Music is a human universal, although it serves no apparent adaptive function. This is cause for curiosity and speculation about its motivational and functional basis. Folk psychology asserts that music “has something to do with” emotions, presumably based on the incidence of musical behaviors paired with pleasurable experiences. This implies little about causality, however: Just for the sake of argument, it could mean that music induces pleasurable experiences, that a happy state of mind prompts me to sing and dance (or to put on a CD), or that this association is the effect of other, underlying factors.
Juslin & Västfjäll (J&V) argue that it is important to explain listeners' reactions to music. I emphatically agree, but note that several different levels of explanation may obtain. For example, one might want to understand why music induces reactions. One might also be interested in the specific effects of various musical features: If some mapping from musical or sound features to reactions could be made, it might help design and improve therapies. But then one would also need to know to what extent and in which ways contextual variables affect reactions induced by the same stimulus. Perhaps experiencing music in a group setting induces stronger or different reactions than being alone (Merker et al., in press). All these questions represent levels of explanation that are not directly addressed by the systematization of psychological mechanisms and their characteristics provided by the target article, which purports to “explain[s] how such emotions are induced” (sect. 1, para. 11) – rather than why. To be sure, none of the 66 hypotheses listed in J&V's Table 4 include music-specific variables. Emotional reactions due to brain stem reflexes, episodic memory, and evaluative conditioning could all be induced by a wide range of stimuli. Emotional contagion is a possibility for any stimulus perceived as emotionally expressive, and whether visual imagery is more effective in response to music than to other stimuli remains an open question (Aleman et al. Reference Aleman, Nieuwenstein, Böcker and de Haan2000). Inasmuch as it yields predictions and helps to organize knowledge (in the sense of a theory), this systematization is therefore relevant to the measurement and understanding of emotion in general, not specifically to emotions induced by music (cf. Scherer Reference Scherer2004).
The only mechanism proposed that is clearly music-specific is musical expectancy. I think that discussing additional mechanisms would be very fruitful, and might lead to a number of testable hypotheses (cf. Peretz Reference Peretz2006). A commentary does not provide space for developing such hypotheses, so I will instead summarize a few key aspects that emerge from adopting a functional perspective on the relation between music and affective responses (Madison, in press).
The function of emotions and affective responses in general is to guide action, with negative feelings directing us away from that which may ultimately threaten well-being and positive feelings directing us to that which ultimately facilitates well-being (Frijda Reference Frijda1986). Everyday observations as well as research show that affective responses in connection with music are overwhelmingly positive (Juslin & Laukka Reference Juslin and Laukka2004; Scherer et al. Reference Scherer, Zentner and Schacht2001–2002), even when the music is characterized as sad (Schellenberg et al. Reference Schellenberg, Peretz and Vieillard2008), or when musicians try to express different emotions (Juslin & Madison Reference Juslin and Madison1999). In contrast, the valence of affective responses that act on associations acquired through personal life experience, such as those provided by evaluative conditioning, episodic memory, and visual imagery, is on average likely to be neutral. An innate ground for affective responses to music seems, therefore, to be in play, presumably as a motivational machinery for engaging in musical behaviors.
The function of music, in contrast, is a matter of debate (e.g., Fitch Reference Fitch2006; Kivy Reference Kivy2002; Miller Reference Miller, Wallin, Merker and Brown2000; Pinker Reference Pinker1997), but this does not preclude the formulation of quite specific ideas. Common themes include: (1) that the induction and communication of emotion constitutes a function of music and a reason why we are attracted to it (Cooke Reference Cooke1959; Juslin Reference Juslin, Juslin and Sloboda2001; Meyer Reference Meyer1956); (2) that music evolved as a sexually selected courtship display (Darwin Reference Darwin1871/1902; Miller Reference Miller, Wallin, Merker and Brown2000); (3) that music may have a bonding effect that facilitates cooperative activity and social organization (Freeman Reference Freeman, Wallin, Merker and Brown2000; Roederer Reference Roederer1984; Ujhelyi Reference Ujhelyi, Wallin, Merker and Brown2000); and (4) that language and music likely have been cooperative, in the sense that music might have supported the evolution of language, or vice versa, or both, during some period of their common evolutionary history (Brown Reference Brown, Wallin, Merker and Brown2000; Mithen Reference Mithen2005; Molino Reference Molino, Wallin, Merker and Brown2000; Richman Reference Richman, Wallin, Merker and Brown2000). These themes include both proximal and ultimate functions; some of them indicate a direct selection pressure for the evolution of musical faculties, and others do not. For the purpose of the present commentary, however, the point is that they implicate testable hypotheses regarding the interaction between musical behaviors, the conditions in which they occur, and their motivational mechanisms.
For example, it has been suggested that our capacity to entrain to a common pulse occurred during the period of speciation between chimpanzees and early hominids (Merker Reference Merker, Wallin, Merker and Brown2000). This is a key feature of dance, as well as of performing and listening to music, and is associated with pleasurable feelings (Madison Reference Madison2006). We can therefore posit that an additional entrainment mechanism contributes to reactions to music. Links between sensory and reward systems suggest that actually entraining to an external signal might be more pleasurable than passively listening to it (e.g., Todd & Cody Reference Todd and Cody2000), which is but one example of such an hypothesis.
The main contribution of the target article is to emphasize that one should discriminate between mechanisms on the basis of their characteristics so as to reduce discrepancies in results and interpretations. It is my impression that students of emotion already do so, and that the “cognitive appraisalist” that J&V challenge may be more of a straw man than a dominant character. This may not be the case in the field of music, however, and, if so, the article serves a useful purpose for reducing possible measurement and interpretation problems in future research. But to explain affective responses to music requires us to come to grips with the different properties or functions of music, in addition to analyzing the mechanisms that convey the affective responses it may induce.
