Abstract:

Music and language are unique to the human beings. It has been suggested that music and language have a common origin as an emotional protolanguage. The development of socialisation has resulted in the development of language into a symbolic communication system with explicit semantics. By contrast, music has become an important means of emotional expression. However, whether language with explicit semantics affects the emotional processing of music remains uncertain. Given that songs contain melody and lyrics, previous behavioural studies have focused on songs to analyse the influence of lyrics on the processing of musical emotion. However, several studies have also shown the influence of lyrics, although such findings are relatively contradictory.

Thus, the current study used behavioural and electrophysiological measurements to investigate the impact of lyrics on the processing of musical emotion. Experiment 1 analysed whether the emotional connotations in music with and without lyrics could be perceived by listeners at the behavioural level. Experiment 2 further investigated whether there are different neural responses to emotions conveyed by melodies with and without lyrics.

A cross-modal affective priming paradigm was used in Experiments 1 and 2, in which musical excerpts served as the prime and emotional faces as target. To avoid the impact of familiarity, 120 musical stimuli were selected from European opera. Each was sung by a vocalist with and without lyrics, thereby resulting in 240 musical stimuli in two versions as potential prime stimuli. A total of 160 facial expressions affectively congruent or incongruent with the preceding musical stimuli were selected as potential target stimuli. Three pre-tests were conducted to ensure the validity of the stimuli. Eventually, 60 musical stimuli for each music version were selected as the prime stimuli, whilst 120 images were used as the target stimuli, thereby resulting in 240 music-image pairs. To ensure that each stimulus appears only once for each participant, two lists were prepared using a Latin square design. Each prime and target was presented in either the congruent or incongruent condition within each list. Thus, each list comprised 120 trials, with 30 trials in each condition. During the experiment, the two lists were equally distributed across the participants. A total of 40 healthy adults participated in Experiment 1. They were asked to judge as quickly and accurately as possible whether the emotion of the target was happy or sad. The accuracy and reaction time were collected. Meanwhile, 20 healthy adults participated in Experiment 2. They were required to judge whether the emotion between music and image was congruent or incongruent whilst their EEG waveforms were recorded. ERPs were analysed and compared between conditions at the time windows of 250~450 ms and 500~700 ms after the onset of the target.

The Experiment 1 results showed that when faces were primed by music either with or without lyrics, the participants responded faster and more accurately under affectively congruent condition compared with affectively incongruent condition. This finding indicated that the emotional connotations in music with and without lyrics could both be perceived. The ERP results in Experiment 2 showed that distinct neural mechanisms were activated by music with and without lyrics. Specifically, when faces were primed by music without lyrics, a larger N400 was elicited in response to affectively incongruent pairs than to affectively congruent pairs at the time window of 250~450 ms. However, when faces were primed by music with lyrics, a more positive LPC was observed in response to the affectively incongruent pairs than to the affectively congruent pairs at 500~700 ms. This finding confirms the results of Experiment 1, thereby suggesting that the emotion conveyed by music with and without lyrics could be perceived by the listeners. Moreover, the emotional processing between music with and without lyrics differs in the time course of neural processing. That is, the emotional processing of music with lyrics lagged behind that of music without lyrics.

In conclusion, the present results suggest that the neural processing of emotional connotations in music without lyrics preceded that of music with lyrics, although the emotional connotations conveyed by music with and without lyrics could both be perceived. These findings also supported theory of musical philosophy, which suggests that music without lyrics can express emotion more immediately and more directly than music with lyrics owing to the lack of “translation” from the propositional system. On the other hand, considering that lyrics influenced the time course of emotional processing in music with lyrics, our results also provide evidence that the emotional processing of music and language may share neural resources to some extent.

Key words: musical emotion, language, lyrics, N400, LPC