Of course piqued by the @vwaehfpz statment “…since object permanence featured in a recent blog post…” I had to throw the term in the ChinWag search box. Got this pretty good link:
Not sure if that’s what they were referring to but dang sure delivers the intent, with bells on.
And using search here to find it feels karmically recursive in some weird fixed point, lambda calculus way. 
YMMV.