Physics or psychology?

The physicist is telling me that it's a law:
a substance can only be affected
by what it can produce.
And so of course I'm wondering
if that might somehow be tied
to that psychological phenomenon I see so often,
in myself, and in others -- you know the one --
where the behaviors you find troublesome in others
are so often behaviors that you don't see in yourself
(though others see them, and are equally troubled);
the shadow that is cast beyond the curtain of unknowing.
the things that we assume motivate others
are so often the very things that motivate ourselves...

So then I have to ask:
would we even be affected by choices others make,
or things others say,
if we'd never thought of doing or saying them ourselves?