Who came up with these signs?

When I first arrived in Poland I ran into some trouble straight away when I had to go to the toilet. I was confronted with images similar to those in the photo and I used my higher brain function to both logically try to figure this little puzzle out and subdue my urge to release. After what seemed like days and no native poles noticeably male or female needing to enter, I needed to bite the bullet myself. I had just seen and read the Da Vinci code and in this moment thought I was extremely clever for remembering the bit about the 'Sacred Feminine' symbol which was a triangle and represented a woman's hips and womb (the one in this photo is upside-down by the way). In my moment of revelation while confidently marching in to the opposite door I didn't even notice the lack of urinals and needless to say soon after there were a few shocked and red faces especially on my part.

I think these signs are unique to Poland but I have yet to find out why they are used or where they come from. If anyone knows who reads this please comment as it is one of those things that continue to niggle me especially on those occasions when I still find myself going into the wrong room (usually on a night out). Is it just me that finds this hard? Otherwise I hope I don't have a subconscious preference for women's' toilets and use this as an excuse!

I might as well talk about an experiment I done at uni since it's related, well kind of. I studied microbiology and one thing I remember was having to measure the amount of microorganisms, namely bacteria, in the air of the male and female toilets in the department. Hence we were measuring the cleanliness of each and guess which toilet was filthier? The women's'!!! Ha. All that time that women spend doing their hair, make-up and holding board meetings in there contaminates the air. Of course I realise the floor is a different story as men like to hit everything apart from the urinal but that is not part of this experiment and therefore irrelevant :)