Enculturation to Western Musical Pitch Structure in Young Children

knowledge of key membership and harmony to develop in the first place, given its emphasis on pitch patterns. If Western adults have become fully enculturated to the pitch structure of the music of their culture but infants have not yet acquired this sensitivity, then it is reasonable to ask when this skill develops in childhood. Unfortunately, few studies have been conducted with children to examine their knowledge of key membership and harmony, especially in children below the age of 6 years. Corrigall, K.A. – Ph.D. Thesis McMaster – Psychology, Neuroscience & Behaviour 19 Despite the scarcity of research on this important aspect of development, one key finding to emerge from previous research is that children first acquire knowledge of key membership, and then later develop the more sophisticated ability to perceive harmonic relationships. In one change detection study, 4and 5-year-old children were better at detecting a changed note in a melody that conformed to the major scale than in a melody that did not, suggesting biased processing for Western key structure (Trehub, Cohen, Thorpe, & Morrongiello, 1986). In another change detection study, 7-year-olds and adults could easily detect changes to a Western major melody that went outside the key or that remained in key but did not fit the appropriate implied harmony at that point, but they had more difficulty detecting changes that fit both the key of the melody and the implied harmony (Trainor & Trehub, 1994). By contrast, 5-year-olds showed evidence of only detecting changes that violated key structure, suggesting that they had knowledge of key membership but not harmony. In an implicit reaction time study using chordal rather than melodic stimuli, Schellenberg and colleagues showed that 6to 7-year-olds are sensitive to harmony (Schellenberg et al., 2005). Together, these studies suggest that children understand implicitly which notes and chords belong in a key and which do not before they understand the more nuanced hierarchical structure of notes and chords within a given key. Still, some unanswered questions remain, such as whether the developmental timeline for knowledge of key membership and harmony differs for melodic compared to chordal stimuli, whether younger children can demonstrate partial knowledge of Corrigall, K.A. – Ph.D. Thesis McMaster – Psychology, Neuroscience & Behaviour 20 the pitch structure of Western music, and whether biased processing for aspects that conform to Western music structure implies that children consciously perceive violations to the expected structure as sounding surprising or even wrong, as enculturated adults do. To examine children’s explicit, evaluative judgments of the appropriateness of the notes of the chromatic scale, several studies have used a probe tone method that has been simplified for use with children, for example, by reducing the rating scale from a 7-point Likert scale to a 3-point scale comprised of a sad, neutral, and happy face. These studies have shown that by approximately 6 years of age, children exhibit adult-like sensitivity to the tonal hierarchy, giving the highest ratings to the notes of the tonic triad, followed by other in-key notes, and by giving the lowest ratings to out-of-key notes (e.g., Cuddy & Badertscher, 1987; Speer & Meeks, 1985). However, there appears to be some further development of this sensitivity from 6 to 10 years (Krumhansl & Keil, 1982). Yet no studies to date have tested whether children below the age of 6 years can make explicit judgments that reflect knowledge of key membership and harmony. Furthermore, it is unknown whether young children can make explicit judgments about the appropriateness of chordal stimuli. Methodological Issues Associated with Testing Young Children’s Music Perception One reason for the scarcity of research on children’s music perception between infancy and school age is that there has been a lack of age-appropriate Corrigall, K.A. – Ph.D. Thesis McMaster – Psychology, Neuroscience & Behaviour 21 methods that are suitable for use with toddlers and preschool-aged children. The conditioned head turn and head turn preference methods that are typically used with infants are no longer appropriate for older children who can provide verbal as well as nonverbal (e.g., pointing) responses, and other methods that are typically used with adults – such as the probe tone method, change detection, and reaction time tasks – require many trials and therefore long bouts of sustained attention, which can be very difficult for young children. Adult methods also tend to require behaviours that are too sophisticated for young children to perform, such as using ratings scales and making speeded judgments. Furthermore, existing methods have all presented auditory stimuli with no accompanying visual display, which make it difficult to engage children’s full attention, especially for children in today’s society who live in a multimedia-rich environment. Thus, there is a need for more age-appropriate behavioural methods that can be used to examine the development of young children’s knowledge of Western musical pitch structure. Although it important to develop appropriate behavioural methods to understand what children consciously perceive when listening to music that does or does not conform to Western pitch structure, neurophysiological methods such as electroencephalography (EEG) can be used to assess implicit musical knowledge in young children. In adults, an event-related potential (ERP) component referred to as the early right anterior negativity (ERAN) is typically elicited to chords that violate Western key or harmony structure (e.g., Koelsch, Corrigall, K.A. – Ph.D. Thesis McMaster – Psychology, Neuroscience & Behaviour 22 Gunter, Friederici, & Schröger, 2000; Koelsch et al., 2001; see Koelsch, 2009 for a review). The ERAN has also been found in children as young as 5 years of age in response to strong violations to key membership (Koelsch et al., 2003) and to harmony (Jentschke, Koelsch, Sallat, & Friederici, 2008); however, there are no published data on children younger than 5 years. Although neurophysiological methods require many trials, the ERAN is reliably elicited under passive listening conditions where children can focus their attention on a silent movie while musical stimuli play in the background. Thus, EEG can be an ideal method to study young children’s implicit musical knowledge. Outline and Significant Contributions of Thesis Experiments Chapters 2, 3, and 4 are aimed at addressing many of the methodological issues that have limited the study of music perception in young children, and to further refine our understanding of the development of enculturation to musical pitch structure. Experiment 1 in chapter 2 presents a novel method for testing 4and 5-year-olds’ explicit knowledge of key membership and harmony in unfamiliar chord sequences and melodies, in which children watched videos of puppets playing songs that did or did not conform to Western pitch structure and awarded prize ribbons to the puppets that played the best songs. As this procedure was very engaging for children and required many fewer trials than existing methods, I was able to study younger children than has been possible with the probe-tone method. Furthermore, the development of sensitivity to key membership and harmony could be directly compared in the context of both Corrigall, K.A. – Ph.D. Thesis McMaster – Psychology, Neuroscience & Behaviour 23 natural chord progressions and simple melodies, using more ecologically valid stimuli than previous experiments that used scales or triads as stimuli. Finally, the generalizability of the results was improved compared to previous studies because a different musical sequence was presented on each trial, ensuring that children’s responses reflected their abstract knowledge of Western pitch structure rather than the accumulation of knowledge about the particular sequence presented within the experiment. Chapters 3 and 4 present a second novel method for testing young children’s explicit knowledge of key membership and harmony in a familiar song in three contexts: the melody alone, the melody accompanied by chords, and the chords alone. On each trial, children decided if a puppet’s song was played correctly or incorrectly or if it sounded good or bad using happy-face and sad-face hand signs. Using this method, I was able to demonstrate behavioural sensitivity to both key membership and harmony in the youngest children to date (i.e., 4year-olds) in the context of a familiar song, suggesting that young children may have partial knowledge of Western pitch structure before they become fully enculturated listeners. Furthermore, through the use of a longitudinal design, chapter 4 shows that experience drives enculturation. Specifically, there were no pre-existing differences in sensitivity to key membership and harmony at the first measurement in children who had just begun music lessons compared to children who were not enrolled in lessons, but after approximately one year of lessons, musically trained children outperformed their nonmusically trained peers. Corrigall, K.A. – Ph.D. Thesis McMaster – Psychology, Neuroscience & Behaviour 24 Experiment 2 in chapter 2 was aimed at testing implicit or pre-conscious knowledge of Western pitch structure in 4-year-old children who did not demonstrate behavioural sensitivity to either key membership or harmony in unfamiliar but typical Western sequences (Experiment 1 of chapter 2). Using EEG, we recorded children’s ERPs to chord sequences and melodies that ended either according to Western harmony rules, or that ended on a chord or note that violated key membership or harmony. We found an immature but ERAN-like response to violations of key and harmony in chord sequences. These results converged with the behavioural findings of Chapters 3 and 4 suggesting that children as young as 4 years of age