I have noticed that at a certain point (some) children seek solitude to poop. It seems to happen overnight- one day the child is perfectly content filling his diaper in the living room, surrounded by his brothers, while playing with his cars. The next day he's hiding under the bed or simply going into the next room to do his business.
I realize not all toddlers do this- one of my three boys never did this (and interestingly enough, continued to refuse to acknowledge his urge to move his bowels and continued to poop his pants until...well, when it's been 5 years without incident we'll say it's over, but that's an issue I've discussed in another post) I've also noticed that it doesn't coincide with a readiness to use the potty. Hiding to poop seems to occur at least several months before pooping on the potty is an achievable goal.
I'm interested to know what kind of cognitive milestone this behavior signals. Also, I'd like to know if my current approach- which is to attempt to intercept the disappearing acts and redirect to the potty in lieu of a lonely closet, or if reasonable, to put the potty in the preferred hiding spot- is the best method in light of whatever developmental change is occurring?