With the development of information technology, the Internet has played an important role in people’s lives. Especially during the COVID-19 pandemic, people have had to rely more on the Internet to maintain social contacts, work, and study because of family isolation. Compared to the end of 2019, China’s Internet traffic had increased by approximately 50% by mid-2020 [1]. However, the ever-increasing rate of Internet use is a double-edged sword that has brought convenience to our lives and is inevitably accompanied by deviant behaviors. Most notably, 34.5% of Chinese juvenile Internet users have encountered various kinds of undesirable Internet information, such as obscenity, bloody violence, self-mutilation, and suicide [2]. Therefore, online deviant behaviors have received increasing attention from researchers.

In the literature, online deviant behaviors usually refer to cyber delinquency, cyber deviance, or online deviance ^[3][4][5][3,4,5]. These are types of behaviors that refer to harming oneself or others because the individual is not adjusting well to the Internet environment through online flaming, deception on the Internet, and online obscenity and pornography ^[6][7][8][9][6,7,8,9]. Online deviant behaviors are closely related to academic failure, psychological crises, and criminal behaviors ^[7][10][11][7,10,11]. Given these adverse effects of online deviant behaviors, it is necessary to identify trigger factors and underlying mechanisms.

Previous studies have shown that individual factors (such as moral disengagement [12], self-control [13], interpersonal needs [14], etc.) and environmental factors (for example, Internet anonymity [13], social ostracism [15], family patterns [16], peer network deviant behaviors [17], etc.) are closely related to online deviant behaviors. However, less is known about the psychopathology-related variables among individual factors. Boredom is ubiquitous in human existence [18]; especially during the COVID-19 pandemic, boredom was reported as one of the most salient negative experiences [19]. Therefore, reswearchers explored the association between boredom and online deviant behaviors.

In previous studies, there have been two main aspects of boredom: state boredom and trait boredom. When boredom is experienced as a result of external circumstances, it is called state boredom, which is situation-dependent and transient [20]. State boredom is not intrinsically harmful but how a person responds to boredom can lead to either positive or negative consequences [21]. Additionally, the different ways to cope with boredom might depend in part on individual differences in boredom proneness. Boredom proneness is viewed as a trait, which affects an individual’s perception of environmental stimulation and persists through situational change ^[20][22][20,22]. Individuals with high boredom proneness are more likely to involve attentional and impulse control difficulties, which leads to momentary boredom and thus the negative consequences [23]. Following this reason, the current study focuses on boredom proneness.

According to sensation-seeking theory and arousal theory, people who maintain their health must be exposed to a variety of stimuli to achieve optimal arousal levels ^[22][24][22,24]. However, individuals with a high level of boredom proneness are more likely to perceive the environment as monotonous and constrained; thus, they would have a strong desire for sensation seeking, such as substances use [25], alcohol abuse [26], rule breaking [27], social network addiction [28], and problematic smartphone use [29]. Boredom proneness is a prominent risk factor for deviant behaviors. A study has confirmed that boredom proneness and online deviant behaviors are significantly correlated [30].

Recently, rumination—one’s tendency to think repetitively, uncontrollably, and intrusively about the possible causes and consequences of stressors [31]—has received growing attention as a risk factor for deviant behavior. It is regarded as a highly dysfunctional cognitive strategy for coping with stressful events [32]. Research has shown that rumination positively correlates with offline passive consequences (such as depression ^[33][34][33,34], aggression [35], suicide [36], and so on), and online negative outcomes (such as problematic mobile phone use [37], online trolling [38], and so on). Resource depletion theory argues that rumination leads to individuals’ limited cognitive resources being occupied too much and results in damaged executive control function and failure of self-control [39]; thus, individuals with rumination are prone to engage in deviant behaviors. Consequently, reswearchers deem that rumination is positively associated with online deviant behaviors.

According to the stress-reactive model of rumination, individuals who experience a stressful event or negative emotion would experience rumination [32]. As a common negative emotion, boredom positively correlates with rumination ^[40][41][42][40,41,42]. Similarly, elaborated control theory may explain this relationship; that is, rumination occurs when people recognize discrepancies between desired goals and current states [43]. In addition, boredom reflects a discrepancy between the current, meaningless situation and a desired, more meaningful situation [44]. However, these studies mainly focused on boredom in certain situations (for example, workplace, school, during the COVID-19 lockdown, etc.). Whether one feels boredom may partly depend on boredom proneness and it is possible that individuals with high boredom proneness struggle with more feelings of boredom. Based on this reasoning, rwesearchers deem that boredom proneness correlates with rumination.

Taken together, rwesearchers put forward the hypothesis that rumination plays a mediating role between boredom proneness and online deviant behaviors.

Gender differences in online deviant behaviors have been examined in previous studies. Males are more likely to engage in online deviant behaviors than females ^[5][18][5,18], particularly in certain forms of online deviant behaviors (such as deviant cyber-sexual activities [45] and cyberbullying [46]). Hence, researchwers consider gender differences here and deem that gender may act as a moderator between boredom proneness and online deviant behaviors. There are two reasons for this: First, according to the general strain theory, male with strains are more conducive to violence, while females are more prone to the escapist form of crime [47]. Being engaged in boredom is regarded as a strain; thus, males with high boredom proneness engage in more online deviant behaviors than females. Second, sensation-seeking theory confirms that someone with a high level of boredom proneness tends to engage in high sensation-seeking activities to avoid or reduce boredom and empirical studies have shown that males prefer exciting and risky behaviors compared to females, such as online deviant behaviors.

Furthermore, the stress-reactive model of rumination states that rumination can exaggerate the influence of extreme information on cognition, which makes it difficult for individuals to disengage from negative information [31]. Hence, rumination may aggravate the relationship between boredom and online deviant behaviors. Owing to gender differences in online deviant behaviors, reswearchers deem that gender also plays a moderating role between rumination and online deviant behaviors. That is, for males, rumination results in more online deviant behaviors than females.