Are complex function words processed as semantically empty strings? a reading time and ERP study of collocational complex prepositions

Collocational complex prepositions (CCPs, e.g., in the hands of) are prefabricated strings of words that play a prepositional role in natural language. Typically, CCPs are formed by a first preposition (P1) followed by a content word (N1) and a second, final preposition (P2) (in the - P1 - hands - N1 - of - P2). Despite their default structure stored in semantic memory, some CCPs allow internal modification (e.g., adjective insertion). In this study, two experiments tested the comprehension of CCPs in which we modified their default structure inserting an adjective before the noun. This modification preserved the semantic well-formedness of the string. The self-paced reading time study (Experiment 1) showed that readers took significantly longer to read the CCP constituents after the inserted adjective (N1 and P2). The ERP (Experiment 2) showed a smaller N400 response to the noun when preceded by the adjective, suggesting that the insertion did not disrupt the on-line processing of the CCP. Critically, the adjective insertion increased the processing load of the prepositional phrase introduced by the CCP, as evidenced by a LAN in response to the complement noun (N2). Overall, these findings showed that processing CCPs was not disrupted by insertions despite their predefined default word order. Rather, their interpretation was semantically enriched, correlating with an increase in the processing load when the CCP was integrated with the complement noun.