Sleeper Effect
Why Propaganda works
In our memories, the source of the argument fades faster than the argument. In other words, your brain quickly forgets where the information came from (e.g. from the department of propaganda). Meanwhile, the message itself (i.e., war is necessary and noble) fades only slowly or even endures. Therefore, any knowledge that stems from an untrustworthy source gains credibility over time. The discrediting force melts away faster than the message does.
How to avoid?
First, don’t accept any unsolicited advice, even if it seems well meant. Doing so, you protect yourself to a certain degree from manipulation.
Second, avoid ad-contaminated sources like the plague. How fortunate we are that books are (still) ad-free!
Third, try to remember the source of every argument you encounter. Whose opinions are these? And why do they think that way?
Probe the issue like an investigator would: cui bono? Who benefits? Admittedly, this is a lot of work and will slow down your decision- making. But it will also refine it.