We conclude that until we conduct more field experiments that build a bridge between the lab and the naturally-occurring settings of interest we cannot begin to make strong conclusions empirically on the crucial question of generalizability from the lab to the field.
Under conservative generalizability (the inner, black circles), only the field experiment yields information about natural environments. As we become less conservative and the circles expand (to the outer, gray circles), both types of experiments yield potentially disjoint information about natural environments. Thus, they become complements in the production of knowledge. (p 17).
There is more on field and (versus) lab experiments here. The discussion has been going on in other fields as well (e.g. psychology).