You know I was only thinking about this (experiencial learning and danger) the other day.
Our elderly neighbour died recently and the house was unoccupied for sometime, which eventually lead to a problem with mice.
DH put a few traps down in a room normally not accessible by DS1, however a few days later DH had to do something in this room and DS1 went in with him, as soon as he saw the two traps he immediately picked them up and with a loud 'SNAP' had a mouse trap on each hand hanging off his fingers.
DS1 has a high pain threshold but definately felt them and was a little startled, anyways DH took them off and put them back telling DS1 'no touching' and thinking it would be fine 'once bitten, twice shy'.
What happened? Well you guessed it, DS1 immediately went over and picked them leading to exactly the same result as previously.
DH sorted him out and put them down again and couldn't believe his eyes as DS1 made it clear he was intent on exploring them further, leading to DH abandoning what he had to do and taking them both out of the room.
Although when relaying the story to me, I admit to having a little chuckle as I couldn't help but imagine both DH and DS1 as characters from the Lee Evans movie 'mousehunt'. It is scary to realise that without the ability to learn from his own experiences DS1 is going to have the potential to repeatedly put himself into harmful situations, even within our carefully risk assessed home environment.
I haven't though of anyway of improving this yet and as with so many things, I am hoping that it will get better as he gets older, but I would be interested in anything that has worked for others.