boxes and the Windsor effect
Why does anonymous feedback in a question box touch your heart? The Windsor effect is one reason. For example, when a friend tells you "I love your posts" to your face, you may suspect "Maybe they are just flattering me." But "I always look forward to your posts" arriving as an anonymous question takes the form of an evaluation from a third party with no stake in it.
In an anonymous question, there is little motive to flatter. The "lack of a stake" that comes with anonymity is behind the trustworthiness of anonymous feedback.
Using the Windsor effect, and a caution
One way to run a question box with the Windsor effect in mind is to share friendly questions and comments from your followers. Rather than saying "My question box is interesting" yourself, sharing a question where a sender says "Your answers are interesting" is more convincing in the eyes of a third party.
However, the Windsor effect can also apply to malicious words. You may end up taking it as "A third party with no stake in it went out of their way to criticize me, so it must be true."