I never considered the 3D aspect; but it makes perfect sense.*
  For me, I find that as long as the LOCATION is more or less the
  same, I can find something again.* With messy piles, I like the
  face that little pieces of everything are "sticking out"; and
  with the clues of location plus a piece of the actual item
  sticking out, I can retrieve things very quickly.
  [1][IMG]
  [2]KENNETH UDUT
  3:13 AM
  +[3]Ulrich Baer In thinking about it, I'd say that our brains
  may store best in a slightly less than 3D fashion; perhaps 2.5D
  or 2.75D: Think about the wireframe of a 3D cube; we can see
  every point except the one that is furthest in the back; that's
  a blind spot (the "180 degrees behind") that we have the
  greatest trouble with conceptualizing. In other words, things
  "disappear" if we don't see them.* A human weakness I think. But
  we see and remember much of the way around things; certainly
  much more than 2D.* We also have Time on our side; "when" we
  last saw something.* A benefit of our Time travelling brain.* It
  might not be linear time; but certainly we can remember
  circumstances and situations that happened around the time we
  last saw something, helping in our retrieval of the object.

References

  Visible links
  1. https://plus.google.com/u/0/116220525110856958463
  2. https://plus.google.com/u/0/116220525110856958463
  3. https://plus.google.com/111459097911372068059