Syntax in Music and Language: the Role of Cognitive Control
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Syntax in music and language: The role of cognitive control L. Robert Slevc ([email protected]) Department of Psychology, University of Maryland College Park, MD 20742 USA Jason G. Reitman ([email protected]) Wesleyan University Middletown, CT 06459 USA Brooke M. Okada ([email protected]) Department of Psychology, University of Maryland College Park, MD 20742 USA Abstract electrophysiological response characteristic of a violation of linguistic syntax (the left anterior negativity, or LAN) is The relationship between structural (or syntactic) processing in music and in language is not yet clear. Evidence indicating reduced when linguistic syntactic violations are paired with that these two processes are shared conflicts with other results a concurrent music-syntactic irregularity (Koelsch, Gunter, suggesting that they are largely distinct. These conflicting Wittfoth, & Sammler, 2005). Similarly, sung complex findings suggest that musical and linguistic processing may sentences are especially difficult to understand when critical share some, but not all, underlying processes, raising the regions are sung out-of-key (Fedorenko, Patel, Casasanto, question of what exactly those shared processes might be. Winawer, & Gibson, 2009). Two experiments tested the idea that one shared process is cognitive control by pairing manipulations of musical Other behavioral evidence comes from on-line sentence structure with the Stroop task, a standard test of cognitive processing paradigms, where readers’ slowed processing of control. Manipulations of harmonic expectancy, but not of temporary syntactic ambiguities is especially pronounced timbral expectancy, interacted with Stroop interference when the disambiguating word is paired with a harmonically effects, suggesting that cognitive control is at least one unexpected chord (Slevc, Rosenberg, & Patel, 2009; also specific process underlying shared syntactic processing in see Hoch, Poulin-Charronnat, & Tillmann, 2011, for related music and language. findings). More specifically, Slevc et al. (2009) relied on Keywords: cognitive control; music and language; musical garden path effects, where readers are slower to syntax comprehend the disambiguating word was in a sentence like “The scientist proved the hypothesis was false” compared to Introduction an unambiguous context like “The scientist proved that the Interest in the relationship between music and language has hypothesis was false.” This slowed processing presumably a long history, dating back at least to Darwin (1871). Over reflects the need to revise an initial syntactic interpretation the last several years, a more specific focus on the where the hypothesis was interpreted as the direct object of relationship between structural (or syntactic) processing in the verb proved rather than as the subject of an embedded music and language has received increasing attention (for sentence complement. This garden path effect was more recent reviews, see Patel, 2008; Slevc, 2012; Tillmann, pronounced when the disambiguating word (was) was 2012). This likely is due, at least in part, to an influential accompanied by a harmonically unexpected chord (but not proposal about the relationship between structural when accompanied by a chord of unexpected timbre). processing in language and music: Patel’s (2003) shared Importantly, such an interaction did not emerge for syntactic integration resource hypothesis (SSIRH; see also semantically unexpected words (e.g., pigs as a continuation Patel, 2008). The SSIRH proposes that music and language of “The mailman was afraid of…”) suggesting that the involve separate representations (e.g., nouns and verbs in interactive processes are specific to syntax. However, a language, tonal functions in music), but recruit a shared set more recent finding casts doubt on this last conclusion: the of cognitive resources that are required to integrate these same harmonic manipulations did lead to interactive effects separate representations into evolving sequences. when paired with sentences containing “semantic garden There is a growing body of evidence supporting the paths” such as “The old man went to the bank to withdraw SSIRH. Much of this evidence comes from experiments his net which was empty” (Perruchet & Poulin-Charronnat, using interference paradigms, where participants are 2013). Thus it seems that these interactive effects (and the simultaneously presented with both musical and linguistic shared integration resource of the SSIRH) may not be stimuli. In these paradigms, syntactic manipulations in both specific to syntactic processing per se. domains are crossed to look for interactive effects that In addition, some recent neuroimaging studies have not indicate shared processing (vs. additive effects, which found substantial overlap between neural regions implicated would indicate independent processes). For example, an in the processing of language and music (Fedorenko, Behr, 3414 & Kanwisher, 2011; Rogalsky, Rong, Saberi, & Hickok, One form of indirect evidence for a role of cognitive 2011). These studies compared a linguistic contrast control in musical syntax comes from neuroimaging (activation to intact sentences versus non-words or versus findings. Regions in the inferior frontal gyrus (including jabberwocky sentences) to a musical contrast (activation to Broca’s area) that are linked to cognitive control processes intact music versus scrambled music or versus silence), and (both generally and in language processing; e.g., Miller & found little evidence for shared regions implicated in both Cohen, 2001; Novick et al., 2010) have also been implicated contrasts. in neuroimaging studies of musical syntactic processing These conflicting findings raise the question: what kind of (albeit more bilaterally or even right lateralized; e.g., Maess, shared process links musical structural processing to some Koelsch, Gunter, & Friederici, 2001; Tillman, et al., 2006). aspects of linguistic processing (including syntactic errors, A second form of indirect evidence for a role of cognitive syntactic complexity, and both syntactic and semantic control in musical syntactic processing comes from garden paths), but not to other aspects such as the evidence that musical training is associated with advantages processing of semantically surprising words and the in cognitive control ability (Bialystok & DePape, 2009; difference between intact and scrambled sentences? One Pallesen et al., 2010) among other types of cognitive way to characterize this distinction is that the aspects of advantages (e.g., Schellenberg, 2006). A musician language processing that are related to musical structure advantage in cognitive control could plausibly result from require not only the processing of an unexpected element, the additional demands placed on cognitive control but also the resolution of conflict between this unexpected mechanisms from extensive musical training and practice, information and a current representation of an incrementally but only if those demands tax (and thus potentially constructed (and/or predicted) structure. The unrelated strengthen) cognitive control processes. aspects of language, in contrast, may not place demands on conflict resolution per se as there is no obvious way to Current experiments resolve a semantic anomaly or a scrambled sentence. The aim of the experiments reported here was to provide a This sort of conflict detection and resolution process is direct test of whether cognitive control mechanisms are termed cognitive control, referring broadly to the cognitive involved in musical syntactic processing (as has been processes that allow for the regulation of mental activity argued to be the case for linguistic syntactic processing). If required to resolve competing representations (see, e.g., cognitive control processes are, in fact, an important part of Miller & Cohen, 2001). Cognitive control processes have musical syntactic processing, less expected chords should been implicated in various aspects of language processing, impose relatively greater demands on cognitive control. including parsing of garden path sentences and semantic Assuming cognitive control is a limited-capacity resource, plausibility effects (see Novick, Trueswell, & Thompson- this should lead to a temporary reduction in the ability to Schill, 2010, for a recent review), and it is possible that the exercise cognitive control in other tasks. types of linguistic manipulations that interact with musical In order to measure demands on cognitive control, we structure are of this general type. By this account, studies turned to a prototypical cognitive control task: the Stroop finding interactive effects between musical structure and task (Stroop, 1935; see McLeod, 1991, for a review). In the language (be it linguistic syntax or non-syntactic situations standard Stroop task, participants must name the ink (or that require resolution between conflicting representations font) color of printed stimuli. These stimuli can be of three like semantic garden paths) might reveal simultaneous use types: congruent, where the printed word is the same as the of cognitive control resources. to-be-named ink color (e.g., the word “GREEN” printed in This account implies that musical syntactic processing–at green font), incongruent, where the printed word is a least as measured in the studies cited above–also relies on different color name than the two-be-named ink color (e.g., cognitive control mechanisms. Indeed, this is likely to be the word “BLUE” printed in