[hollerith]

When your mom eats something that is bad for her and her brain can tell it is bad for her, then if that experience is repeated a lot, then every time it encounters that thing or even thinks about that thing, her brain will tend to cause a defensive reaction, which itself is unpleasant and can affect your mom's behavior. None of this need be conscious or deliberate.

[gruez]

I don't think gp is trying to imply that she's explicitly making it up, just that the phenomena is in her head. To take an absurd example, it's probably safe to say that electromagentic sensitivity doesn't actually exist (ie. radio waves aren't actually causing people pain/distress), even if sufferers aren't lying to others about their experiences.