Humor is linked with wisdom: a wise person knows how to use humor or when to laugh at oneself

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Understanding and creating humor require a sequence of mental operations. Cognitive psychologists favor a three-stage theory of humor. To be in on the joke you need to be able to:

  1. Mentally represent the set up of the joke.
  2. Detect an incongruity in its multiple interpretations.
  3. Resolve the incongruity by inhibiting the literal, nonfunny interpretations and appreciating the meaning of the funny one.

An individual’s knowledge is organized in mental memory structures called schemas. When we see or think of something, it activates the relevant schema; Our body of knowledge on that particular topic immediately comes to mind.

For example, when we see cows in a Far Side cartoon, we activate our bovine schema (stage 1). But when we notice the cows are inside the car while human beings are in the pasture grazing, there are now two mental representations in our conscious mind: what our preexisting schema mentally represented about cows and what we imagined from the cartoon (stage 2). By inhibiting the real-world representation (stage 3), we find the idea of cows driving through a countryside of grazing people funny. “I know about cows” becomes “wait, cows should be the ones in the field, not people” becomes an appreciation of the humor in an implausible situation.

Funny is the subjective experience that comes from the resolution of at least two incongruous schemas. In verbal jokes, the second schema is often activated at the end, in a punchline.

That’s not funny

There are at least two reasons that we sometimes don’t get the joke. First, the punchline must create a different mental representation that conflicts with the one set up by the joke; timing and laugh tracks help signal the listener that a different representation of the punchline is possible. Second, you must be able to inhibit the initial mental representation.

When jokes perpetuate a stereotype that we find offensive (as in ethnic, racist or sexist jokes), we may refuse to inhibit the offensive representation. Violence in cartoons is another example; In Roadrunner cartoons, when an anvil hits the coyote, animal lovers may be unable to inhibit the animal cruelty meaning instead of focusing on the funny meaning of yet another inevitable failure.

This incongruity model can explain why older adults do not comprehend jokes as frequently as younger adults. Due to declines tied to the aging process, older adults may not have the cognitive resources needed to create multiple representations, to simultaneously hold multiple ones in order to detect the incongruity, or to inhibit the first one that was activated. Getting the joke relies on working memory capacity and control functions. However, when older adults succeed in their efforts to do these things, they typically show greater appreciation of the joke than younger adults do and report greater life satisfaction than those who don’t see the humor.

There may be other aspects to humor, though, where older adults hold the advantage. 

Wisdom is a form of reasoning that increases with age and is correlated with subjective well-beingHumor is linked with wisdom – a wise person knows how to use humor or when to laugh at oneself.

Additionally, intuition is a form of decision-making that may develop with the expertise and experience that come with aging. Like humor, intuition is enjoying a bit of a renaissance within psychology research now that it’s been reframed as a major form of reasoningIntuition aids humor in schema formation and incongruity resolution, and we perceive and appreciate humor more through speedy first impressions rather than logical analysis.

Traveling through time

It’s a uniquely human ability to parse time, to reflect on our past, present and future, and to imagine details in these mental representations. As with humor, time perspective is fundamental to human experience. Our ability to enjoy humor is enmeshed with this mental capacity for time travel and subjective well-being.

People vary greatly in the ability to detail their mental representations of the past, present and future. For example, some people may have what psychologists call a negative past perspective – frequently thinking about bygone mistakes that don’t have anything to do with the present environment, even reliving them in vivid detail despite the present or future being positive.

Time perspective is related to feelings of well-being. People report a greater sense of well-being depending on the quality of the details of their past or present recollections. When study participants focused on “how” details, which tend to elicit vivid details, they were more satisfied with life than when they focused on “why,” which tend to elicit abstract ideas. For example, when remembering a failed relationship, those focusing on events that led to the breakup were more satisfied than those dwelling on abstract causal explanations concerning love and intimacy.

One study found that people who use humor in positive ways held positive past time perspectives, and those using self-defeating humor held negative past time perspectives. This kind of study contributes to our understanding of how we think about and interpret social interactions. Such research also suggests that attempts to use humor in a positive way may improve the emotional tone of details in our thoughts and thereby our moods. Clinical psychologists are using humor as a treatment to increase subjective well-being.

In ongoing recent work, my students and I analyzed college students’ scores on a few common scales that psychologists use to assess humor, time perspective and the need for humor – a measure of how an individual produces or seeks humor in their daily lives. Our preliminary results suggest those high in humor character strength tend to concentrate on the positive aspects of their past, present and future. Those who seek humor in their lives appear in our study sample also to focus on the pleasant aspects of their current lives.

Though our investigation is still in the early phase, our data support a connection between the cognitive processes needed to mentally time-travel and to appreciate humor. Further research on time perspectives may help explain individual differences in detecting and resolving incongruities that result in funny feelings.

Learning to respect laughter

Experimental psychologists are rewriting the book on humor as we learn its value in our daily lives and its relationship to other important mental processes and character strengths. As the joke goes, how many psychologists does it take to change a light bulb? Just one, but it has to want to change.

Studying humor allows us to investigate theoretical processes involved in memory, reasoning, time perspective, wisdom, intuition and subjective well-being. And it’s a behavior of interest in and of itself as we work to describe, explain, control and predict humor across age, genders and cultures.

Whereas we may not agree on what’s funny and what isn’t, there’s more consensus than ever among experimental psychologists that humor is serious and relevant to the science of behavior. And that’s no laughing matter.


Humor is a universal phenomenon but is also culturally tinted. In this article, we reviewed the existing research that investigates how culture impacts individuals’ humor perception and usage as well as humor’s implications for psychological well-being. Previous research has substantiated evidence that Easterners do not hold as positive an attitude toward humor as their Western counterparts do.

This perception makes Easterners less likely to use humor as a coping strategy in comparison with Westerners. Despite this difference, Westerners and Easterners have similar patterns in the relationship between their humor and psychological well-being index, though the strength of the relationship varies across cultures. Implications and potential future research avenues discussed.

Cultural Differences in Humor Perception, Usage, and Implications

Humor refers to the tendency to experience or express what is amusing and funny, which is always accompanied with emotional response and vocal-behavioral expressions, such as laughter and smiling (Chen and Martin, 2007; Martin and Ford, 2018). Generally, humor is present in all human cultures (Fry, 1994). However, people from different cultural backgrounds may see humor in different ways. As it is remarked by Martin and Ford (2018):

Humor is a universal human activity that most people experience many times over the course of a typical day and in all sorts of social contexts. At the same time, there are obviously important cultural influences on the way humor is used and the situations that are considered appropriate for laughter (p. 30).

Humor is universal but also culturally specific. Previous literature has shown that Easterners and Westerners differ in humor perception (e.g., Chen and Martin, 2005, 2007), however, the results about East-West cultural difference in humor usage, the relationship between humor and psychological well-being are rather mixed and inconsistent (e.g., Kazarian and Martin, 2004; Chen and Martin, 2007; Hiranandani and Yue, 2014).

Whether there is East-West cultural difference in humor perception, usage, as well as humor and psychological well-being relationship remains unclear. Understanding how culture influences humor perception, humor usage, as well as humor’s implications for psychological well-being is of great importance because humor has significant consequences for human psychological well-being (e.g., Martin, 2001; Chen and Martin, 2007; Martin and Ford, 2018).

To clarify this question, we need to have a systematic view about cultural differences in humor. The aim of this article provides a review of how culture influences humor perception and usage as well as the relationship between humor and psychological well-being so as to shed light on the issue of using humor to promote individuals’ psychological well-being. Lastly, we also suggest some revenues for future research.

Cultural Differences in Humor Perception

Since the era of Ancient Greece, it has been a long tradition among Westerners to embrace humor (Grant, 1924/1970; Martin and Ford, 2018). Westerners have associated humor with positivity and seen humor as natural amusement expressions (Apte, 1985). In the late nineteenth century, Freud (1928) regarded humor as a defense mechanism against obstacles and distress.

In the perspective of Psychoanalysis, humor was regarded not only as a way to help people release fear and anxiety, but it also provides an amusing, funny, and less scaring perspective toward people’s inner fear (Martin and Ford, 2018). In the twentieth century, psychologists in Western world began to talk about the positive effects of humor.

For example, humor is regarded as a desirable positive trait of an individual (Allport, 1937; Maslow, 1968; Mintz, 1983; Mindess et al., 1985). Humorous people are thought to be more attractive (e.g., Regan and Joshi, 2003; Fraley and Aron, 2004) and more motivating, creative, and capable (e.g., Sternberg, 1985; Priest and Swain, 2002). Humor also takes on meaning as an essential element of psychological health associated with self-awareness, well-adjustment, and affability (Allport, 1961; Martin and Ford, 2018).

In sharp contrast, Easterners’ attitudes toward humor are not that positive. Specifically, in China, Confucianism has devalued humor. Chinese self-actualization denigrates humor while stressing restriction and seriousness (Bond, 1996; Liao, 1998, 2007; Yue, 2010). Chinese are reluctant to admit they are humorous out of fear of jeopardizing their social status. Chinese do not think that humor is a desirable personality trait (Rudowicz and Yue, 2002; Yue, 2011).

The views toward humor are reflected in behaviors. Surveys and empirical research provide evidence for the cultural differences in humor perception. For example, Chinese do not see humor as an essential element of creativity (e.g., Rudowicz and Yue, 2011; Yue and Hui, 2011, 2015) like Westerners do (e.g., Murdock and Ganim, 1993; Kellner and Benedek, 2017; Lu et al., 2019). Yue X. et al. (2016) found that Canadians rated humor more importantly than their Chinese counterparts.

They also provided evidence for the assumption that Easterners do not associate humor with positivity as Westerners do by finding that Hong Kong participants who were primed with Western culture would like to use more positive words to depict a humorous person than participants who were primed with Chinese cultural icons. Moreover, Chen and Martin (2005) found that Chinese students rated themselves as being less humorous than Canadian students. Yue X. et al. (2016) also found similar results.

East Asians, including mainland Chinese, Taiwanese, and Hong Kong people, were consistently found to report lower self-rated humor than Westerners (e.g., Liao, 2001; Chen and Martin, 2005, 2007; Liao and Chang, 2006). This research provides direct evidence that Westerners associate humor with positivity, which is not the case for Chinese.

However, Chinese culture is not purely dominated by Confucianism. Other philosophies also impact Chinese attitudes toward humor (Yue, 2010, 2011). One of these philosophies is Taoism. Different from Confucianism’s despising on humor, Taoism regards humor as “an attempt of having witty, peaceful and harmonious interaction with nature” (Yue, 2011, line 4, p. 464).

The tug between different philosophies makes the appreciation–despising complex toward humor deeply rooted in Chinese culture, which makes Chinese have quite an ambivalent attitude toward humor (Yue, 2010, 2011). Yue (2011) summarized three ambivalent attitudes toward humor among Chinese.

The first is valuing humor but considering themselves to lack the trait of humor. The second is how being humorous is not associated with being an orthodox Chinese. The third is that humor is not important for everyone but exclusively for those with expertise. He also conducted survey research to test his assumptions, which showed that even though Chinese thought that humor was important in daily life, they would not say that they were humorous themselves. When asked to choose personality attributes, the top 10 important personality attributes that Chinese chose for humor were fundamentally different from those they chose for the Chinese personality.

Chinese were likely to nominate a person with humorous expertise rather than an ordinary person as being a humorous person (Yue, 2011). Other research evidence supports this assumption as well. As Yue X. et al. (2016) found in the humor nomination study, Chinese prefer to name experts rather than their friends or relatives as humorous people, whereas the opposite was true for Canadians.

Similar results were also found by Yue et al. (2010b) and Yue and Hiranandani (2014). Moreover, using the Implicit Association Test (IAT), Jiang et al. (2011) found that despite Chinese students not showing significant differences in explicit attitudes toward humor in comparison with American students, they were more likely to associate humor implicitly with negative adjectives.

In summary, Westerners and Easterners’ views toward humor fundamentally differ from each other. Westerners regard humor as a desirable trait of an ideal self, associate humor with positivity, and stress the importance of humor in their daily life. On the contrary, Easterners’ attitudes toward humor are not that positive. Specifically, the apprehension–despising complex makes Chinese have ambivalent attitudes toward humor. Even though Chinese might sometimes admit that humor is important in daily life, they do not think they are humorous themselves. For Chinese, humor is a talent that exclusively belongs to experts and is not a desirable trait of their ideal personality.

Cultural Difference in Humor Usage

Cultural difference in humor perception directly influences humor usage. In Western culture, humor has become an indispensable coping strategy for Westerners (Moran and Massam, 1999; Lefcourt, 2001). According to psychoanalysis theory, humor acts as a defense mechanism to help people fight against negative events (Freud, 1928; Shurcliff, 1968).

On the one hand, humor serves as a catharsis for negative energy (Freud, 1960/1905). On the other hand, humor allows people to perceive the anger and fear arising from incongruity in different ways (Martin and Ford, 2018). However, the appreciation–despising complex makes things different in Chinese culture. As we discussed above, Westerners tend to regard humor as a common positive trait, whereas Chinese tend to see humor as a special talent that is not commonly seen in ordinary people.

Thus, it is unsurprising that Westerners tend to use humor more frequently than Chinese (e.g., Liao, 2001; Chen and Martin, 2005, 2007; Liao and Chang, 2006; Yue, 2011). Research has found a West-East cultural difference in humor usage. For example, humor is not an important coping device in Japan as it is in the United States (Abe, 1994).

Chinese students were less likely to use humor as a coping strategy with stress than their Canadian counterparts (e.g., Chen and Martin, 2005, 2007). Similarly, Singaporean students were less likely to use humor to cope with difficulty than American students (Nevo et al., 2001). As suggested by Yue X. et al. (2016), in Western countries, no matter who they are, people have a general tendency to use humor in coping with stress or difficulties, which is not true in Eastern countries.

To be specific regarding cultural differences in humor usage, we turn to the four types of humor: self-enhancing, affiliative, self-defeating, and aggressive humor (Martin et al., 2003). The four types of humor have been found to be applicable in different countries, such as Canada, China, the United States, Lebanon, and Belgium (Saroglou and Scariot, 2002; Martin et al., 2003; Chen and Martin, 2007; Taher et al., 2008). However, people from different cultural backgrounds may use them in different ways.

Research on usage differences in the four types of humor across countries or regions indicates that Easterners tend to use more adaptive humor, while Westerners tend to use more maladaptive humor. For example, Hiranandani and Yue (2014) found that students from India and Hong Kong, both having cultures prizing collectivism, used more affiliative and self-enhancing humor than aggressive and self-defeating humor.

Similarly, Hong Kong students reported more use of aggressive and self-defeating humor and less use of affiliative and self-enhancing humor than mainland Chinese students (e.g., Yue et al., 2010a, 2014b; Yue X. D. et al., 2016). This could be explained by the fact that the bicultural background of Hong Kong makes Confucianism and collectivism less influential there than in mainland China.

In addition, Chen and Martin (2007) asked Chinese and Canadian students to complete the Humor Styles Questionnaire (HSQ) and Coping Humor Scale (CHS). They found that Canadian students reported using the four types of humor more than their Chinese counterparts did, especially aggressive humor.

No significant relationship was found between aggressive humor and coping in Chinese students, indicating that Chinese are less likely to use aggressive humor as a coping strategy. This difference is unsurprising. Aggressive humor is associated with high individualism, which emphasizes independence and assertiveness, and low collectivism, which de-emphasizes interdependence and harmony (Kazarian and Martin, 2006; Martin and Ford, 2018). Even as children, Chinese tend to see humor as a sign of aggression and as disruptive to social relationships, whereas Canadians tend to see humor as a socially desirable leadership trait (Chen et al., 1992).

Additionally, Kalliny et al. (2006) found differences in Arab and American humor usage, specifically that Americans used significantly more self-defeating and self-enhancing humor, while there were no differences in the use of affiliative and aggressive humor. They suggested that the greater use of self-defeating humor in American culture may be due to the desire to equalize and lower power distances present in American culture, while greater use of self-enhancing humor may be attributed to the fact that self-enhancing humor helps them gain focus and attention (Kalliny et al., 2006).

These studies were conducted to examine cultural differences in humor usage across countries without taking specific cultural variables into consideration. Thus, it is still not quite clear whether individual or cultural differences account for the differences in humor usage.

Kazarian and Martin (2004) systematically investigated the relationships between culture and the four types of humor usage in terms of specific cultural dimensions. Comparing Lebanese, Canadians,’ and Belgians’ humor usage, they found that individuals from horizontal collectivist cultures that emphasize harmony and group cohesion are more likely to use affiliative humor, whereas individuals from a vertical collectivist culture that values self-sacrifice for the sake of group are more likely to employ self-defeating humor.

Furthermore, individuals from vertical individualist cultures that embrace competitiveness are more likely to use aggressive humor to enhance their hierarchical status. It was also found that affiliative humor was used to the same degree among the various cultural orientations (Kazarian and Martin, 2004). This research helps to clarify how culture impacts humor usage. However, a survey only provides correlational evidence; more refinement is needed.

Moreover, specific humor types may have different connotations across cultures, which would influence humor usage in different cultural backgrounds. For example, Chen and Martin (2007) found that Chinese considered the item “If I am having problems or feeling unhappy, I often cover it up by joking around, so that even my closest friends don’t know how I really feel” to be more like self-enhancing humor than self-defeating humor, like Canadians did.

This indicates that using humor to conceal one’s problems is more of a self-enhancing than a self-defeating strategy for Chinese (Chen and Martin, 2007). This may also be attributed to the fact that saving face is one of the most important attributes for the Chinese personality (e.g., Gao, 1998; Yue, 2011). Thus, one would expect people to use humor according to its culturally tinted connotations and thus use humor differently.

In summary, generally, we could say that Easterners are less likely to use humor as a coping strategy in comparison with their Western counterparts because of the East-West cultural difference in humor perception. When it comes to the specific humor types, it seems that Easterners tend to use less aggressive but more affiliative humor than Westerners. However, the result is highly contingent on the specific cultural dimensions valued in different cultural backgrounds.

It is true when collectivism that stresses harmony and interdependence dominates in Eastern culture. The cultural difference in specific humor usage has yet been conclusive due to a lack of consideration of specific cultural variables. Furthermore, some humor coping strategies may have different connotations under different cultural backgrounds, which would directly impact how humor is used in different cultural backgrounds.

Relationship Between Cultural Differences in Humor and Psychological Well-Being

Humor has implications for both physical and psychological well-being. Martin (2001) proposed four theoretical mechanisms underlying humor’s effect on health: positive changes in the physiological system brought by laughter, positive emotions accompanying humor, the stress-moderating effect of humor, and the social support associated with humor’s social facilitation function. Martin and Ford (2018) further suggested that the buffering effect of humor comes from cognitive reframing and emotional management.

In fact, psychologists have accumulated evidence for the positive effects of humor: humor improves immunity, facilitates creativity, saves face, relieves stress and tension, creates a more positive self-concept, improves relationships with others, lowers stress, and increases positive emotions and life satisfaction (e.g., Kuiper and Martin, 1993; Martin et al., 1993; Kuiper and Olinger, 1998; Parrish and Quinn, 1999; Lefcourt, 2001; Martin, 2001, 2002; Abel, 2002; Yue et al., 2010a; Cheung and Yue, 2012; Martin and Ford, 2018).

Not all forms of humor are beneficial. As discussed earlier, affiliative, aggressive, self-enhancing, and self-defeating humors are four humor types that seem to exist in both Western and Eastern cultures (Martin et al., 2003; Chen and Martin, 2007). Research on Western cultural background has suggested that affiliative and self-enhancing humors are adaptive, whereas aggressive and self-defeating humor are maladaptive (e.g., Martin et al., 2003; Kuiper et al., 2004).

Research has shown that affiliative humor can promote adjustment; relieve anxiety, depression, and attachment avoidance; and increase subjective well-being, individuals’ sense of identity and belongingness (e.g., Chen and Martin, 2007; Cann et al., 2008; Frewen et al., 2008).

Self-enhancing humor can help one cope with stress and misfortunes in life; it is positively associated with optimism and self-esteem and negatively associated with depression (Thorson et al., 1997; Chen and Martin, 2007; Dozois et al., 2009; Martin and Ford, 2018).

Aggression humor is maladaptive in terms of bringing mental health benefits, as it may deter adjustment and resilience and cause attachment avoidance, lower self-esteem, loneliness, aggression, and maladjustment in the family (e.g., Martin et al., 2003; Kuiper et al., 2004; Kazarian and Martin, 2006; Cann et al., 2008). Self-defeating humor is also detrimental to adjustment, as it may trigger depression or anxiety (e.g., Martin et al., 2003; Chen and Martin, 2007; Cann et al., 2008; Martin and Ford; 2018).

Despite Easterners generally being less likely to use humor as a coping strategy in comparison with their Western counterparts, Easterners also benefit from humor. For example, affiliative and self-enhancing humor could help sojourning mainland Chinese students studying in Hong Kong cope with acculturative stress, increase their level of life satisfaction, and decrease their depressive mood (Cheung and Yue, 2012).

It is positively associated with higher levels of self-compassion for Hong Kong students (Yue et al., 2017), higher levels of optimism, and lower levels of loneliness and distress (Sun et al., 2009; Yue et al., 2010a, 2014b; Cheung and Yue, 2013), for both mainland Chinese and Hong Kong students, and is positively associated with self-esteem for mainland Chinese, Hong Kong, and Indian students (Yue and Hiranandani, 2014; Yue et al., 2014a).

Maladaptive humor also seems to be detrimental to Easterners’ psychological well-being, although the results are not that consistent. Consistent with Westerners, self-defeating humor is positively correlated with loneliness and self-esteem for Chinese (Sun et al., 2009; Yue et al., 2014b). Cheung and Yue (2013) found that aggressive and self-defeating humor were positively associated with depression, anxiety, and irritation for Chinese students from Guangzhou, Hong Kong, and Macau.

However, when investigating how the four types of humor impact mainland Chinese’s adjustment when studying in Hong Kong, Cheung and Yue (2012) found that aggressive and self-defeating humor did not consistently affect mainland Chinese adjustment. Additionally, Hiranandani and Yue (2014) found that aggressive humor was not significantly associated with self-esteem for Indian or Chinese students. Using Hong Kong students as their sample, Yue et al. (2014a) found that aggressive humor was not significantly associated with self-esteem or subjective well-being.

These inconsistent results may be due to the Chinese dialectic thinking style, which is characterized by contradiction (Peng and Nisbett, 1999; Hou and Zhu, 2002; Ji et al., 2010). Take the inconsistent results of aggressive humor, for instance. On the one hand, Chinese culture emphasizes interdependence and harmony (Hwang, 1987; Cheung et al., 2001), which makes Chinese less likely to use aggressive humor in their daily life (Chen and Martin, 2007; Yue, 2010, 2011).

On the other hand, aggressive humor can still buffer harm (Martin and Ford, 2018). The contradictory characteristic of the Chinese thinking style makes Chinese behave in different manners from how they think, thus further blurring the relationship between maladaptive humor and psychological well-being. Alternatively, this may be because the direct translation of the English Humor Style Questionnaire (HSQ) could not fully capture maladaptive humor types in China.

Some research has examined the cultural differences in humor implications systematically. Investigating Chinese and Canadian samples simultaneously, Chen and Martin (2007) did not find cultural differences in the relationship between humor and psychological well-being. A similar correlational pattern was found in both Chinese and Canadian samples.

They found that for both Chinese and Canadian students, mental health was positively associated with affiliative and self-enhancing humor but negatively associated with aggressive and self-defeating humor. Furthermore, Cheung and Yue (2012) found that for mainland Chinese students who study in Hong Kong, affiliative humor appeared to buffer all four kinds of hassles linked with depression, whereas self-enhancing humor only buffered the study hassles linked with depression.

This indicates that self-enhancement humor is not that potent in helping mainland Chinese to cope with acculturative stress. This may be attributed to Chinese not adopting the Western way of self-enhancement (Sedikides et al., 2003). Yue et al. (2010a) reported that adaptive humor types (affiliative and self-enhancing humor) were positively and maladaptive humor types (aggressive and self-defeating humor) were negatively associated with optimism, for both mainland Chinese and Hong Kong students.

The correlation was stronger for mainland Chinese than for the Hong Kong students. Yue et al. (2014b) found that self-defeating humor explained social and emotional loneliness for Hong Kong students but only social loneliness for mainland China students. These results may be because that mainland Chinese students use more affiliative and self-enhancing but less aggressive and self-defeating humor than Hong Kong students (e.g., Yue et al., 2010a, 2014b), as a consequence of the weaker influences of collectivism and Confucianism in Hong Kong society (Yue et al., 2010a).

In sum, Westerners and Easterners do differ in the relationship between humor and psychological well-being, not qualitatively but quantitatively. Although Chinese students tend to appreciate and use humor less than Western students do, Chinese are still more likely to embrace adaptive humor styles, which have the greatest influence on their mental health, while maladaptive humor styles are less influential.

reference link : https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6361813/


Source: The Conversation

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