Do Yellow Letters really NEED to be yellow?

[Audrick Brown IV]

Hey BP community! I'm Audrick and I would qualify as a newbie as I have not completed any deals yet. I'm in the intensive learning phase and I'm trying to understand as much as possible as quickly as possible so that I can move to the action phase. In regards to generating leads, specifically via direct mailers, I understand there are several ways to go about it (postcards, letters, etc.). I keep hearing about these "Yellow Letters" I have actually received one from an investor in my area and it was literally was yellow. I was wondering...is there some proven science behind using letters printed on yellow paper? Or is this just an industry specific thing that started somewhere back in time and has just been passed down from generations of investors. Is there something about the yellow color which makes more it effective than say a white paper, brown paper or blue (my personal favorite)? I know this is a really specific question. But, I'm trying to think of creative ways to make my mailers a bit more effective than the generic mailers already in the marketplace. So I didn't want to invest resources (time, money, energy) into something that has previously been vetted. 

Thanks for any insight you provide in your response.