The Gaze Communications Between Dogs/Cats
Dogs (Canis familyis) and cats (Felis silvestris catus) have been domesticated through various processes. Dogs were the first domesticated animals and cooperated with humans in hunting and guarding. Cats, by contrast, were domesticated as rodent predators and lived near human dwellings when humans settled and began farming. Although they have different ancestry, both have been widely integrated into human society and have exerted a great influence. In this review, we focus on ``gaze'', which is an important signal for humans, and discuss the communication function of dog and cat gaze behavior with humans. I will explain how the function of gaze influences the formation of mutual emotional connections, or "bonds," beyond communication. Finally, we present research approaches to the multimodal interactions between dogs/cats and humans involved in communication and bond formation. Domestication of Dogs and CatsDogs (Canis familiais) and cats (Felis silvestris catus) are the closest animals to humans. Domesticated about 15,000 years ago, dogs were the first animals domesticated from wild breeds (Freedman and Wayne, 2017). They gained social tolerance for humans and cooperated with them by assisting in hunting and guarding. Dogs were initially selected for their reduced stress response to humans and then for their usefulness in cooperating with humans (Driscoll et al., 2009). Wolves (Canis lupus), which share a common ancestry with dogs, have developed greater cooperative abilities than dogs, but wolves show only intraspecific cooperation. By contrast, cats were domesticated about 10,000 years ago. The main reason is that cats are rodent predators (Vigne et al., 2004). Moreover, cats were not artificially selectively bred. The ancestor of cats is the wildcat (Felis silvestris lybica), which, like most other felines, is a solitary and territorial animal (Bradshaw, 2016).Although dogs have a different ancestry than cats and were domesticated through different processes, they are the most common animals that live with humans (Figure 1). The basis of this coexistence is nonverbal communication. They use smell, hearing, touch, and sight to communicate with humans. Dogs and cats are sensitive to gaze, which humans use as a means of non-verbal communication. This review presents the communicative function of eye gaze in dog-human and cat-human interactions in recent studies (Table 1). Next, I will discuss bond formation beyond communication and the importance of eye gaze in bond formation. Finally, we discuss the possibility that other senses contributed to the bond formed between dogs/cats and humans, and research approaches to multimodal interactions that facilitate communication and bond formation. Comparing how dogs and cats interact with humans provides insight into how both species were integrated into human society. In other words, the differences between dogs and cats may result from differences in the social disposition and domestication process of their ancestral species. It may be due to change. With these considerations in mind, let's review our findings so far.Gaze Communication in Dogs Gaze direction in cooperative hunting wolves can be easily determined from their eye type. Furthermore, wolves have developed behaviors to send and receive gaze signals (Ueda et al., 2014). These results suggest that wolves use gaze to communicate with others. It is possible that the ancestors of dogs inherited this function and dogs applied it as gaze-based communication in their interactions with humans.When a dog receives a human gaze, it changes its behavior depending on the direction. For example, dogs underwent a series of trials in which they were prohibited from eating visible food (Call et al., 2003; Kaminski et al., 2013). Dogs retrieved food less frequently when humans saw them than in conditions where humans did not see them. Schwab and Huber, 2006). Dogs detect human attention states from the direction of their gaze. This behavior is necessary for dogs to respond to human commands, such as when hunting. Additionally, dogs expect what humans can see and change their behavior accordingly. For example, in one experiment, two toys were placed in a room, one of which he blocked with an opaque panel so that humans could not see it. Dogs were able to see both toys, but chose the one that appeared human when commanded to "fetch" (Call et al., 2003). In another experiment that observed free behavior in dogs, the duration of attention-seeking behaviors (such as whining, whining, and looking at the owner's face) in dogs increased in response to the owner's gaze (Ohkita et al. ., 2016). This ability to perceive someone else's point of view could be useful in cooperative human-canine hunting.Dogs are more likely to choose food from people who see them than from people who don't (Gácsi et al., 2004). This tendency may have been acquired early in the domestication process. Dogs often exhibit more hesitant behavior when approached by blindfolded humans, but will beg for food from sighted humans (Gácsi et al., 2004). This difference indicates that dogs discriminate between humans who are willing to give food and humans who are not, based on gaze, and will receive food from the former when allowed to eat. Food, and knowing if someone is giving food, was an important factor in the early domestication of dogs.Dogs, even puppies, use human cues such as pointing (Miklosi et al., 2005) and gaze with pointing (Hare et al., 2002). One study found that dogs were able to use human pointing and gaze direction to easily select one of two containers in which food was hidden. chimpanzees, who are human, find it difficult to use human cues on this task. Moreover, the dog's gaze only follows the human gaze (Hare et al., 1998; Agnetta et al., 2000; Téglás et al., 2012; Met et al., 2014). They look in the direction the human gaze (with head movement) is pointing. Dogs follow your movements as well as your gaze. If he had two bowls of food, the dog followed the bowl that humans did more under certain conditions (Nagasawa et al., 2020). Dogs chose the same containers they saw humans pick, even when they saw humans picking up food and pretending to eat it (Chijiiwa et al., 2020). Following human behavior, including gaze, would have aided dog-human cooperation for hunting and gathering before humans began to establish cultures based on farming and settlement.Dogs show social referencing by seeing and using other people's facial expressions and actions in unfamiliar situations. In unsolvable tasks where they do not have access to food, they see the owner (Miklosi et al., 2005), whereas Lazzaroni et al. (2020). Even when encountering a strange object such as a fan with some ribbons on it, most dogs seem to refer to the owner after seeing the strange object (Merola et al., 2012a,b). . This alternating gaze is thought to have a function of joint attention, directing the other's gaze to an object in order to obtain cooperation in problem solving. In humans, alternating gazes followed by joint attention are thought to be related to intent identification and reference establishment (Emer, 2000). Dogs can also use their own gaze to guide the human gaze. The function of a dog's alternating gaze from an object to a person is unknown, but dogs may ask for help in situations when they are unsure of what to do or cannot solve a problem on their own. Recent studies suggest that dogs' gaze behavior toward humans is influenced by their life experiences (Marshall-Pescini et al., 2017; Brubaker et al., 2019). Therefore, both domestication and socialization influence the gaze behavior of dogs towards humans.Cat Gaze Communication Cat ancestors lived alone. Therefore, species that hunted in groups may not have needed the ability to read other individuals' gazes as much as they did. Recently, however, there have been reports of communication between cats and humans through their gaze. Cats detect human gaze by head movements and change their behavior accordingly (Koyasu and Nagasawa, 2019). When a familiar human (experimenter) and a cat spent time in the same room, the behavior of the cat was observed in response to the familiar human's gaze. Cats spend less time looking at familiar humans when they are gazed at than when they are not gazed at, and unlike dogs, they show behavior to avoid familiar gazes. was suggested. Cats may equate human gaze with cat gaze, indicating threat in social situations where there is no goal or threat (Bradshaw, 2016). However, in a study on feeding status, cats were fed by humans who stared at them (Ito et al., 2016). Similar to Gácsi et al. (2004), two humans behaved differently in the presence of cats. I chose many. Whether cats avoid/select gazes may depend on experimental circumstances. Cats also use human signals (Miklosi et al., 2005). No statistically significant performance was found between dogs and cats when it came to human pointing ability.Additionally, cats can follow human gaze (Pongrácz et al., 2019). In the interactive food-choice situation, cats followed human gaze (head movements) in about 70% of trials. In the condition of choosing one out of two food bowls, the cats followed human movements as well as eye gaze. Similar to dogs, cats followed humans to visit containers even after they saw humans removing food and pretending to eat it (Chijiiwa et al., 2020). Cats became part of human society to catch mice, but they didn't have to play any other role. Today, cats depend on humans for food, so they likely acquired these abilities during development. regardless of their susceptibility to human behavior in situations involving food. Cats, unlike dogs, did not exhibit social referencing behavior in unsolvable tasks in the feeding context (Miklosi et al., 2005). Cats may use the cues provided, but never request the cues themselves. They didn't rely on others for food, so they don't demand cues from themselves. However, in some situations cats exhibit social references (Merola et al., 2015). When we showed cats a paper fan with a ribbon attached, 80% of them stared alternately at the paper fan and their owner, but their behavior changed according to human emotional expressions. Cats can read human expressions and actions, and guide human gaze to objects when they encounter something unfamiliar and don't know what to do. Given the domestication process, these results could be attributed to cats' lack of history of cooperating with humans to acquire food.Therefore, cats avoid/select gazes and show/do not show social references, depending on the social context. Although the factors that drive this may become apparent, there is no doubt that cats use their gaze to communicate with humans. Cats did not originally need gaze function, but it is thought that it evolved during their lives with humans.Bonding between dogs/cats and humans Dogs/cats can distinguish signals based on human emotions. Dogs change their behavior depending on the human emotional state. In one study, dogs sniffed, snorted, and licked humans pretending to cry (Custance and Mayer, 2012). In the social her reference experiment mentioned above, dogs approached the unfamiliar fan when the owner responded positively and moved away when the owner responded negatively (Merola et al., 2012b). Dogs also distinguished human emotional states and facial expressions (Nagasawa et al., 2011; Buttelmann and Tomasello, 2013; Turcsán et al., 2015). Similarly, cats change their behavior according to human emotional states. Cats rub their owners more often when their owners are depressed (Rieger and Turner, 1999). Studies have shown that a cat's behavior toward its owner during interactions is influenced by the owner's emotional state (Turner and Rieger, 2001). Similar to dogs, they distinguished between human facial expressions and their associated postures (Merola et al., 2015; Galvan and Vonk, 2016) and stranger voices (Quaranta et al., 2020). Dogs/cats are able to distinguish between signals based on human emotions, providing a foundation for forming emotional bonds.Previous research has also suggested that an emotional bond exists between dogs/cats and humans. To investigate whether emotional bonds are formed, animals exhibit 1) emotional or behavioral responses to specific individuals, and 2) stress responses to separation, and stress-reducing/pleasant behaviors upon reunion. We need to know if (DeVries, 2002). The Ainsworth Strange Situation Test (SST) is widely used to demonstrate bonding with primary caregivers in infants, dogs and cats. In the new environment, dogs' exploratory and playful behaviors increased when their owner was in the room compared to when there were only strangers in the room, and when the owner left the room, strangers left the room. Following behavior was increased in dogs compared to sedation (Topal et al., 1998). This observation implies that dogs behave differently towards their owners than to strangers. Its owner acts as a secure base, much like the human mother-child bond.Gaze plays an important role in forming these human-canine bonds. In an experiment that observed dogs' free behavior in response to human gaze, attention-seeking behavior in dogs increased when owners looked at them (Hare et al., 2002). Increased attentional alertness in dogs when receiving a human gaze could be an attachment signal that draws the owner to the dog. Furthermore, a dog's gaze directed at its owner led to an increase in owner's oxytocin secretion (Nagasawa et al., 2009). The oxytocin neuroendocrine system is associated with the promotion of uterine contractions and milk secretion during childbirth and plays an important role in postnatal maternal behavior (Nagasawa et al., 2012). The dog's gaze increased owner-dog interaction and increased oxytocin secretion in dogs. In other words, there is a positive loop of oxytocin-mediated bond formation that is facilitated and regulated by human and dog gaze, as in mothers and infants (Nagasawa et al., 2015).The cat-owner bond is a form of attachment similar to that between dogs or infants and their caretakers (Edwards et al., 2007). The SST has shown that cats spend more time moving/exploring when in the company of their owners and have higher frequencies of vigilant behavioral events when in the company of strangers. A study that re-examined these bonds using a crossover design experiment with modifications that improved and counteracted the SST, found that more people were affected when the owner left the room than when the stranger left the room. Cats were louder (although there was no other evidence of a safe base) (Potter and Mills, 2015). Recently, a secure-based test (SBT) was conducted to investigate whether humans function as attachment objects for cats (Nagasawa et al., 2009). It turns out that the bond between cats and humans is similar to the bond between mothers and dogs and humans. However, the lack of evidence that the bond was to a specific individual warrants additional experiments with strangers. There were proximity-seeking, separation distress, and reunion behaviors, indicators of attachment relationships between cats and caretakers. As indicated, there is some evidence of a cat-human bond. However, it is unclear whether gaze promotes bond formation as it does in dog-human relationships. Cats also communicate via gaze, especially with humans, so gaze may be an important factor in bonding.An unconscious signal, blinking, may also play a role in mutual gaze that facilitates bond formation. One study reported that blinking is synchronized between dogs and humans during mutual gaze (Koyasu et al., 2020). The dog blinked about 1 second after the owner or stranger blinked. The owner blinked immediately after the dog blinked, and the stranger blinked after the dog blinked a little later. Although there is some time lag, the existence of mutual blink synchronization was suggested. A similar phenomenon was observed in cats. This synchronization is believed to lead to mutual understanding and effective communication between humans. Getting the same physiology as others in sync can also lead to mutual understanding and effective communication between dogs and cats. These results suggest that similar communication signals evolved in humans, dogs and cats. However, individual differences exist, especially personality. By spending time together in the house, dogs, cats and humans are thought to be able to learn communication unique to pairs and groups and form bonds with specific individuals. Bonding is more beneficial to dogs and cats in that it leads to more food, better food and greater safety, and it is more beneficial to humans in that it reduces stress and anxiety and makes them healthier. Therefore, interspecies bonding benefits both sides.Voices and scents that deepen tiesSince dogs and cats use different types of integrated senses to distinguish between humans, other senses, such as hearing and smell, may also contribute to bond formation. perceptual information may facilitate bond formation. Cats have adapted their voices to communicate more effectively with humans. For example, adult cats meow at humans (Mertens and Turner, 1988), but meowing is typically used only for communication between kittens and their mothers (Bradshaw and Cameron-Beaumont, the year of 2000). Furthermore, domestic cat meows are more pleasing to humans than wildcat meows (Nicastro, 2004), and feral cat meows differ from domestic cat meows in the acoustic variables shown in the spectrogram (Yeon et al., 2004). 2011). Another example is that cats purr more when reuniting with their long-lost owners (Eriksson et al., 2017). Purring is a common sign of gratification or care-seeking behavior (McComb et al., 2009). Purring can occur in a variety of settings (Merola and Mills, 2016), but is most commonly seen in kittens seeking care from their mothers (Bradshaw and Cameron-Beaumont, 2000). Domestication and socialization are thought to have led to the development of vocal communication in cats with humans. Cats are also sensitive to human vocalizations. Cats distinguish between owner's voice and stranger's voice (Saito and Shinozuka, 2013). Cats participating in the habituation/disfamiliarization test showed decreased responses to sustained stranger voices and increased head and ear movements to hearing the owner's voice. Dogs also recognize their owners' voices (Adachi et al.,Cats also have highly developed olfactory communication. Most small felines, including the cat's ancestor, Felis silvestris lybica, have exclusive territories. Species with large territories rarely meet other species and tend to communicate by smell. Some cats live in homes with multiple cats or in dense urban environments. Group cats sometimes use their sense of smell to distinguish between group members and non-group members. Cross-infection between individuals during allorubbing or while marking joint scent posts increases the similarity of odor profiles between members of a social group, although it has not been conclusively demonstrated (Gittleman, 2013). Therefore, olfactory communication in cats may be more complex than in other felines. They also communicate with humans through smell to demonstrate rubbing behavior. The fact that cats are adept at communicating through their sense of smell supports the relationship between cat rubbing and social bonding. Smell helps dogs distinguish between owners and strangers. The caudate nucleus region of the dog's brain is more strongly activated when exposed to familiar human odors compared to familiar dog, unfamiliar dog, unfamiliar human, and one's own odors. , suggesting positive emotional responses to familiar human odors (Berns et al., 2015). Dogs can also distinguish human emotions with their sense of smell. Dogs showed higher cardiac activation when smelling human fear chemical signals than when neutral (Siniscalchi et al., 2016). Dogs also display similar emotional responses to others through their sense of smell (D'Aniello et al., 2018) and act accordingly.Additionally, dogs and cats generate visual images when they hear vocalizations (Adachi et al., 2007; Takagi et al., 2019). Such an exchange of information between sensory modalities may be useful for animals, as available modalities may not be available at other times. Additionally, individuals are identified by several senses such as appearance, voice, and smell. The contribution of auditory and olfactory communication to bond formation should be investigated in future studies.CONCLUSIONS Both dogs and cats have integrated into human habits to improve access to food, using human signals to obtain information such as food location. However, they have different food acquisition situations. Dogs exhibit behaviors that require human cooperation, whereas cats, due to the nature of their ancestral species, are not dependent on humans. Dogs initially worked with humans as working animals, and cats were allowed to catch mice in human habitats. Today, however, cats and dogs share an equal and similar ecological niche among humans. Of particular interest is the ability of cats, originally solitary animals, to live in groups with humans and other cats. Most of the behaviors that cats exhibit toward humans were initially observed in their mother's kittens, suggesting that the behaviors seen in group adaptations with humans are inherent. In the future, cats may acquire more dog-like abilities through human selection, such as a more consistent and expressive gaze. Investigating the changes that cats may exhibit through selection will help us understand the evolutionary process of sociality in a broader context.Dogs and cats use a variety of senses to communicate with humans . increase. Each of these senses contributes to the distinction between owner and stranger. Voices, smells and other factors also facilitate bond formation between dogs/cats and humans. Future research should explore other perceptions that may have been involved in bond formation as well. may have provided the basis for a mutually beneficial coexistence with Author contributions HK, TK, ST, and MN wrote the manuscript. All authors contributed to the article and approved the submitted version. fundraisingThis work was supported by the Japan Society for the Promotion of Science, and the Japanese Ministry of Education, Culture, Sports, Science and Technology Grants-in-Aid for Scientific Research (#20J14760 to HK, #19H00972 to TK). #17J08974 to ST, #18H02489 and #19K22823 to MN). Conflicts of interest The authors declare that their research was conducted in the absence of any commercial or financial relationship that could be construed as a potential conflict of interest.References Kaoru Adachi, Hiroshi Kuwahata, Ken Fujita (2007). 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