Music and (natural and artificial) language processing. Two psycholinguistic studies

The present thesis consists of two psycholinguistic studies investigating the interplay between language and music from two different perspectives. Study One focuses on the relation between musical harmony and natural language, by taking its premises from the Shared Syntactic Integration Resource Hypothesis (SSIRH; Patel, 2003a), that posits an interference between the processing of syntax in the two domains. The study aims to extend this hypothesis, by investigating the role of linguistic syntactic complexity, in musicians and non-musicians. In a Self-Paced Reading Task (SPRT), 64 subjects were simultaneously presented with syntactically correct/incorrect Italian sentences and chord sequences. Incorrect sequences contained harmonical violations (out-of-tonality chords). Linguistic syntactic violations affected local and non-local dependency in three agreement configurations, giving rise to different gradients of syntactic complexity. As a result, significantly longer reading times were found in correspondence to double violations (linguistic and musical), reflecting interference between the processing of syntax in the two domains, and thus confirming the main prediction of the SSIRH. Given the absence of a group effect, this result was generalized to both musicians and non-musicians, pointing to the universality of the finding. Yet, no effect of linguistic syntactic complexity was found. This was probably due to the relative ease of the linguistic conditions, in relation to the kind of subjects tested (typically developed, adult native speakers of Italian). The same subjects were tested in Study Two, an explorative study on the relation between musical rhythm and artificial language. By means of a modified Simon Task, it aims to investigate whether (a variant of) the Tresillo rhythm facilitates the processing of specific components of the Fibonacci grammar (belonging to the Lindenmayer System), and whether group effects emerge. These components are either deterministic (determined by the rules of the grammar and learnt sequentially, in statistical terms), such as First-Law Points and Second-Law Points, and non-deterministic (not determined by the rules of the grammar and acquired hierarchically), such as K-points, and the Sequence [011 011 01]. As a result, both groups exhibited significantly shorter reaction times to both deterministic and non-deterministic components, when they were presented with rhythm. This was taken to reflect a facilitation effect played by the Tresillo on both sequential and hierarchical processing, which was found to be even stronger for non-deterministic components. This result is in line with previous evidence coming from non-musical studies on sequential and hierarchical learning in the Fibonacci grammar (Vender et al., 2019, 2020). The finding that also non-musicians were sensitive to rhythm is in line with research demonstrating that sensitivity to rhythm is universal, and independent of specific training (Phillips-Silver & Trainor, 2005). Secondly, musicians were significantly faster than non-musicians in processing the Sequence, both in presence and absence of the Tresillo. While musicians’ superior performance in the first condition can be explained by musical expertise, their better performance in absence of rhythm is quite remarkable and surprising and might be related to information-processing strategies allowing the grouping of smaller units into larger ones. To conclude, the musical element caused interference with natural language in Study One, where concurrent linguistic and musical violations led to high processing costs, but it played a facilitation role in Study Two, as rhythm facilitated the processing of structures of the artificial grammar that can be overlapped to it. This highlights the centrality of the experimental task in the comparative study of language and music and shows how multi-faceted the topic can be, even within the same discipline.