The diachronic development of Differential Object Marking in Spanish ditransitive constructions

Differential Object Marking (DOM) in Spanish synchronically depends on the referential features of the direct object, such as animacy and referentiality, and on the semantics of the verb. Recent corpus studies suggest that the diachronic development proceeds along the same features, which are ranked in scales, namely the Animacy Scale, the Referentiality Scale and the Affectedness Scale. The present paper investigates this development in ditran- sitive constructions from the 17th to the 20th century. Ditransitive constructions in Spanish are of particular interest since the literature assumes that the differential object marker a is often blocked by the co-occurrence of the case marker a for the indirect object. The paper focuses on the conditions that enhance or weaken this blocking effect. It investigates three types of constructions with a ditransitive verb: (i) constructions with indirect objects real- ized as a-marked full noun phrases, (ii) constructions with indirect objects as clitic pronouns, and (iii) constructions with non-overt indirect objects. The results clearly show that DOM is more frequent with (iii) and less frequent with (i). Thus the results support the observation that the co-occurrence of an a-marked indirect object (partly) blocks a-marking of the di- rect object to a certain extent. Furthermore, the results show for the first time that indirect objects realized as clitic pronouns without the marker a have a weaker blocking effect, but still a stronger one than constructions without overt indirect objects. In summary, the paper presents new and original evidence of the competition between arguments in a diachronic perspective