**2. Methods**

*Types of Nonverbal Communication*

ments such as online social media [2].

characteristics through the anthropomorphic animal stickers.

embedded in a verbal message or used on its own.

equivalent to "biaoqing" (the Chinese words for indicators of social expressions) [1]. One can use stickers to express our thoughts, emotions, intentions and stances on WeChat. Using stickers can complement the lack of human nonverbal cues (e.g. human facial and vocal expressions) in communications under virtual environ-

The character of the sticker can be a person, but is often a non-human character with anthropomorphic (or human-like) features (which can be animals or other human-created cartoon characters). It is intriguing how communicators evaluate interpersonal meanings delivered by the sticker users and the associated personal

As a typical way to create a virtual character, anthropomorphism is a process of assigning human identity and human personality to non-human objects [3] and has extended from religious divine targets to animals, naturally occuring objects, and robots [4]. Anthropomorphism makes the target more vivid, affective and human like, which is an effective communication tool [5]. The anthropomorphic image is more attractive because we are familiar with human-like animals or other targets [6]. Therefore, anthropomorphic stickers are well seen in social media and is often

Evidence has already shown that stickers can ease interpersonal interactions in virtual environments, complement textual information exchange, and facilitate the expression of emotions and communicative meanings [2]. Adding anthropomorphic features to stickers can further enhance their ability to represent the speaker's emotions, attitudes and thoughts, and serve as an effective cue for the perceivers to understand the speaker's message, given that humans have the tendency to understand the non-human character with their knowledge of how to communicate to humans [7]. In addition to the inclusion of anthropomorphism, categories of non-human objects may impact the human perception of stickers. In the WeChat sticker store, most stickers are animals or animal cartoons. Psychological studies have revealed the emotional bondings between the human and the animals, and showed that humans displayed empathy and attitudes towards animals [8, 9]. The relationship between human perceivers and stickers with animal characters is therefore worthy of attention. Humans hold different stereotypical opinions towards different kinds of animals which is often culturally-specific [10, 11]. For example, dogs and pigs are typically associated with a positive stereotype of commitment and faithfulness and rabbits are typically associated with a negative stereotype of timidness in the Chinese culture. Dogs were perceived cuter than cats and humans and attracted different frequency and length of lookings than humans [12]. In WeChat, stickers have different representations of animal characters and can be categorized in cartoons or in real forms. It is shown that the contextual reality of a picture in different presented forms affected the perceptual outcome and its neural responses that were related with empathy, with the pictures showing a stronger activity than the cartoon ones [13]. The facial expressions of different presented forms altered the perceiver's neural responses, with the real expression eliciting a response in the relatively late stage of evaluating the emotional value of the stimuli whereas the cartoon expression eliciting a stronger response indexing the face recognition [14]. These findings are not sufficient in informing us about how a cartoon or a real form of animal could modulate the associated evaluative outcomes when they are the

Moreover, the expressions encoded by the characters may affect human perception of stickers. Studies on Weibo have documented the capacity of encoding emotional and social expressions in stickers and online tools to perform sentiment analysis such as MoodLens to decode emotions conveyed in the emoji [15]. The perceived cuteness of anthropomorphic animal stickers can be affected by different

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targets of the stickers.

#### **2.1 Participants**

Twenty-one students who aged 18-35 years old were recruited via WeChat advertisements and the campus forum from Tongji University in China (Gender: 11 females; Age: 21.3 ± 2.12 years). They comprise a wide variety of academic majors and none reported to have suffered from any psychotic or neurological disorders. All participants were given informed consent before the study and each was compensated 30 RMB for their participation. The study was approved by the Ethics Committee of Tongji University.

#### **2.2 Material**

One hundred and twenty animal stickers were selected from the "Store of Expression" on the WeChat which provides many sticker packages for people to use in chat. A sticker package normally consists in stickers of different expressions and features of one animal character. Typically, the intended expression of each sticker was labeled a key word in each package. For example, the sticker package called *mitaomao* by *bujuexiaoxiao* has 24 stickers with different expression, and its character is a cat. The expression types were the most commonly used on WeChat and twelve expressions were pre-selected by the authors after they screened 59 animal sticker packages. These social expressions represented typical communicative meanings in interpersonal interaction each of which served a certain pragmatic function (i.e. agreement, commitment, refusal, having fun, greeting, gratitude), or emotional function (i.e. shyness, fear, happiness, sadness, anger, and grievance). These expressions were either labeled by the creator of the sticker and validated by the authors. Each expression was further represented by five animal kinds (cat, dog, pig, duck, rabbit) in two forms (cartoon, real). These five animal kinds were selected as the most common kinds in stickers. All stickers were adjusted into the same size (250 × 250 pixels). All was in static form and contained verbal messages on the stickers (see **Figure 1** for the demonstration of a set of stickers to express agreement). Verbal messages were all Chinese words except for the stickers of a greeting expression.

**Figure 1.** *Exemplar stickers that express intended agreement by five kinds of animals in both cartoon and real forms.*
