Dimensions of Specificity in Musical Memory: Evidence from Metrical Restoration
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Dimensions of specificity in musical memory: Evidence from metrical restoration Sarah C. Creel ([email protected]) University of California, San Diego, Department of Cognitive Science La Jolla, CA 92093-0515 Abstract On first glance, a simple answer to both questions is degree How is musical memory organized? While classic studies of of similarity: listeners generalize to similar musical patterns, music perception appealed to schematic or symbolic and maintain specific representations of less-similar knowledge structures, recent work suggests that listeners form patterns. However, determining equivalent degrees of highly-detailed auditory representations of music. Studies of similarity on varied dimensions is not trivial, as perceivers’ metrical restoration—memory fill-in of the “beat” of a use of dimensions can change depending on task and metrically-ambiguous melody—suggest some organizing attentional factors (Nosofsky, 1986). That is, we do not dimensions in musical memory. However, many potential know what weights listeners assign to different dimensions dimensions remain unexplored. The current study looked for effects of mode (major vs. minor)—a substantial organizing in musical memory. Further, some dimensions may be force in Western music—and timbre (what instrument is processed integrally, such that their combined effect is not a playing) on metrical restoration. Both mode and timbre can simple sum of their individual effects. The current study signify particular musical styles. In Experiment 1, listeners aims to explore the relative strength of various auditory- showed timbre specificity in metrical restoration, but not musical properties on metrical restoration, providing mode specificity. However, in Experiment 2, when timbres insights into similarity-based organization in musical were extremely unique (one per melody), restoration effects memory. were not observed, suggesting that too much variability leads to diffuse representations which are too weak to support metrical restoration. Implications for the nature of musical !"#$ memory are discussed. &'()*+" Keywords: perceptual restoration, meter, music perception, metrical restoration ,)-.'$." Introduction Recent research suggests that listeners form rich, detailed !""#"""#"""$""#""#" !""#"""#""$""#""#" !"""#""#""$"""#"""#" !""#"""#"""$""#""#" !%" representations of perceptual information. These details later facilitate recognition (Creel, Aslin, & Tanenhaus, 2008; Goldinger, 1998; Gjerdingen & Perrott, 2008; Krumhansl, !%#$ 2010; Schellenberg et al., 1999) and allow fill-in of &'()*+" ambiguous or absent information (Creel, 2011, 2012; Samuel, 1981). In music particularly, Creel (2011, 2012) has shown that listeners who hear particular metrical (or ,)-.'$." harmonic) information with a melody will later, upon hearing the melody alone, fill in the missing contextual information (harmony or meter) previously heard with that !"#""$""#""$""#" !"#""$""#""$""#" !"#""$""""#"""$""#" !"#""$"#""$"#" !%" melody. These findings are interesting in a number of respects. First, meter is a property previously thought to be largely signal-driven, with listeners extracting metrical regularities Figure 1. First four measures of a melody, in (a) major key via statistical analysis of the signal itself. Creel’s work with 6/8 metrical context; (b) minor key with 3/4 metrical suggests that memory influences meter perception. Second, context. Metrical grids indicate perceived emphasis in each these findings suggest that similarity-based organization of meter: large X’s denote strong beats, small x’s weaker beats, detailed auditory-temporal memories can support and .’s indicate the subdivision of each beat. Beat knowledge of distinct genres, such as different musical subdivisions are identical in duration in both versions. styles or different languages. Yet many questions remain. What factors allow listeners Known influences on metrical restoration to keep particular musical patterns distinct in memory— Previous work in my lab (Creel, 2011, 2012) has examined what keeps them from bleeding together? Inversely, what some factors in memory restoration of meter. In those factors allow listeners to generalize metrical information? experiments, as well as the new experiments described here, 2106 I exploit the 3/4 – 6/8 ambiguity, a musical “ambiguous metrical restoration for new melodies with those motifs figure.” Certain musical passages with repeating series of 6 (Experiment 5). sub-beats can be interpreted as being in 3/4 meter (beats Interestingly, the magnitude of the metrical restoration alternating evenly with sub-beats, X . x . x .) or in 6/8 meter effects in the 2011 study was much larger than the effect in (each beat is followed by two sub-beats: X . x . ). Figure 1 Creel (2012). Though there were a number of differences shows examples of each meter. between the two sets of studies, one possibility is that the In my experiments, each listener heard a set of 8-12 denser similarity structure of the melodies in the second melodies. Half were presented in a musical context paper led to greater generalization, but, conversely, less suggesting 3/4, and half in a context suggesting 6/8. individuation. However, it is not clear which one (or more) Melodies were constructed to fit either metrical pattern, of the unique properties of the melodies in the 2011 paper allowing a carefully counterbalanced design where, across generated such strong restoration effects: rate, timbre, mode, listeners, each melody was heard in each meter equally rhythmic patterns. Do all dimensions of variation contribute often (Table 1). A listener heard each melody multiple times additively to specificity/individuation in memory, or is one during an exposure phase. Next, all listeners heard each particular factor the “smoking gun”? melody without its meter-implying context, followed by probe drumbeats in either 3/4 or 6/8. They were asked to Unknown effects on metrical restoration rate how well the drumbeats fit with the preceding melody. As seen in Creel (2011, 2012), timbre and motif content The question was whether listeners would provide higher seem to be integral to musical memory. That is, metrical ratings for the drumbeats (meters) that matched the contexts restoration shows timbre specificity and motif specificity. that they had previously heard. However, numerous dimensions of substantial music- theoretical importance remain untested. First, is there mode Table 1: Example conditions in a metrical restoration specificity? Mode, the particular pitch collection used in a experiment. If listeners restore melodies’ metrical contexts, musical piece, may be a signature of musical style: in then Listener 1 should provide higher probe ratings to the Western music, the most common modes are major and shaded probe trials, and Listener 2 should provide higher minor. Other musical styles and cultures are characterized probe ratings to the unshaded probe trials. by yet other pitch collections (e.g. Castellano et al., 1984). Mode also contributes to emotional processing: Western Exposure phase Test phase listeners associate the major mode with happiness, and the Mel- minor mode with sadness (e.g. Hunter et al., 2008). Listener 1 Listener 2 All listeners ody A second factor not previously examined is rate—the melody alone melody alone speed at which a musical piece is executed. Do listeners 1 3/4 context 6/8 context + 3/4 probe + 6/8 probe store melodies rate-specifically? melody alone melody alone Finally, the role of timbre bears further exploration. Is 2 3/4 context 6/8 context + 3/4 probe + 6/8 probe timbre simply one of many cues that differentiate music in melody alone melody alone memory? If hearing melodies in two timbres allows listeners 3 6/8 context 3/4 context + 3/4 probe + 6/8 probe to keep metrical patterns distinct, then does hearing melody alone melody alone melodies in even more timbres create even more distinct 4 6/8 context 3/4 context + 3/4 probe + 6/8 probe metrical representations? In Creel (2011, Experiment 2), listeners heard a set of 8 The current study melodies that were very distinct from each other in terms of The current study examined influences of mode, rate, and timbre, note rate (speed), mode (major, minor, other), and timbre on the metrical restoration effect. Experiment 1 rhythmic patterns. Listeners provided higher ratings for asked whether differences in mode (major or minor), alone drumbeat probes that matched the contexts they had heard or in combination with timbre cues, show specificity effects with those specific melodies during the exposure phase. in metrical restoration. Experiment 2 asked whether This suggests melody-specific memory for meter. maximal differences in timbre (1 vs. 12 timbres), and A second study (Creel, 2012) examined the role of cross- differences in rate, allow even more specificity in memory. melody similarity on metrical restoration, and so presented melodies with a stronger similarity structure: two timbres, a Experiment 1 single note rate, and similar rhythmic patterns across The first experiment compares metrical restoration as a melodies. Listeners associated metrical information with function of timbre-specificity (shown in Creel, 2012) and timbre: they showed metrical restoration for a melody mode-specificity (not yet explored). We know that listeners played in its original timbre, but not when it was played in show timbre-specific metrical restoration when timbre the other timbre (as long as timbre and meter patterned patterns consistently