The Influence of Prior Expectations of a Robot’s Lifelikeness on Users’ Intentions to Treat a Zoomorphic Robot as a Companion

One of the most powerful predictors of whether any two given people will be friends is their proximity. Randomly assigned college roommates, who are thereby forced into frequent interactions, are far more likely to become good friends than enemies [77]. Proximity, or, more precisely, functional distance, is a powerful predictor of liking. Functional distance is a measure of how often people’s paths cross. When two individuals are in a ‘closed field’ situation in which people are forced to spend time together, such traveling on the same bus each morning, the environment itself causes these people to notice each other [61]. However, why does proximity breed liking? One relevant factor is availability; obviously, one has fewer opportunities to get to know someone whose path one is unlikely to cross. Proximity enables people to discover commonalities and exchange rewards. Proximity also leads to liking for another reason: mere exposure to any novel stimuli enhances people’s ratings of them. The mere-exposure effect refers to this tendency for novel stimuli to be evaluated more positively after the rater has been repeatedly exposed to them. A meta-analysis shows that the mere-exposure effect is robust and reliable [18]. Proximity is rewarding. It costs less time and effort to receive the benefits of friendship with someone who lives or works close by. Proximity also creates an opportunity for acquaintance.

However, proximity is not sufficient for the establishment of human friendships. When two people are in not a closed environment but an ‘open field’ situation, such as a bus station, there are other factors that cause one to notice the other [13]. One such factor is physical attraction, namely, a positive evaluation of the physical appearance of another [15]. There are many research studies demonstrating the importance of physical appearance, which is regarded as a crucial factor in determining first impressions of other people [20]. This is explained by the ‘what is beautiful is good’ paradigm [32], which refers to the presumption that physically attractive people (or things) also possess other socially desirable traits. To say that attractiveness is important, other things being equal, is not to say that physical appearance always outranks other qualities. However, first impressions are important and are becoming more so as societies become increasingly mobile and urbanized and as contacts with other people become more fleeting [68]. We like attractive people because we associate them with other desirable traits [1, 55].

Given that two people do come to know one another, further factors will influence whether their acquaintance develops into a friendship. The factors that determine initial attraction are different from those that determine prolonged friendship [29]. The cues related to friendship formation are considered to shift from physical characteristics to those immediately concerned with more cognitive attributes [28]. This is when people begin to select those individuals with whom friendship is assumed to have a positive appeal. This is also the stage at which one concerns oneself with means of describing the other’s personality and personal characteristics. Each individual also evaluates the other’s personality in terms of its overlap with that individual’s own personality, i.e., their similarity.

The formulation of the similarity-attraction hypothesis is drawn from Newcomb’s [77] well-known paper on the prediction of interpersonal attraction. In this hypothesis, similarity (real or perceived) of personality is considered to be a major determinant of likeability and friendship choice [70]. Since Newcomb’s discovery, research has repeatedly demonstrated that the more similar someone’s attitudes are to one’s own, the more likeable one will find that person. Likeness generates liking. Research on liking and attraction has shown that we tend to like others who are similar to us [4] because they provide us a source of validation for ourselves. This provides the basis for the next precondition for human friendship formation, reciprocal liking.

Proximity and attractiveness influence one’s initial attraction to someone else, and the discovery of similarities helps people to progress through the various stages of relationship development [74, 99]. Similarity between attitudes, in particular, is related to reciprocal liking [4, 20, 77]. If others have similar opinions, we feel rewarded because we presume that they like us in return [90]. The phenomenon of reciprocal liking is grounded in Heider’s [48] balance theory: we like those who like us, or those who like the same things that we like (one of which is ourselves). Thus, liking is typically mutual, i.e., reciprocal liking. However, reciprocal liking depends not only on one believing oneself to be likable [51] but also on the sequence in which liking and disliking may have been expressed [3]. Furthermore, not only the liking itself but also the reasons for it are subject to interpretation [51]. The explanatory power of reciprocal liking seems, therefore, to have its limitations.

Reciprocal liking also occurs when people interact with technologies. People who have been flattered by their computers report more positive affect, better performance, more positive evaluations of the interaction, and more positive regard for the computers [88]. Flattery can thus be an effective strategy for social robots to encourage their users to like them. For example, in the studies of Leite and colleagues [59, 60], it was found that children preferred to receive esteem support (i.e., reinforcement of the other’s sense of competence) from the robots with which they interacted and evaluated those robots that provided positive feedback more positively.

Researchers agree that intimacy is essential for many human friendships [58], such as human friendships. Intimacy results from a dynamic, interpersonal process in which both self-disclosure and partner responsiveness are key components [89]. Self-disclosure is the verbal communication of personally relevant information, thoughts, and feelings to another, and research on self-disclosure often relies on the degree or depth of self-disclosure as an index of intimacy [99]. In the context of self-disclosure, scientists have distinguished between factual and emotional disclosure [89]. Factual self-disclosures reveal personal facts and information, and emotional self-disclosures reveal one’s private feelings, opinions and judgments. Emotional self-disclosures are believed to create greater intimacy because they provide the listener with the opportunity to support and confirm core aspects of the discloser’s view of self [89]. Trust in the listener will enhance self-disclosure [47]. However, the assertion of a causal relation between self-disclosure and growing intimacy has been criticized [83]. It could be that a person may reveal private information merely to express him- or herself, to release tension, or to gain relational control, which does not necessarily imply that this individual is seeking or will achieve a more intimate bond with his or her partner.

Other researchers advocate the need to evaluate self-disclosure together with the level of partner responsiveness to assess the level of intimacy [11, 27]. Perceived partner responsiveness is the belief that a relationship partner understands, values, and supports important aspects of the self [89]. A positive evaluation of partner responsiveness leads to security and enjoyment, whereas a negative evaluation leads to anxiety and distress [47]. Therefore, an integrated model of intimacy has been developed by Reis and Shaver [89], who describe intimacy as the product of a transactional, interpersonal process whereby an individual discloses personal information, thoughts, and feelings to a partner; receives a response from that partner; and interprets that response as understanding, validating, and caring.

The integrated model of intimacy is supported by the principle of the depth of penetration from social penetration theory. The depth of penetration refers to the degree of intimacy, which increases when a human friendship develops to a more personal level. According to social penetration theory [99], self-disclosure is reciprocal. Vulnerability shown by an individual elicits trust, which, in turn, evokes a need for emotional equity that could be fulfilled by self-disclosure from that individual’s partner. Consequently, intimacy grows through interactions in which an individual discloses personal information, thoughts and feelings to a partner. In return, the partner responds in a way that is perceived by the individual as understanding, validating and caring.

The literature described here suggests that nonhumans play a more prominent and more active role in the interactions of humans with their social environments than previously acknowledged by sociologists [23]. Because people interact similarly with social interfaces as they do with other people [54, 88] and seemingly build relationships following the same rules as for human–human interactions [6, 16], it seems unnecessary to depart from these human–human interaction rules when evaluating human–robot interactions [57]. Therefore, it is assumed that there will be more similarities than differences between human–human interactions and human–robot interactions. Moreover, these similarities are needed to create meaningful interactions and relationships between humans and robots [26]. Thus, if these premises hold true in future human–robot interaction research, then the fundamentals of human–human interpersonal interactions should serve as the point of departure for the development and implementation of social behavior for robots.

The theory of the need to belong predicts that humans are, in principle, capable of bonding with robots given the precondition that these robots are sufficiently social to satisfy the needs of such a relationship with respect to regular and meaningful interactions [57]. People tend to ascribe human characteristics to nonhuman objects [88], and this challenges the restriction of meaningful social interaction to interactions with minded human beings. Certain interactionists, e.g., [91, 105], have argued that humans can project mind onto nonhumans—including animals, objects and images—seemingly endowing them with human capacities. Similarly, the process of the media equation allows humans to perceive nonhumans as viable others in social interactions. This make it irrelevant for nonhumans to actually possess the human capacities traditionally defined as critical for social interaction [23]. Overall, this reasoning argues for the inclusion of nonhumans in meaningful social interaction. Thus, robots endowed with capacities perceived by humans as social behavior could easily pass as legitimate partners in social interactions with humans.

However, considering that we used a zoomorphic robot in this study, we should also reflect on human–pet relationships. Using a robot with a zoomorphic embodiment has the advantage that the ‘uncanny valley effect’ can be better avoided [38]. The ‘uncanny valley effect’ is a hypothesis that predicts that robots with human-like characteristics look and act almost, but not perfectly, like actual human beings, causing a revulsion response in human observers [76]. Moreover, robots with an animal-like design rely on the assumption that familiar appearance and communication modes easily and effectively support human–robot interactions [92]. Robots with zoomorphic embodiments exhibit characteristics that are associated with domesticated animals and are designed to imitate those of living creatures to establish human–robot relationships, which are, in many ways, similar to owner–pet relationships [54]. Thus, it was desirable to use a robot with a zoomorphic embodiment in this study. Although humans and animals differ in many aspects, such as language, learning and culture, analogies with human–human interrelationship theories, such as attachment theory [2, 109], have nevertheless helped to explain a large number of human-pet attachment studies [90]. Moreover, the relationships people can form with their pets [2] show us that satisfying interspecies communication is possible. Thus, even though the robot used in this study was not humanoid but rather zoomorphic, we assumed that we could still build on theories of human–human relationships to explain why people are willing to treat a zoomorphic robot as a companion.

Because people exhibit similar behaviors of assigning humanlike attributes to robots as they do to other animals and objects, human–robot relationships—even with pet-like robots—might similarly develop. Indeed, there are several similarities in how we relate to animals and robots. These similarities suggest that among other things, it is the appearance of the robot or animal, and not their ontological status, that determines how we treat them. These similarities are related to how we perceive both types of entities in different contexts, such as their functionality in society and between societies or cultures [24]. Regarding functionality, both animals and robots appear in various roles. For example, we have multiple different relationships with animals: as companions or pets; as living meat, livestock, and production units or farm animals; as game for hunting; as wild animals; as experimental material in scientific experiments; and as entertainment in the zoo [45, 104]. Similarly, we treat robots differently depending on the different use contexts in which they appear. For example, we treat robots as slaves in an industrial context but can more easily perceive them as companions when they interact socially with us in our home environments. In addition to the use context, Coeckelbergh [24] notes the similarity of different views on animals and robots with regard to cultural differences. For example, in certain cultures, dogs are regarded as food, whereas in our Western society, dogs are treated as companions. Similarly, there seems to be a cultural difference in how cultures perceive robots [67]; Western countries appear to be dominated by slave models of robots, whereas Eastern countries are more familiar with treating robots as companions. Thus, the manner in which we relate to both animals and robots depends on their appearance. This means that how we regard both types of entities depends on our human perception, which, in turn, depends on personal, contextual and cultural categories [24]. Human–robot relationships should not be understood in relation to what the robot actually can or cannot do but should rather be approached in terms of how they appear to us and how we perceive them in these relationships.

Thus, it might be that social robots, even pet-like ones, are just as capable as other human beings of satisfying the human need to belong. So, there is a need for a further exploration of the role of robot companions in society and the value placed on relationships with them. Some researchers state that the ability to develop and maintain individual relationships may be a useful benchmark for human–robot interaction and that robots should be able to maintain relationships with people that are unique, individual, and personal [66]. Given that robots are predicted to increasingly serve in social roles for which some form of human–robot relationship would be beneficial, this study will investigate whether the preconditions for human friendship formation can explain why people may treat zoomorphic robots as companions.