. 2021 May 5;13(1):e1560. doi: 10.1002/wcs.1560

TABLE 1.

Summary of measures and stimuli used in the reviewed studies on emotional contagion

	Measures
Stressed conspecific	Rhesus macaques (Miller et al., 1963)	Pigs (Goumon & Špinka, 2016)	Chimpanzees (Parr & Hopkins, 2000) video	Prairie voles (Burkett et al., 2016)
Prairie and meadow voles (Burkett et al., 2016)
Rats (Knapska et al., 2010; Mikosz et al., ²⁰¹⁵; Rogers‐Carter et al., ²⁰¹⁸)	Pigs (Reimert et al., 2013, 2015)
Mice (Ueno et al., 2020)
Asian elephants (Plotnik & de Waal, 2014; Sharma et al., ²⁰²⁰)	Zebrafish (Oliveira et al., 2017)
African elephants (Douglas‐Hamilton et al., 2006; Schulte, ²⁰⁰⁰)
Pigs (Goumon & Špinka, 2016)
Zebrafish (Fernandes da Silva et al., 2019; Oliveira et al., ²⁰¹⁷)
Stressed conspecific (only auditory cues)	Mice (Chen et al., 2009)	Chimpanzees (Berntson et al., 1989)	Horses (Briefer et al., 2017)	Dogs (Quervel‐Chaumette et al., 2016)		Rats (Saito et al., 2016)
Dogs (Huber et al., 2017; Quervel‐Chaumette et al., ²⁰¹⁶)
Goats (Baciadonna et al. 2019)	Mice (Chen et al., 2009)
Horses (Briefer et al., 2017)
Cockatiels (Liévin‐Bazin et al., 2018)	Goats (Baciadonna et al. 2019)	Zebra finches (Perez et al., 2015)
Zebra finches (Perez et al., 2015)	Horses (Briefer et al., 2017)
Stressed human	Dogs (Carballo et al., 2020; Custance & Mayer, ²⁰¹²; D'Aniello et al., ²⁰¹⁸; Huber et al., ²⁰¹⁷; Sanford, ²⁰¹⁷; Van Bourg et al., ²⁰²⁰; Yong & Ruffman, ²⁰¹⁴)	Dogs (Carballo et al., 2020; D'Aniello et al., ²⁰¹⁸; Katayama et al., ²⁰¹⁹; Sanford, ²⁰¹⁷)		Dogs (Carballo et al., 2020; Yong & Ruffman, ²⁰¹⁴)	Dogs (Sümegi et al., 2014)
Horses (Keeling et al., 2009)
Conspecific experiencing negative stimulation	Rhesus Macaques (Miller et al., 1959; Mirsky et al., ¹⁹⁵⁸; Wechkin et al., ¹⁹⁶⁴)	Rhesus Macaques (Miller, 1967; Miller et al., ¹⁹⁶⁶)	Chickens (Edgar et al., 2011; Edgar et al., ²⁰¹²; Edgar et al., ²⁰¹³; Edgar & Nicol, ²⁰¹⁸)		Rats (Twining et al., 2017; Yusufishaq & Rosenkranz, ²⁰¹³)
Rats (Church, 1959; Han et al., ²⁰²⁰;; Rice, ¹⁹⁶⁴; Twining et al., ²⁰¹⁷; Yusufishaq & Rosenkranz, ²⁰¹³)
Mice (Allsop et al., 2018; Atsak et al., ²⁰¹¹; Carrillo et al., ²⁰¹⁵; Chen et al., ²⁰⁰⁹; Gonzalez‐Liencres et al., ²⁰¹⁴; Jeon et al., ²⁰¹⁰; Jeon & Shin, ²⁰¹¹; Keum et al., ²⁰¹⁶; Keum et al., ²⁰¹⁸; Pisansky, Young, et al., ²⁰¹⁷; Pisansky, Hanson, et al., ²⁰¹⁷; Sanders et al., ²⁰¹³; Ueno et al., ²⁰²⁰; Ueno et al., ²⁰²⁰ (video)) (Sehoon Keum et al., 2018)	Chickens (Edgar et al., 2011; Edgar et al., ²⁰¹²; Edgar et al., ²⁰¹³)	Deer mice (Kavaliers et al., 2003)	Mice (Allsop et al., 2018; Chen et al., ²⁰⁰⁹; Ito et al., ²⁰¹⁵; Jeon et al., ²⁰¹⁰; Pisansky, Young, et al., ²⁰¹⁷)
Pigeons (Watanabe & Ono, 1986)	Pigs and Sheep (Anil et al., 1996; Anil et al., ¹⁹⁹⁷)	Deer mice (Kavaliers et al., 2003, 2005)
Chickens (Edgar et al., 2011; Edgar et al., ²⁰¹²; Edgar et al., ²⁰¹³; Edgar & Nicol, ²⁰¹⁸)	Pigs and Sheep (Anil et al., 1996; Anil et al., ¹⁹⁹⁷)	Degus (Lidhar et al., 2017)
Pigs and Sheep (Anil et al., 1996; Anil et al., ¹⁹⁹⁷)
Conspecific in pain	Rats (Li et al., 2014)			Rats (Li et al., 2014)			Rats (Du et al., 2020; Li et al., 2018; Li et al., ²⁰¹⁴; Lü et al., ²⁰¹⁷)
Mice (Langford et al., 2006; Martin et al., ²⁰¹⁵)	Mice (Du et al., 2020; Langford et al., ²⁰⁰⁶; Martin et al., ²⁰¹⁵)
Fearful demonstrator	Rhesus macaques (Miller et al., 1959) (pictures)				Mice (Bredy & Barad, 2009; Nowak et al., ²⁰¹³; Panksepp & Lahvis, ²⁰¹⁶)
Rats (Jones et al., 2014; Jones & Monfils, ²⁰¹⁶; Kim et al., ²⁰¹⁰; Knapska et al., ²⁰¹⁰; Pereira et al., ²⁰¹²)	Rats (Bruchey et al., 2010; Jones et al., ²⁰¹⁴; Jones & Monfils, ²⁰¹⁶; Knapska et al., ²⁰¹⁰)
Prairie voles (Burkett et al., 2016)
Agonistic interactions of conspecifics	Chimpanzees (Kano et al., 2016) (video, playback)	Chimpanzees (Kano et al., 2016) (video, playback)	Chimpanzees (Parr & Hopkins, 2000) (video) (Kano et al., 2016) (video, playback)	Chimpanzees (Kano et al., 2016) video, playback	Rats (Patki et al., 2014)
Rats (Carnevali et al., 2017; Finnell et al., ²⁰¹⁷^,²⁰¹⁸, Patki et al., 2014, 2015)	Rats (Carnevali et al., 2017; Finnell et al., ²⁰¹⁷^,²⁰¹⁸)	Rats (Carnevali et al., 2017; Finnell et al., ²⁰¹⁷^,²⁰¹⁸, Patki et al., 2014, 2015)
Mice (Iñiguez et al., 2018; Li, Xu, & Wang, ²⁰¹⁸; Miao et al., ²⁰¹⁸; Warren et al., ²⁰¹³^,²⁰¹⁴)	Greylag geese (Wascher et al., 2010)	Mice (Iñiguez et al., 2018; Warren et al., ²⁰¹³^,²⁰¹⁴)
Aggressive vocalizations of conspecifics			Chimpanzees (Dezecache et al., 2017)
Conspecific experiencing a negative event	Tufted capuchin monkeys (Morimoto & Fujita, 2012)	Horses (Trösch et al., 2020)		Pigs (Reimert et al., 2013, 2015)		Ravens (Adriaense et al., 2019)
Pigs (Reimert et al., 2013, 2015)
Horses (Trösch et al., 2020)
Conspecific experiencing a positive event	Tufted capuchin monkeys (Morimoto & Fujita, 2012)	Horses (Trösch et al., 2020)		Pigs (Reimert et al., 2013, 2015)		Ravens (Adriaense et al., 2019)
Pigs (Reimert et al., 2013, 2015)
Rats (Kashtelyan et al., 2014)
Horses (Trösch et al., 2020)
Positive interactions of conspecifics	Barbary macaques (Berthier & Semple, 2018)		Chimpanzees (Parr & Hopkins, 2000) (video)
Ravens (Osvath & Sima, 2014)
Positive vocalizations of conspecifics	Horses (Briefer et al., 2017)	Chimpanzees (Berntson et al., 1989)	Chimpanzees (Dezecache et al., 2017)			Rats (Saito et al., 2016)
Keas (Schwing et al., 2017)	Horses (Briefer et al., 2017)	Horses (Briefer et al., 2017)

Measures

Behavioral changes

Physiological and hormonal changes

Cognitive performance

Others

Stimulus^*

Temperature changes

Hormonal changes (cortisol, corticosterone)

Changes in memory/Learning

Cognitive bias

Changes in pain sensitivity

Stressed conspecific

Rhesus macaques

(Miller et al., 1963)

Pigs

(Goumon & Špinka, 2016)

Chimpanzees

(Parr & Hopkins, 2000) video

Prairie voles

(Burkett et al., 2016)

Prairie and meadow voles

(Burkett et al., 2016)

Rats

(Knapska et al., 2010; Mikosz et al., ²⁰¹⁵; Rogers‐Carter et al., ²⁰¹⁸)

Pigs

(Reimert et al., 2013, 2015)

Mice

(Ueno et al., 2020)

Asian elephants

(Plotnik & de Waal, 2014; Sharma et al., ²⁰²⁰)

Zebrafish

(Oliveira et al., 2017)

African elephants

(Douglas‐Hamilton et al., 2006; Schulte, ²⁰⁰⁰)

Pigs

(Goumon & Špinka, 2016)

Zebrafish

(Fernandes da Silva et al., 2019; Oliveira et al., ²⁰¹⁷)

Stressed conspecific (only auditory cues)

Mice

(Chen et al., 2009)

Chimpanzees (Berntson et al., 1989)

Horses

(Briefer et al., 2017)

Dogs

(Quervel‐Chaumette et al., 2016)

Rats

(Saito et al., 2016)

Dogs

(Huber et al., 2017; Quervel‐Chaumette et al., ²⁰¹⁶)

Goats

(Baciadonna et al. 2019)

Mice

(Chen et al., 2009)

Horses

(Briefer et al., 2017)

Cockatiels

(Liévin‐Bazin et al., 2018)

Goats

(Baciadonna et al. 2019)

Zebra finches

(Perez et al., 2015)

Zebra finches

(Perez et al., 2015)

Horses

(Briefer et al., 2017)

Stressed human

Dogs

(Carballo et al., 2020; Custance & Mayer, ²⁰¹²; D'Aniello et al., ²⁰¹⁸; Huber et al., ²⁰¹⁷; Sanford, ²⁰¹⁷; Van Bourg et al., ²⁰²⁰; Yong & Ruffman, ²⁰¹⁴)

Dogs

(Carballo et al., 2020; D'Aniello et al., ²⁰¹⁸; Katayama et al., ²⁰¹⁹; Sanford, ²⁰¹⁷)

Dogs

(Carballo et al., 2020; Yong & Ruffman, ²⁰¹⁴)

Dogs

(Sümegi et al., 2014)

Horses

(Keeling et al., 2009)

Conspecific experiencing negative stimulation

Rhesus Macaques

(Miller et al., 1959; Mirsky et al., ¹⁹⁵⁸; Wechkin et al., ¹⁹⁶⁴)

Rhesus Macaques (Miller, 1967; Miller et al., ¹⁹⁶⁶)

Chickens

(Edgar et al., 2011; Edgar et al., ²⁰¹²; Edgar et al., ²⁰¹³; Edgar & Nicol, ²⁰¹⁸)

Rats

(Twining et al., 2017; Yusufishaq & Rosenkranz, ²⁰¹³)

Rats

(Church, 1959; Han et al., ²⁰²⁰;; Rice, ¹⁹⁶⁴; Twining et al., ²⁰¹⁷; Yusufishaq & Rosenkranz, ²⁰¹³)

Mice

(Allsop et al., 2018; Atsak et al., ²⁰¹¹; Carrillo et al., ²⁰¹⁵; Chen et al., ²⁰⁰⁹; Gonzalez‐Liencres et al., ²⁰¹⁴; Jeon et al., ²⁰¹⁰; Jeon & Shin, ²⁰¹¹; Keum et al., ²⁰¹⁶; Keum et al., ²⁰¹⁸; Pisansky, Young, et al., ²⁰¹⁷; Pisansky, Hanson, et al., ²⁰¹⁷; Sanders et al., ²⁰¹³; Ueno et al., ²⁰²⁰; Ueno et al., ²⁰²⁰ (video)) (Sehoon Keum et al., 2018)

Chickens

(Edgar et al., 2011; Edgar et al., ²⁰¹²; Edgar et al., ²⁰¹³)

Deer mice

(Kavaliers et al., 2003)

Mice

(Allsop et al., 2018; Chen et al., ²⁰⁰⁹; Ito et al., ²⁰¹⁵; Jeon et al., ²⁰¹⁰; Pisansky, Young, et al., ²⁰¹⁷)

Pigeons

(Watanabe & Ono, 1986)

Pigs and Sheep

(Anil et al., 1996; Anil et al., ¹⁹⁹⁷)

Deer mice

(Kavaliers et al., 2003, 2005)

Chickens

(Edgar et al., 2011; Edgar et al., ²⁰¹²; Edgar et al., ²⁰¹³; Edgar & Nicol, ²⁰¹⁸)

Pigs and Sheep

(Anil et al., 1996; Anil et al., ¹⁹⁹⁷)

Degus

(Lidhar et al., 2017)

Pigs and Sheep

(Anil et al., 1996; Anil et al., ¹⁹⁹⁷)

Conspecific in pain

Rats

(Li et al., 2014)

Rats

(Li et al., 2014)

Rats

(Du et al., 2020; Li et al., 2018; Li et al., ²⁰¹⁴; Lü et al., ²⁰¹⁷)

Mice

(Langford et al., 2006; Martin et al., ²⁰¹⁵)

Mice

(Du et al., 2020; Langford et al., ²⁰⁰⁶; Martin et al., ²⁰¹⁵)

Fearful demonstrator

Rhesus macaques

(Miller et al., 1959) (pictures)

Mice

(Bredy & Barad, 2009; Nowak et al., ²⁰¹³; Panksepp & Lahvis, ²⁰¹⁶)

Rats

(Jones et al., 2014; Jones & Monfils, ²⁰¹⁶; Kim et al., ²⁰¹⁰; Knapska et al., ²⁰¹⁰; Pereira et al., ²⁰¹²)

Rats

(Bruchey et al., 2010; Jones et al., ²⁰¹⁴; Jones & Monfils, ²⁰¹⁶; Knapska et al., ²⁰¹⁰)

Prairie voles

(Burkett et al., 2016)

Agonistic interactions of conspecifics

Chimpanzees

(Kano et al., 2016) (video, playback)

Chimpanzees

(Kano et al., 2016) (video, playback)

Chimpanzees

(Parr & Hopkins, 2000) (video)

(Kano et al., 2016) (video, playback)

Chimpanzees

(Kano et al., 2016) video, playback

Rats

(Patki et al., 2014)

Rats

(Carnevali et al., 2017; Finnell et al., ²⁰¹⁷^,²⁰¹⁸, Patki et al., 2014, 2015)

Rats

(Carnevali et al., 2017; Finnell et al., ²⁰¹⁷^,²⁰¹⁸)

Rats

(Carnevali et al., 2017; Finnell et al., ²⁰¹⁷^,²⁰¹⁸, Patki et al., 2014, 2015)

Mice

(Iñiguez et al., 2018; Li, Xu, & Wang, ²⁰¹⁸; Miao et al., ²⁰¹⁸; Warren et al., ²⁰¹³^,²⁰¹⁴)

Greylag geese

(Wascher et al., 2010)

Mice

(Iñiguez et al., 2018; Warren et al., ²⁰¹³^,²⁰¹⁴)

Aggressive vocalizations of conspecifics

Chimpanzees

(Dezecache et al., 2017)

Conspecific experiencing a negative event

Tufted capuchin monkeys

(Morimoto & Fujita, 2012)

Horses

(Trösch et al., 2020)

Pigs

(Reimert et al., 2013, 2015)

Ravens

(Adriaense et al., 2019)

Pigs

(Reimert et al., 2013, 2015)

Horses

(Trösch et al., 2020)

Conspecific experiencing a positive event

Tufted capuchin monkeys

(Morimoto & Fujita, 2012)

Horses

(Trösch et al., 2020)

Pigs

(Reimert et al., 2013, 2015)

Ravens

(Adriaense et al., 2019)

Pigs

(Reimert et al., 2013, 2015)

Rats

(Kashtelyan et al., 2014)

Horses

(Trösch et al., 2020)

Positive interactions of conspecifics

Barbary macaques

(Berthier & Semple, 2018)

Chimpanzees

(Parr & Hopkins, 2000) (video)

Ravens

(Osvath & Sima, 2014)

Positive vocalizations of conspecifics

Horses

(Briefer et al., 2017)

Chimpanzees (Berntson et al., 1989)

Chimpanzees

(Dezecache et al., 2017)

Rats

(Saito et al., 2016)

Keas

(Schwing et al., 2017)

Horses

(Briefer et al., 2017)

Horses

(Briefer et al., 2017)

Stimulus: Stressed conspecific/human: exposure to a human or a conspecific which is under stress; Stressed conspecific (only auditory cues): exposure to the sounds emitted by a conspecific under stress; conspecific experiencing negative stimulation: exposure to a conspecific which, in that moment, is receiving painful stimulation (the aversive stimulus is present); conspecific in pain: exposure to a conspecific that has been subjected to a treatment inducing pain (e.g., injection of venom) (the aversive stimulus is not present); fearful demonstrator: exposure to a conspecific which is frightened due to a previous treatment; agonistic interactions of conspecifics: exposure to two or more conspecifics interacting in an agonistic manner (e.g., fights); aggressive vocalizations of conspecifics: exposure to aggressive vocalizations of conspecifics; conspecific experiencing a negative event: exposure to a conspecific being subjected to an unpleasant event, without causing harm or fear in the individual (e.g., frustration); conspecific experiencing a positive event: exposure to a conspecific enjoying a pleasant situation; positive interactions of conspecifics: exposure to two or more conspecifics interacting in a positive way (e.g., play); positive vocalizations of conspecifics: exposure to vocalizations emitted by conspecifics during positive situations (e.g., play).