I suspect "spam filter heuristics" also contribute to close mindedness. If something is repeated ad nauseam and the observer finds it false every time then they

I suspect "spam filter heuristics" also contribute to close mindedness. If something is repeated ad nauseam and the observer finds it false every time then they mentally downgrade the reliability to "known bullshit, not worth listening to". The process is agnostic to any objective truth and could apply to stubborn flat-earthers taking "against intuition and the ability to easily comprehend like a flat map" as false.