Modeling Melodic Perception as Relational Learning Using a Symbolic-Connectionist Architecture (DORA)

Modeling Melodic Perception as Relational Learning Using a Symbolic- Connectionist Architecture (DORA) Ahnate Lim (ahnate@hawaii.edu) Department of Psychology, University of Hawaii at Manoa 2530 Dole Street, Honolulu, HI 96822 USA Leonidas A. A. Doumas (leonidas@hawaii.edu) Department of Psychology, University of Hawaii at Manoa 2530 Dole Street, Honolulu, HI 96822 USA Scott Sinnett (ssinnett@hawaii.edu) Department of Psychology, University of Hawaii at Manoa 2530 Dole Street, Honolulu, HI 96822 USA Abstract characterize and store familiar melodies (Attneave & Olson, 1971). Another characteristic upon which melodies can be categorized, however, is according to the contour (general shape, or sequence of up and down movements in frequencies from note to note). Given the existence of these various characteristics, there has been considerable research and speculation on the extent to which these categorizations contribute to a listener’s mental representation of a melody, and how they may interact. Like many other cognitive processes, the perception of music involves processes and structural considerations that are highly relational in nature. To date, no physiologically plausible model has been used to simulate and explain how infants perceive melodic content. Here we used DORA (Discovery Of Relations by Analogy; Doumas et al., 2008), a domain-general symbolic-connectionist model of relational learning, to simulate melodic perception and categorization by infants (Chang & Trehub, 1977; Trehub et al, 1984), and to provide an account of the mechanism for melodic processing in infants. Given four input semantic features for each note in the melodic stimuli sequence (two of which could be internally obtained from the other two via a comparator), DORA’s performance matched the behavioral data from the infant studies. Furthermore, the ability of our model to simulate infants’ behavior is evidence that structured representations of relational musical properties can be bootstrapped from unstructured feature representations. Relative pitch and melodic contour The properties of relative pitch (or intervallic patterns) are most commonly used in long term musical storage and recall (Page, 1994). For example, when listening to the melody of a song, such as Happy Birthday, what makes the song immediately recognizable is the unique intervals between each of the notes in the song. That is, the song is recognizable whether it initially starts on a low or high note due to the unique intervallic pattern between all subsequent notes. There is much evidence on the use of relative pitch information in adults through both behavioral studies (Dowling, 1978, 1984, 1988) as well as neuroimaging studies (Fujioka, Trainor, Ross, Kakigi, & Pantev, 2004; Trainor, McDonald, & Alain, 2002). It is worth noting that while a melody with an identical contour to Happy Birthday, but with a different intervallic sequence would sound like a completely different tune, it would still have the same general “shape”, or up and down pattern. Although the intervallic pattern may be the most overtly salient feature of a melody, studies have shown that human adults are also sensitive to absolute pitch and melodic contour in the short term (Bartlett & Dowling, 1980; Dowling, 1978). And while there is evidence that infants may also be sensitive to intervallic information (Trehub, Bull, & Thorpe, 1984), numerous experiments with infants suggest that they may primarily encode melodies using contour information (for review, see Trehub, 2001; Trehub, Trainor, & Unyk, 1993). Even though intervallic and contour properties may characteristically differ in the type of information they Keywords: Melodic perception; relative pitch; relational learning; symbolic connectionist; DORA. Introduction While there are many defining characteristics of music (e.g., harmony, rhythm, timbre, pitch, etc.), one of the most fundamental and salient aspects is the melody. Indeed, simple melodies were likely the earliest form of music to have been created and transmitted, and have been (and still are) prevalent in all documented cultures past and present (Sachs, 1943). Simple melodies consist of discrete units or notes, with each note characterized by a pitch, or fundamental frequency. Importantly, there are several ways in which the pitch sequence of a melody can then be encoded and stored. The two most well documented forms of encoding are absolute or relative pitch. Absolute pitch encodes and stores a melody using the fundamental frequencies of each pitch, while relative pitch (or intervallic) encodes the melody in terms of the relations (or specific frequency differences) between each note. Notably, processing melodies in terms of the relative pitch information (or intervallic patterns) is considered to be the strategy most humans use to