Interesting. However, those are attempting to replicate the results, and not the experiment; from my level of education and based on the abstracts, that sounds

Interesting. However, those are attempting to replicate the results, and not the experiment; from my level of education and based on the abstracts, that sounds more like "significant results" rather than "disproving results". The first abstract actually describes a theory that cannot be correct given the Rat Park experiment as described on Wikipedia, due to group PC (no new rats were supplied to that group). Or, rather, a theory that does not explain group PC.