Investigating Emotional Contagion in Dogs (Canis Familiaris) to Emotional Sounds of Humans and Conspecifics
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Anim Cogn DOI 10.1007/s10071-017-1092-8 ORIGINAL PAPER Investigating emotional contagion in dogs (Canis familiaris) to emotional sounds of humans and conspecifics 1 1 2 1 Annika Huber • Anjuli L. A. Barber • Tama´s Farago´ • Corsin A. Mu¨ller • Ludwig Huber1 Received: 1 October 2016 / Revised: 10 April 2017 / Accepted: 12 April 2017 Ó The Author(s) 2017. This article is an open access publication Abstract Emotional contagion, a basic component of emotional state-matching or emotional contagion for neg- empathy defined as emotional state-matching between ative sounds of humans and conspecifics. It furthermore individuals, has previously been shown in dogs even upon indicates that dogs recognized the different valences of the solely hearing negative emotional sounds of humans or emotional sounds, which is a promising finding for future conspecifics. The current investigation further sheds light studies on empathy for positive emotional states in dogs. on this phenomenon by directly contrasting emotional sounds of both species (humans and dogs) as well as Keywords Empathy Á Emotional contagion Á Playback opposed valences (positive and negative) to gain insights study Á Dogs into intra- and interspecies empathy as well as differences between positively and negatively valenced sounds. Dif- ferent types of sounds were played back to measure the Introduction influence of three dimensions on the dogs’ behavioural response. We found that dogs behaved differently after Empathy is a social phenomenon that can be defined as hearing non-emotional sounds of their environment com- ‘‘the capacity to […] be affected by and share the emo- pared to emotional sounds of humans and conspecifics tional state of another’’ (de Waal 2008, p. 281). Preston and (‘‘Emotionality’’ dimension), but the subjects responded de Waal (2002) proposed a multi-level concept of empathy, similarly to human and conspecific sounds (‘‘Species’’ whose most basic level is emotional contagion, defined as dimension). However, dogs expressed more freezing an automatic and unconscious emotional state-matching behaviour after conspecific sounds, independent of the between two individuals (Preston and de Waal 2002;de valence. Comparing positively with negatively valenced Waal 2008). Hatfield et al. (1993) considered the functional sounds of both species (‘‘Valence’’ dimension), we found significance of emotional contagion as: ‘‘[…] [It] may well that, independent of the species from which the sound be important in personal relationships because it fosters originated, dogs expressed more behavioural indicators for behavioural synchrony and the moment-to-moment track- arousal and negatively valenced states after hearing nega- ing of other people’s feelings even when individuals are tive emotional sounds. This response pattern indicates not explicitly attending to this information’’ (Hatfield et al. 1993, p. 96). Consequently, emotional contagion can have important facilitation effects in the social domain, which is & Annika Huber not only restricted to our own species’ social life—emo- [email protected] tional contagion is a phylogenetically old capacity (Palagi 1 et al. 2014), which suggests the existence of this emotional Clever Dog Lab, Comparative Cognition, Messerli Research level of empathy also in non-human animals. Institute, University of Veterinary Medicine Vienna, Medical University of Vienna, University of Vienna, 1210 Vienna, Emotional contagion has been demonstrated in various Austria animal species ranging from primates (e.g. Parr 2001; Ross 2 MTA-ELTE Comparative Ethology Research Group, et al. 2008; Palagi et al. 2009, 2014) to rodents (e.g. Pa´zma´ny Pe´ter se´ta´ny 1/C, 1117 Budapest, Hungary Langford et al. 2006; Bartal et al. 2011, 2014) and avian 123 Anim Cogn species (e.g. Edgar et al. 2011; Osvath and Sima 2014), and evidence for emotional contagion in dogs triggered solely it has been suggested in farm animals (Reimert et al. by the detection of the heterospecifics’ acoustic cues (Yong 2013, 2015). Furthermore, evidence for emotional conta- and Ruffman 2014). Finally, another playback study found gion has been found in pet animals, more precisely in dogs evidence for an empathetic response to distress vocaliza- (e.g. Zahn-Waxler et al. 1984; Joly-Mascheroni et al. 2008; tions in dogs on an intraspecies level (Quervel-Chaumette Custance and Mayer 2012; Silva et al. 2012; Madsen and et al. 2016). Thus, both an interspecies empathetic response Persson 2013; Yong and Ruffman 2014; Palagi et al. 2015; and an intraspecies empathetic response to negatively but see Harr et al. 2009; O’Hara and Reeve 2011). Dogs are valenced emotional states, triggered solely by acoustic exceptional as several studies have indicated that they stimuli, could be demonstrated in dogs. express empathy even towards other species, in this case Our aim was to further shed light on emotional conta- humans (e.g. Zahn-Waxler et al. 1984; Custance and Mayer gion in dogs to acoustic stimuli of different meanings. 2012;Su¨megi et al. 2014; Yong and Ruffman 2014). This Therefore, we applied a playback study where we analysed cross-species occurrence of empathy makes further for the first time three dimensions simultaneously: first, we research with dogs highly valuable as a resource for analysed the ‘‘Emotionality’’ dimension by contrasting increasing our understanding of this social phenomenon non-emotional sounds of the dogs’ environment with (see for an opinion Silva and de Sousa 2011). emotional sounds of humans and conspecifics. Second, we Empirical evidence about dogs’ sensitivity to emotional analysed the ‘‘Species’’ dimension by contrasting emo- states in humans is accumulating. Recently, a study has tional sounds of humans with those of conspecifics. Third, demonstrated dogs are capable of discriminating between we analysed the ‘‘Valence’’ dimension by contrasting different emotional expressions in human faces (Mu¨ller positively with negatively valenced sounds of both species. et al. 2015); similar results on heterospecific emotion dis- Comparing these different dimensions within one experi- crimination have also been found in horses (Smith et al. mental paradigm provides the possibility to simultaneously 2016a; but see Schmoll 2016; Smith et al. 2016b). Fur- gain new insights into intra- and interspecies empathy in thermore, on a multimodal level combining visual with dogs as well as into differences in responses relating to acoustic stimuli, dogs can extract, integrate, and discrimi- positive and negative emotional states. This is important nate humans’ as well as conspecifics’ emotional expres- both from a fundamental science perspective to increase sions (Albuquerque et al. 2016). Focussing particularly on our knowledge on animal emotions and behaviour as well empathy, a recent questionnaire study investigated dog as for considering possible additional effects of domesti- owners’ evaluation of empathic-like responding in their cation and socialization in terms of canine emotional dogs (Sza´ntho´ et al. 2017). However, apart from this first contagion. Along with the functional significance of emo- survey-based approach of the topic, previous studies tional contagion (see Hatfield et al. 1993), one could expect focussed on behavioural observations of dogs confronted that the human–dog relationship can also be facilitated by with emotional situations in an intraspecies context and an heterospecific emotional contagion. Thus, research on this interspecies context. Thus, dogs have been shown to phenomenon could provide new insights concerning express comfort-offering behaviours to a human suddenly influential but so far less considered effects on this inter- pretending to cry—a response that has been interpreted as species relationship. Apart from that, knowledge on canine demonstrating empathic-like behaviour driven by emo- emotional contagion is important from an applied per- tional contagion (Custance and Mayer 2012). This does spective in terms of relevant effects on animal welfare, i.e. not, however, imply that dogs understand the nature of the when dogs emotionally resonate with vocalizations they cry as an expression of emergency or the need to obtain hear from humans and other dogs, and this will affect their help for the crying person. In a study by Macpherson and own emotional state and, consequently, their welfare. Roberts (2006), dogs failed to solicit help from a bystander We evaluated the dogs’ behavioural responses towards when the dog’s owner feigned a heart attack or experienced their owner and towards a loudspeaker broadcasting the an accident. Still, this is not evidence that dogs are apathic stimulus. Furthermore, we analysed behaviours that have towards people in need and thus not evidence against been identified in previous studies as being indicative for empathic-like behaviour driven by emotional contagion. arousal and negative emotional states in dogs. For the Given dogs’ sensitivity to vocal emotional valence ‘‘Emotionality’’ dimension, we hypothesized dogs perceive features of human and conspecific sounds (Andics et al. the emotional features of sounds, based on findings that 2014), it is likely that an empathetic response is induced in they are sensitive to emotional sounds of humans and dogs by solely hearing an emotional vocalization. conspecifics (Andics et al. 2014) and behave in expected Accordingly, on an interspecies level, a playback study that manner to them (Custance and Mayer 2012; Yong and investigated dogs’ responses to vocalizations of human Ruffman 2014;