I saw a TV show where they had women do this and they were always totally off about where they stood in the line up. I think it was called 'how to look good naked" or something along those lines, it was about promoting women of all sizes taking care of themselves and feeling good about what they had to work with.
The episodes I saw women always put themselves in line 20+ Lbs over where they actually were!.

I love that show! It really shows how we see ourselves.

They even have them do things like recreate how they think they look with a virtual model or what size thighs they have and they always overshoot it.