I wouldnt read too much into the idea of a psychological filter, its basically just a way of distancing yourself from and screening someones words
like if a mate of yours who liked and trusted said to you "I hate your guts" it would presumably be more hurtful than the words of a blind drunk tramp who you would know wasnt really talking to you anyway or someone who had some other agenda (a desire to hurt you or pull you down)
in some way I think (as in it seems to me) we "label" the communication of certain people as more or less valid or relevant than the communication of other people
somehow we choose how to categorise different people as being the givers of communication we will care more or less about- you might call it putting them in the "idiot" box... or the "guru" box depending on how you have value judged them and their communications with you.
Think of a time when someone you initially thought was ok said something stupid and you decide "ok actually they are just a dick", in this way, inside your head you devalue them, this devaluation process is "filtering".
at some point if somone persistently demonstrates they have an agenda to attack you psychologically and you catch them out, they have "played their hand" their FUTURE communications with you need to be clearly deliniated in your mind as agenda fuelled "noise" that needs to be dealt with but ultimately ignored.
hope this helps