Emotions are contagious!

Emotions are contagious! They are transmittable from individuals of the same as well as different species. To what extent they are transmittable and between which living beings, this is content of current and future science. The transmission of an emotion to another individual has already been proven in a large number of species. This occurs not only in mammals, but also in birds. 


Emotional contagion is the emotional response triggered by the perception of the emotional state of another individual. In particular, this occurs among members of social groups or families with whom there is a strong social relationship or bond. Emotional contagion is thought to facilitate communication and coordination in complex social groups. The matching of emotional state between individuals is a mechanism for information sharing. This can facilitate defense against predators or social group living. Emotional contagion is proposed as a core element of empathy. According to scientists, the occurrence of empathic behavior has not only a genetic component, but perhaps much more of a learned component. According to them, empathic behavior arises from learning processes and can be strengthened or weakened depending on experiences. Empathy is an important element of morality. Emotional contagion and the learning experiences made from it therefore have an important position with regard to empathy and morality.


Most scientific studies on emotional contagion between humans and animals involve our domesticated pets. For example, scientific studies dealt with emotional contagion between dogs and humans. The dog, they sai, is a unique animal and the oldest domesticated species. Dogs have coexisted with humans for more than 30,000 years and are woven into human society as bonding partners. Dogs have acquired human-like communication skills and, probably as a result of the domestication process, the ability to read human emotions. Therefore, some researchers are convinced that there is emotional contagion between humans and dogs. However, scientific evidence of what is often taken for granted in the everyday life of dog owners, due to the complexity of such experiments that is actually required, still needs to be developed. 


As an example, one study examined the emotional responses of dogs and humans using heart rate variability, which is thought to reflect emotions. A psychological stress condition was created in owners and the dogs' heart rates were measured simultaneously. Correlation coefficients of heart rate intervals between dogs and owners were positively correlated with duration of dog ownership. The sex of the dogs influenced this as well. Female animals showed stronger values. These results suggest that emotional contagion from owner to dog may occur primarily in female dogs and that the time they share the same environment is the key factor in the effectiveness of emotional contagion.


Empirical studies measuring emotional contagion usually focus on measuring behavioral contagion as well as the extent of emotional arousal. It must actually be taken into account that imitation of a particular behavior does not necessarily imply the contagion of a corresponding emotion. Behavioral and physiological measurements do form meaningful indicators of an animal's emotional state and thus of possible contagion. However, these components primarily assess emotional arousal. However, an emotion is defined by both its arousal level and its positive or negative valence. Thus, unlike the measurement of arousal, the quantification of emotional valence often remains unexplored. 


Changes in emotional states correlate with changes in behavioral, physiological, and cognitive components. Human emotions often include an additional subjective "feeling" component that is currently considered difficult to measure directly in nonhuman animals. Accordingly, the majority of animal research has focused on objectively measurable components to determine the presence and nature of an emotional state. For example, locomotor activity may be an animal approaching or avoiding a stimulus. This behavior can inform the rewarding or non-rewarding qualities of a stimulus triggering the emotion. Measurement of physiological parameters such as heart rate or cortisol levels are methods of measuring arousal levels. 


However, animals tend to react individually to stimuli due to differences in personalities. Thus, it is more complex to study the emotions of animals! Components like alertness, the motivation to explore new contexts and the activity level in general have to be considered, among other parameters! Thus, if we measure only one behavioral component instead of a larger set, we limit and potentially confound our interpretations of the emotional state in question!





- Adriaense et al. (2019) Negative emotional contagion and cognitive bias in common ravens (Corvus corax), Proc Natl Acad Sci U S A 116(23):11547-11552.

- Albuquerque N, Guo K, Wilkinson A et al. Dogs recognize dog and human emotions. Biol Letters 2016; 12: 20150883. http://dx.doi.org/10.1098/rsbl.2015.0883

- Heyes(2018) Empathy is not in our genes, Neuroscience & Biobehavioral Reviews 95:499-507.

- Katayama et. al. (2019) Emotional Contagion From Humans to Dogs Is Facilitated by Duration of Ownership, Front Psychol 10:1678.