Abstract This work presents original results from a new experimental approach to Differential Object Marking (DOM) using customized Acceptability Judgment Tasks (AJTs) in varieties of Spanish (Iberian, Mexican, Peruvian, and River Plate) and Portuguese (Brazilian, European), together with data from Catalan varieties obtained with the same methodology, Differential object Marking in Romance: The third wave, 279–314. Berlin & Boston: de Gruyter). We show that AJTs can be used to produce a fine-grained picture of similarities and contrasts in the variation of Ibero-Romance DOM along well-established prominence scales, such as the Extended Animacy Hierarchy. We also test a series of predictions from the literature for each variety. Although we find clear evidence for scalar effects, we question the explanatory potential of a finite set of categories on prominence scales, and we argue that in order to explain DOM in the varieties under investigation, the nature of such scales needs to be better understood.