How can you thwart the sleeper effect? 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.
