## 2 Theoretical Background and Hypotheses
### Social Capital and Social-Support Activities  
Social capital refers to a set of actual and potential resources rooted in the relationships of an individual in a social unit [10]. On the other hand, researchers posit that social capital represents an environment of trust and shared resources of networks based on the social associations established in a voluntary manner [33; 34]. As such, social capital has been considered a vital factor that can drive people to engage in social exchange behaviors (e.g., knowledge contribution) [35]. Previous literature has found that people with more social relationships will be more likely to provide support in the context of social media [36]. Therefore, this study considered social capital as a factor that may determine individuals' social-support activities.  
Social capital is a complex construct that can be classified into different dimensions [10; 37; 38]. In general, three key aspects can be used to represent social capital: identification, trust, and norms [10; 35]. Identification occurs when individuals see themselves as being grouped with others in a social unit [38]. while trust is defined as one party's willingness to be vulnerable to the actions of another [6]. Norms, on the other hand, refer to the norms that facilitate an individual's behavior (e.g., knowledge sharing) in an organization [35]. In the context of social media, providing and receiving support are voluntary; therefore, norms may not be the major antecedent that determines users' social-support activities. The previous literature also agrees that social capital exists when people in a social unit experience strong identification and trust [30; 38]. Therefore, identification and trust can be recognized as the key dimensions of social capital. Furthermore, researchers have argued that a higher-order construct can be employed to provide a more coherent description of the multiple facets of a complex phenomenon [39; 40]. The previous literature has used second-order models to examine the influence of social capital on an individual's behavior, as well (e.g., [41]). Thus, we conceptualize social capital as a second-order construct that includes the dimensions of identification and trust.  
Social capital theory suggests that relationships embedded in a network create greater access to resources [42]. Thus, benefits could be extracted from these social relationships. The aspect of social capital has been used to explain various pro-social behaviors, such as knowledge sharing (e.g. [6; 43]) and offering social support [11]. Previous literature suggests that identification is essential in facilitating resource exchange in online settings (e.g., [8; 11; 44]. Strong identification will enable users to be concerned with the outcome of a social unit rather than their own efforts and losses [35]. Users in a social unit may display altruistic behaviors [11; 45] and act in the best interest of users in the social unit [11; 45; 46]. Therefore, it is expected that users with strong identification will be more likely to engage in social-support activities.  
In addition, trust is also crucial for motivating people to engage in cooperative interactions [10; 44; 46; 47] especially in an environment without workable rules to ensure others will behave in a socially acceptable manner [5], such as social media. The previous literature has also provided empirical evidence to support the effect of trust on getting help and giving help in the online context [4]. Based on the above arguments, we expect social capital to have a significant impact on online support activities.  
**Hypothesis 3 (H3)**.: _Social capital is positively related to receiving online support._  
**Hypothesis 4 (H4)**.: _Social capital is positively related to providing online support._