When I see the picture now I can just think "well it is both". I find it interesting that this changed over time.
The others are strangely enough just one interpretation and no other.
The abstract duck/rabbit variant is just a rabbit in this picture for me.
cowboy/Indian: Lady that looks away, nothing else. this is one of the interpretations when I original learned about this (in my mother language). I forgot the other option. Never heard of cowboy/indian; must be cultural thing.
face/mother: just a face, where is a mother o0
mouse: well yea I see why people also see a man, but c'mon really the mouse has much better matching than a man - in my view.
The first duck/rabbit picture is completely different from the other four sketches. It just made with much more quality and is actually ambiguous. The other ones are just way to much on or the other side and hence unambiguous.