Does the behavior of a particle depend in part on every other experience the particle has had in the past? Physics has things that we can't figure out, and things that have to be observed in the aggregate, but it's much easier to perform multiple experiments with the same base conditions.

If we could clone the participants of a psychology experiment prior to the experiment, with their memories and personalities intact, we could possibly narrow the gap. Or maybe not! But that would be a fascinating finding! ;)