96 Frank A. Russo, William Forde Thompson, & Lola L. Cuddy EFFECTS OF EMERGENT-LEVEL STRUCTURE ON MELODIC PROCESSING DIFFICULTY FRANK A. RUSSO words, does ease of processing depend in some manner Ryerson University, Toronto, Canada on emergent-level structure defined by theory? The current study investigates whether melodic processing WILLIAM FORDE THOMPSON difficulty varies with respect to music-theoretic descrip- Macquarie University, Sydney, Australia tions of emergent-level structure derived from the Implication-Realization (I-R) model (Narmour, 1990, LOLA L. CUDDY 1992). Queen’s University, Kingston, Canada Two leading cognitive approaches to understanding melodic complexity include information-theoretic and FOUR EXPERIMENTS ASSESSED THE INFLUENCE dynamic attending models. Information-theoretic mod- of emergent-level structure on melodic processing dif- els have focused on the development of coding systems ficulty. Emergent-level structure was manipulated (Cuddy, Cohen, & Mewhort, 1981; Deutsch, 1980; Leeu- across experiments and defined with reference to the wenberg, 1969; Restle, 1970; Simon, 1972). A hierarchi- Implication-Realization model of melodic expectancy cal melody with surface- and emergent-level structure (Narmour, 1990, 1992, 2000). Two measures of melodic can be described economically using nested codes that processing difficulty were used to assess the influence of exploit redundancies. The codes are assumed to capture emergent-level structure: serial-reconstruction and important aspects of mental representation, and empir- cohesion ratings. In the serial-reconstruction experi- ical studies have found that melodies with shorter codes ment (Experiment 1), reconstruction was more efficient are easier to process (Boltz & Jones, 1986; Deutsch & for melodies with simple emergent-level structure. In Feroe, 1981). Dynamic attending theory has focused on the cohesion experiments (Experiments 2-4), ratings the role of attention in the mental representations of were higher for melodies with simple emergent-level melody (Jones, 1987, 1993; Jones & Boltz, 1989). Inter- structure, and the advantage was generally greater in nal oscillators are presumed to entrain to levels of oscil- the presence of simple surface-level structure. Results latory structure that are defined by rhythmic and indicate that emergent-level structure as defined by the melodic accents (Large & Jones, 1999). The joint accent model can influence melodic processing difficulty. structure hypothesis posits that melodic processing is facilitated when rhythmic and melodic accents are in Received: November 22, 2014, accepted April 13, 2015. phase (Boltz & Jones, 1986; Jones, 1987; Jones & Pfor- dresher, 1997; Jones & Ralston, 1991). This approach Key words: melody, hierarchical structure, memory, has received extensive empirical support and provides cohesion, expectancy more flexibility than coding systems. The I-R model makes predictions regarding proces- sing difficulty and provides additional flexibility regard- HERE IS A RICH MUSIC-THEORETIC TRADITION ing the instantiation of hierarchical structure (Narmour, of describing hierarchical structure in music 1990, 1991, 2000). This is accomplished by considering (e.g., Forte, 1977; Lerdahl, 1988, 1989; Lerdahl T expectancy at different levels of structure. Two tones in & Jackendoff, 1983; Meyer, 1973; Narmour, 1983, 1990; sequence at any level of structure are said to be impli- Schenker, 1969, 1979). In the case of melody, this nor- cative, leading to bottom-up and top-down expectancies mally includes some description of the melodic surface for the next note to follow. Bottom-up expectancies and emergent structures that are composed of salient are Gestalt-like and proposed to be innate.1 Top-down events (see Narmour, 1983, for a useful review). From a cognitive perspective, an important question that 1 Narmour’s innate proposal is called into question by Pearce and arises from this work is whether listeners are sensitive Wiggins (2006, 2012) work on the IDyoM model, which demonstrates to these descriptions and whether they may relate in that the bottom-up expectancies can be simulated by corpus-based sta- some manner to melodic processing difficulty. In other tistical learning. Music Perception, VOLUME 33, ISSUE 1, PP. 96–109, ISSN 0730-7829, ELECTRONIC ISSN 1533-8312. © 2015 BY THE REGENTS OF THE UNIVERSITY OF CALIFORNIA ALL RIGHTS RESERVED. PLEASE DIRECT ALL REQUESTS FOR PERMISSION TO PHOTOCOPY OR REPRODUCE ARTICLE CONTENT THROUGH THE UNIVERSITY OF CALIFORNIA PRESS’S RIGHTS AND PERMISSIONS WEBSITE, HTTP://WWW.UCPRESSJOURNALS.COM/REPRINTINFO.ASP. DOI: 10.1525/MP.2015.33.1.96 Effects of emergent-level structure 97 expectancies are acquired through statistical learning (MMNm), suggesting that it is encoded preattentively (extra-opus) and through rule iteration (intra-opus). and automatically. Complexity at any given level of structure is thought Emergent-level structure was further clarified using to depend on the extent to which it fulfills expectancy two devices. First, under certain conditions, familiar (Narmour, 1990, 1992; also see Meyer, 1956, pp. 138- melodic patterns served as surface-level groups (e.g., 139). Consistent with this view, Rohrmeier and Cross major triad). Familiar patterns facilitate the identifica- (2013) recently reported that implicit learning of melo- tion of groups, which should support events rising to dies is impeded when surface-level events frequently the emergent level. Second, under certain conditions deny bottom-up expectancies described in the I-R surface-level groups were repeated under simple trans- model (Rohrmeier & Cross, 2013). Similarly, Loui position. Repetition should further clarify grouping (2012) found that statistical learning of an artificial structure and draw attention to the emergent level grammar is impaired after small intervals are removed (Deutsch & Feroe, 1981; Meyer, 1956; Margulis, 2013; from melodies (denial of a bottom-up principle of Narmour, 1990, 1992, 1999, 2000). expectancy referred to as pitch proximity). No empirical Meyer (1973, p. 53) states that ‘‘on the hierarchic level evidence exists to date regarding whether bottom-up where repetition is immediate, it [repetition] tends to principles of expectancy may influence melodic proces- separate events. But on the next level – where similar sing difficulty in hierarchically structured melodies. events are grouped together as part of some larger unit – In the current study, hierarchical structure was pri- repetition tends to create coherence.’’ Similarly, the I-R marily established through the manipulation of bottom- model states that all other things being equal, the extent up principles of expectancy. Note-to-note transitions of repetition at the surface will influence perceived com- within groups generally fulfilled expectancy, while plexity and that this complexity is inversely related to note-to-note transitions between groups denied expec- attention at the emergent level (Narmour, 2000, Table 1). tancy. The denials were achieved by following a small Hence, an immediate exact repetition of form (A0,A0)is interval (three semitones or less) with a large interval more expected and will emphasize emergent-level struc- (six semitones or greater). These expectancy denials ture more than an immediate near repetition of form occurred with temporal regularity so as to create (A0,A1), which in turn will be more expected and surface-level groups of regular size with the first note emphasize the emergent-level more than an immediate of each group rising to the emergent level (see Figure 1). contrast in form (A, B). See Figure 2 for examples of The type of expectancy denial implemented in this different types of surface-level repetition. study has been judged unexpected across a variety of Structure at the emergent level was categorically contexts (Cuddy & Lunney, 1995; Krumhansl, 1995; labeled as simple or complex. Simple emergent-level Schellenberg, 1996, 1997). Fujioka, Trainor, Ross, structure involved a sequence of small intervals moving Kakigi, and Pantev (2004) found that this type of in the same direction. This type of structure is referred denial elicits a magnetic type of mismatch negativity to as process in the I-R model and is considered highly expected (Narmour, 1989, 1990, 1999). Similar struc- tures have been described in other models as highly expected and even archetypal: inertia (Larson, 2012), good continuation (Meyer, 1956, 1973), step inertia (Huron, 2006; von Hippel, 2002) and direction (Margu- lis, 2005). Complex emergent-level structure also involved a sequence of small intervals but the direction of intervals varied resulting in a combination of struc- tures that is less expected. Two response measures were implemented to evaluate the effects of emergent-level structure on melodic proces- sing difficulty: serial reconstruction and perceived cohe- sion. In the serial reconstruction task adapted from the jigsaw puzzle procedure designed by Delie`ge and collea- gues (Delie`ge & Me´len, 1997; Delie`ge, Me´len, Stammers, FIGURE 1. Surface-level grouping is instantiated by realizing a denial of & Cross, 1996; also see Tillmann, Bigand, & Madurell, expectancy on every fourth note. Notes 1, 4 and 7 form a highly expected 1998), a melody is presented, after which participants are emergent-level structure referred to as a process. given randomly arranged segments from the melody and 98 Frank A. Russo, William Forde Thompson, & Lola L. Cuddy TABLE 1. Demographic Information Experiment