Question: I was reading this [article](http://www.riagenic.com/archives/526) about Metro UI designs, and I was struck by this statement:

> 
> Example, if you look under the hood of a new car, you will see areas
>  colored yellow whereas the rest is the same color of the engine etc.
>  Car manufacturers do this on purpose, they want you to touch yellow
>  yourself but if it is not yellow and you are not mechanically minded –
>  leave alone.
> 
> 
> 

The author recommends using a color like Yellow as the **secondary color** as a means to draw people’s attention to the fact "I’m ok if you touch this, you won’t break anything if you do" thinking .I am a little unsure about this mentality that if you see something which is marked a different color other than the primary or background color,you would immediately mark it as a safe.

What are your views on it?

Answer: 
As the original author, i'll add my reasons:

It has to do with the fact pattern recognition is a built in component within humans, once we identify a familiar pattern it then becomes easier to seed.

The thing is, most users don't turn up to the average software as UX virgins? that is to say they aren't using a computer for the first time (some solutions are excluded of course). Typically the mainstream UX out there is often a horrible or confusing experience, all the primary / secondary color selection does is encourage that the user pick-up on the differences between chrome colors and input colors. Input colors = good!

It has a bit to do with extraneous cognitive load meets gestalt's laws of organisation.
Color-coding is ages-old and nothing revolutionary. It's present almost everywhere in technology: from peripheral connectors to input devices to wiring to the aforementioned cars.

Traditional rules for color-coding are 1) all these go together and 2) touch these things and don't touch those at all, both of which we already follow by styling active & inactive elements differently. Meanwhile, the article suggests applying colors as "touch these without reservations and expect something more dangerous to happen if you touch those", which makes no sense at all since potentially damaging controls shouldn't be exposed to the end-user to begin with.