Perception of emotional prosody: investigating the relation between the discrete and dimensional approaches to emotions

Abstract: Emotional phenomena can be described according to various psychological approaches, the most adopted being the discrete (basic) and the dimensional ones. This study aimed at investigating the relation between the perception of some basic emotions and emotional dimensions in speech, as well as determining which acoustic cues are related to their perception. We conducted two perception experiments with utterances selected from a foreign language (Swedish) of which the listeners had no knowledge. In the first one, Brazilian subjects rated on 5-point scales the expressivity of four basic emotions: joy, anger, sadness, and calmness. In the second, a distinct group of Brazilian subjects rated the expressivity of five emotional dimensions: activation, fairness, valence, motivation, and involvement. The perception of the basic emotions and of the emotional dimensions was then compared by means of the Spearman’s correlation coefficient. The five emotional dimensions were significantly correlated to some extent with the basic emotions, and these correlations were, in general, consistent with the literature and with the hypotheses that guided this study. We also performed an acoustic analysis, in which twelve acoustic parameters were automatically computed for the utterances evaluated by the listeners. The parameters which correlated better with the listeners’ judgments were fundamental frequency (median, interquantile semi-amplitude, 99.5% quantile), spectral tilt (mean and standard deviation), and LTAS slope. We concluded that it is possible to describe the perception of basic emotions in speech as a combination of emotional dimensions and that emotional dimensions may be better for describing the expression of emotions in speech. Keywords: emotional prosody; basic emotions; emotional dimensions; perception test. Resumo: Os fenomenos emocionais podem ser descritos de acordo com varias abordagens psicologicas, sendo a discreta (basica) e a dimensional as mais adotadas. Este estudo teve como objetivo investigar a relacao entre a percepcao de algumas emocoes basicas e dimensoes emocionais na fala, bem como determinar quais pistas acusticas estao relacionadas com sua percepcao. Conduziram-se dois experimentos de percepcao com enunciados selecionados de uma lingua estrangeira (sueco) da qual os ouvintes nao possuiam nenhum conhecimento. No primeiro, sujeitos brasileiros julgaram em escalas de cinco pontos a expressividade de quatro emocoes basicas: alegria, raiva, tristeza e calma. No segundo, um grupo distinto de sujeitos brasileiros avaliou a expressividade de cinco dimensoes emocionais: ativacao, justica, valencia, motivacao e envolvimento. A percepcao das emocoes basicas e das dimensoes emocionais foi entao comparada por meio do coeficiente de correlacao de Spearman. As cinco dimensoes emocionais correlacionaram-se significativamente em algum grau com as emocoes basicas e essas correlacoes foram, no geral, consistentes com a literatura e com as hipoteses que nortearam este estudo. Realizou-se tambem uma analise acustica, na qual doze parâmetros acusticos foram computados automaticamente para os enunciados avaliados pelos ouvintes. Os parâmetros que melhor se correlacionaram com os julgamentos dos ouvintes foram: frequencia fundamental (mediana, semiamplitude entre quantis, quantil 99,5%), inclinacao espectral (media e desvio padrao) e inclinacao do LTAS. Concluiu-se que e possivel descrever a percepcao das emocoes basicas na fala como uma combinacao de dimensoes emocionais e que as dimensoes emocionais podem ser melhores para descrever a expressao de emocoes na fala. Palavras-chave: prosodia emocional; emocoes basicas; dimensoes emocionais; teste de percepcao.