Optional Madness Rules

So, when I was reading Unknown Armies, I could have sworn that I came across an optional rule that allowed you to resist some forms of madness better but be weaker against others depending on your background. I think that the rule was that you could flip the result of any madness check in the category in which you were more resistant, but you had an automatic and permanent notch in the instability column in the madness in which you were weak.

I remember one of the examples looking like this, though obviously it isn’t an exact copy:

Scientist (Unnatural/Unnatural): The scientist works within a rational framework of the universe, which allows him more resitance against the influence of the bizzarre and incomprehensible: he assumes that it fits within his framework. However, when something is truly impossible to understand, it undermines the foundations upon which he has built all of his knowledge.

The next few times I read the book this optional rule wasn’t there. Is this something that I keep missing, is it something I saw on the internet and associated with the book, or did I just make it up? Has anyone else ever heard of this rule?

I would appreciate any help.