Many studies converge on the value of studying contact as a predictor of connectedness, demonstrating that contact (e.g., Kals et al., 1999; Mayer and Frantz, 2004, S1; Schultz and Tabanico, 2007, S3–5; Nisbet et al., 2009; Beery, 2013; Tam, 2013; Braun and Dierkes, 2017; Lumber et al., 2017), in a variety of forms, improves connectedness—whether it be contact with nature through nature-based tourism (Burbach et al., 2012; Wheaton et al., 2016) wilderness expeditions (Barton et al., 2016; Richardson et al., 2016), or contact via walking in nature (Mayer et al., 2009; Nisbet and Zelenski, 2011; Nisbet et al., 2019). In addition to contact with relatively organic forms of nature, contact with contrived nature, such as zoos, can foster a sense of connectedness (e.g., Schultz and Tabanico, 2007; Bruni et al., 2008). There is also substantial evidence that living closer to nature (e.g., Cheng and Monroe, 2012), living in a rural environment (e.g., Hinds and Sparks, 2009; Harvey et al., 2016) and more frequent exposure to nature (e.g., Kals et al.,1999; Mayer and Frantz, 2004, S1; Schultz and Tabanico, 2007, S5; Hinds and Sparks, 2009; Nisbet et al., 2009; Scott, 2010, S1–2; Tam, 2013, S2; Pensini et al., 2016; Richardson et al., 2016; Swami et al., 2016; Larson et al., 2018; Rosa et al., 2018) are associated with higher levels of connectedness. Contact with nature can even be as subtle as exposure to plants in a lab space (Weinstein et al., 2009). There is also some evidence to suggest that literal contact with nature may facilitate connectedness: one study found that comfort level walking barefoot is associated with increased connectedness; however, the causal direction of this relationship remains subject to interpretation and in need of further research (Harvey et al., 2016). Ultimately, many studies investigating the effect of contact with actual nature on connectedness conclude that it has a positive effect.

Contact with nature, both as child (e.g., Tam, 2013) and as an adult, is perhaps the most well documented antecedent of connectedness; research has consistently shown that spending time around or in nature (e.g., Mayer et al., 2009), viewing nature (e.g., videos; Richardson and Sheffield, 2015), or otherwise experiencing nature (e.g., VR; Ahn et al., 2016) can foster a sense of connectedness. Despite this consistency, there are several areas for advancement.

As noted above, while much research has been dedicated to understanding if contact with nature can increase connectedness, little, if any, research has adequately addressed the question of when and why contact with nature might not increase connectedness—cases where contact with nature may simply not have an effect, cases where some feature of the experience inhibits the normally positive effect, or, most importantly, cases where something about the situation actively diminishes connectedness. There are several studies in which contact with nature did not seem to affect connectedness (e.g., Lumber et al., 2017). Yet, we do not have a framework to understand why some studies find these null effects of contact with nature (e.g., Lengieza and Swim, 2021) in order to determine which null effects are theoretically meaningful and which are most likely methodological flukes. For example, one study investigated whether nature sounds would increase connectedness but found no evidence to support this notion (Spendrup et al., 2016). It might be easy to explain these findings by assuming that the manipulation may not have been sufficiently salient to be effective. However, to illustrate, these findings might have important theoretical implications; it may be that at a certain point, some contact is superficial or insufficiently meaningful to alter our mental landscape or, perhaps more importantly for theory, it may potentially be that nature sounds are not an important part of the effect of contact on connectedness. Ultimately, more attention should be paid to understanding when contact does not increase connectedness to disentangle methodological limitations from theoretically meaningful boundary conditions.

Moreover, we do not have a framework to predict when contact with nature should be expected to diminish connectedness. That is, there is virtually no research about conditions when contact with nature results in decreased connectedness. For example, contact with the “bugs and mud” of nature might create an aversive experience that counteracts the usually positive effect of nature, perhaps because such exposure feels threatening (see research on negative affect in later sections). The two studies appearing in this review closest to answering such questions investigated the how connectedness is affected by exposure to natural disasters—by all accounts a less than positive encounter with nature (e.g., Walters et al., 2014; Brown, 2017). While the results paint opposing pictures—in one study exposure to natural disasters was associated with increased connectedness (Walters et al., 2014) and in the other the opposite was true (Brown, 2017)—the research questions themselves are emblematic of an interest in the negative side of contact with nature. Notably, this interest in the potential negative side of contact with nature in terms of its effect on connectedness is similar to research on biophobia (Zhang et al., 2014a); however, research specifically focusing on the extent to which contact with aversive elements of nature promotes or undermines including nature in our sense of self or feeling a sense of oneness with nature is still needed.

Both a framework for explaining null effects and predictions about when contact with nature might have a negative effect are important for the development of theories describing the formation of connectedness. Future research can provide answers to these types of questions, and, subsequently, a better theoretical understanding of the different forms of contact with nature. However, it will require a shift from primarily looking for whether contact with nature promotes connectedness to explicitly examining instances in which contact with nature either does not promote connectedness or actively diminishes it as well as a focus on developing theories to explain null and/or negative effects.

Additionally, this section highlights that there are unanswered questions concerning comparisons between types of contact with nature. The presence of research showing that features of the environment matter when it comes to connectedness (e.g., Duffy and Verges, 2010; Wyles et al., 2019) indicates that contact with nature is likely a heterogenous category which may contribute to variability in the degree to which contact with different types of nature will affect connectedness (c.f., Duffy and Verges, 2010). If fostering connectedness is a goal, it is important to understand what features of the environment influence the degree to which contact with nature influences connectedness. Though the effects of actual first-hand contact with nature have received considerable attention more research is needed to know whether certain types of contact with actual nature have differential effects on connectedness—for example, blue spaces vs. rural green spaces or urban green spaces (c.f., Wyles et al., 2019). We also see few studies comparing videos of nature to actual nature (c.f., Mayer et al., 2009, S2–3) and none comparing VR and actual nature.

Last, despite research on contact with nature focusing on both adults and children, we do not know during which period of life contact with nature is most important. Although current evidence, noted above, suggests that adult contact is more important than childhood contact (e.g., Rosa et al., 2018), asking which type of contact—child or adult—begs the question of whether the distinction is meaningful.

In sum, research investigating the effects of contact with nature on connectedness should take the next steps and begin to explore (1) the heterogeneity of contact with nature (2) across the lifespan as well as begin focusing on (3) when—and subsequently why—contact with nature fails to promote, or actively suppresses, connectedness.

Activities that involve some degree of contact with nature—such as gardening (e.g., Beery, 2013; Sanguinetti, 2014), planting trees (e.g., Whitburn et al., 2019), walking dogs (Beery, 2013; Wyles et al., 2019), having picnics in nature, studying plants and animals (Beery, 2013) depicting nature artistically (Bruni et al., 2017), or receiving interpretation while touring nature parks (Burbach et al., 2012)—are positively associated with connectedness. For many of these activities it is unclear if the relations exist merely because these activities bring the individual into contact with nature. The alternative possibility is that the activities in some way enhance, or work independent of, the incidental contact with nature. Unfortunately, the extant literature does little to help dissociate these possibilities. One study, however, suggests that noticing nature increases connectedness and this effect seems to be above and beyond contact with nature; even though all participants spent equal time in nature, compared to business as usual, participants instructed to notice nature experienced increased connectedness (Passmore and Holder, 2017). This study, as an example, highlights the possibility that activities that involve contact with nature might be more than just contact with nature.

Just as not all contact with nature enhances connectedness, not all activities that involve contact with nature increase connectedness. Indeed, some activities, such as going to the beach and playing on a playground were not correlated with connectedness (Bruni and Schultz, 2010, S3) and other activities such as waterskiing and wake boarding (Beery, 2013), as well as exercising or playing in nature (Wyles et al., 2019) have been reported to be negatively correlated with connectedness. One possibility is that these activities involve treating nature as merely an arena in which to engage in the activity which could potentially result in nature becoming a non-salient background element of the experience or may even result in viewing nature from an entirely different perspective, where nature is objectified as a means to an end. Regardless, that these activities—which involve contact with nature—still seem to decrease connectedness suggests that activities can have an effect that is independent of the effect of contact with nature.

Environmental education is one commonly studied activity appearing in the connectedness literature. The majority of evidence appearing in this review suggests that participation in environmental education programs—which does not necessarily entail direct physical contact with nature (e.g., Lankenau, 2018)—is associated with increases in connectedness (Mayer and Frantz, 2004; Clayton et al., 2011; Liefländer et al., 2013; Sellmann and Bogner, 2013; Johnson-Pynn et al., 2014; Braun and Dierkes, 2017; Crawford et al., 2017; Otto and Pensini, 2017; Cho and Lee, 2018; Lankenau, 2018; Dopko et al., 2019). However, as with contact with nature, there are exceptions, with some studies showing no effect of participation in environmental education (e.g., Ernst and Theimer, 2011). And, again, as with contact with nature, the reasons for these disparities are not well outlined in the literature. We do not know what kinds of programs—classroom vs. field, broad verses specific, etc.—are most likely to increase connectedness. There is some evidence, however, that longer programs are more effective at fostering connectedness (e.g., Johnson-Pynn et al., 2014; Braun and Dierkes, 2017). This effect may be attributable to several things such as more impactful content, more immersion, or some other element that differs between longer and shorter programs, but the exact reason for this effect requires further research.

There are also other activities which can promote connectedness that have both the potential to influence how we think about nature and do not necessarily involve actual contact with nature.

There is evidence that a variety of activities enhance connectedness. This includes activities such as gardening or planting trees (e.g., Whitburn et al., 2019), participating in environmental education (e.g., Lankenau, 2018), as well as meditating (e.g., Aspy and Proeve, 2017) and certain recreational drug use (Forstmann and Sagioglou, 2017).

In addition to replicating findings and experimentally confirming correlational relationships, future research should address the question, already noted in this section, of whether the activities that involve contact with nature reviewed in this section have an effect above and beyond the effect of having contact with nature and if so, why. While some of these activities can involve varying degrees of contact with nature, it seems unlikely that they can be boiled down to simply be about being in nature. Instead, it is likely that they enhance the contact with nature that happens to be involved in that activity. For example, gardening (c.f., Beery, 2013) also includes a component of taking care of or nurturing nature. Does this additional facet of caring for nature bring something new to the table or can it really be reduced to being in contact with nature? The need to understand whether nature-based activities have affects above and beyond contact with nature is also particularly apparent for activities that seem to suppress connectedness despite involving contact with nature such as exercising or playing in nature (Wyles et al., 2019) or waterskiing and wake boarding (Beery, 2013). Research is needed to understand why these activities overshadow the effects of contact with nature.

Finally, there may be moderators of the relationship between various activities or experiences and connectedness. For example, age may moderate the effect of regular participation in outdoor activities and connectedness; regular participation—vs. non-regular participation—may only matter for older age groups (Beery, 2013). As illustrated in the next section, age is only one of many individual differences that may be worthy of consideration. Few studies, though, have investigated the possibility of factors that moderate the relationship between connectedness and the experiences and activities listed above. Therefore, research on the effect of various activities on connectedness should pay attention to potential moderators.

Research on age suggests that our sense of connectedness might be influenced by where we are in our lifespan. Several studies with adults indicate that age is positively associated with connectedness (Burbach et al., 2012; Beery, 2013; Sanguinetti, 2014; Zhang et al., 2014b, S1–2; Harvey et al., 2016; Lumber et al., 2017; Nour et al., 2017; Diessner et al., 2018). However, a sizeable number of studies with adults suggest no relationship (Mayer and Frantz, 2004; Dutcher et al., 2007; Bruni et al., 2008; Weinstein et al., 2009, S1–3; Walters et al., 2014; Unsworth et al., 2016, S1–2; Swami et al., 2016; Brown, 2017; Whitburn et al., 2019). In contrast, studies examining school-aged children indicate that age has the opposite effect amongst children; younger children tend to feel greater connectedness than older children (Liefländer et al., 2013; Braun and Dierkes, 2017; Crawford et al., 2017; Larson et al., 2018). These opposing patterns suggest a curvilinear effect whereby children temporarily grow-out of their connection to nature, so to speak, until at some point they begin to reformulate their connection to nature. At present, this pattern has been supported by one study specifically seeking to sample a range of ages to address the question of age’s impact on connectedness more comprehensively (Hughes et al., 2019).

When gender differences in connectedness are found, they appear to more often conclude that women feel greater connectedness than men (Schultz and Tabanico, 2007, S3–4; Mayer et al., 2009, S2; Bruni and Schultz, 2010, S3; Beery, 2013; Sanguinetti, 2014; Zhang et al., 2014b, S1; Pensini et al., 2016; Spendrup et al., 2016; Swami et al., 2016; Crawford et al., 2017; Nour et al., 2017; Hughes et al., 2019) than they report that men feel more connectedness than women (Larson et al., 2018; Wyles et al., 2019). However, a number of studies that provide information about the associations between gender and connectedness report no effect (Mayer and Frantz, 2004, S1–2; Frantz et al., 2005; Bruni et al., 2008; Mayer et al., 2009, S1 and S3; Weinstein et al., 2009, S1–3; Bruni and Schultz, 2010, S1–2; Duffy and Verges, 2010; Vess et al., 2012; Zhang et al., 2014b, S2; Barton et al., 2016; Davis and Stroink, 2016a,b; Harvey et al., 2016; Unsworth et al., 2016, S1–2; Lumber et al., 2017; Di Fabio and Kenny, 2018; Diessner et al., 2018; Liu et al., 2019; Whitburn et al., 2019). Additionally, there is no evidence that gender moderates any effects in any of the studies reporting on gender and connectedness (e.g., Mayer et al., 2009; Duffy and Verges, 2010; Vess et al., 2012; Capaldi et al., 2014). Thus, the conclusion to be drawn from the literature is that, if gender has an effect at all—a tenuous association at best—women may feel greater connectedness than men.

There are three understudied demographics—education, race, and socioeconomic status—which may be worth further attention. Several studies have found that level of education does not have an effect on connectedness (Mayer and Frantz, 2004, S1; Dutcher et al., 2007; Beery, 2013; Walters et al., 2014; Nour et al., 2017; Whitburn et al., 2019); however, other studies have found higher education to be associated with lower connectedness (Sanguinetti, 2014; Brown, 2017). Similarly, a small number of studies have found no relationship between race and connectedness (Weinstein et al., 2009, S1–3; Whitburn et al., 2019), while one found that white participants report a sense of connectedness more so than non-white participants (Larson et al., 2018). And, again similarly, while studies have suggested no relationship between connectedness and socioeconomic status (Wyles et al., 2019) or income (Mayer and Frantz, 2004; Dutcher et al., 2007; Beery, 2013; Walters et al., 2014), yearly income and home ownership have been associated with decreased connectedness (Whitburn et al., 2019). Thus, based solely on the literature appearing in this review, it would be premature to draw conclusions about the effect of level of education, race, and socioeconomic status on connectedness.

As might be expected, people who hold more positive environmental beliefs feel greater connectedness (Mayer and Frantz, 2004, S1–2; Frantz et al., 2005; Nisbet et al., 2009, S1; Bruni and Schultz, 2010; Clayton et al., 2011, S1; Davis et al., 2011; Brick and Lewis, 2014; Lee et al., 2015; Davis and Stroink, 2016a,b; Whitburn et al., 2019). Additionally, higher levels of connectedness are found among individuals who tend to appreciate natural beauty (Zhang et al., 2014b, S1–2; Capaldi et al., 2017, S1–2; Lumber et al., 2017; Diessner et al., 2018), are more politically liberal (Dutcher et al., 2007; Nour et al., 2017), and are more empathic (Mayer and Frantz, 2004, S2 and S4; Di Fabio and Bucci, 2016; Di Fabio and Kenny, 2018). Lower levels of connectedness are found among those who are more politically conservative (Brick and Lewis, 2014) more authoritarian (Nour et al., 2017), more oriented toward consumerism (Mayer and Frantz, 2004, S4) or materialism (Hedlund-de Witt et al., 2014), and who ascribe to the feminine beauty ideal (Scott, 2010, S1–2). In general, individual’s values seem to be associated with connectedness (Sellmann and Bogner, 2013; Lumber et al., 2017), an effect which may be initially derived from parent’s values (Cheng and Monroe, 2012). There is also evidence that religious fundamentalism is negatively associated with connectedness; however, this was only under conditions of mortality salience (Vess et al., 2012), whereas more general religiosity or spirituality may have either no (Vess et al., 2012, S1–3, but see Brown, 2017) or a positive effect on connectedness (Hedlund-de Witt et al., 2014).

Connectedness also shows positive associations with constructs that support the perspective that connectedness reflects a form of self-transcendence. Specifically, connectedness is positively associated with self-transcendent values and negatively associated with self-enhancement values (Tam, 2013). Further, connectedness is positively associated with constructs involving connecting to something greater, such as connectedness to community (Sanguinetti, 2014) and even to humanity as a whole (Lee et al., 2015; Lengieza et al., 2021), as well as with greater moral expansiveness (Crimston et al., 2016) and more altruism (Nisbet et al., 2009, S1). Moreover, connectedness is positively associated with non-self-interested concern for nature (e.g., biospheric concern; Mayer and Frantz, 2004, S4–5; Davis and Stroink, 2016a,b; although this effect is sometimes not found, e.g., Schultz and Tabanico, 2007, S2; Duffy and Verges, 2010) whereas, at best, connectedness is simply not associated with self-interested concern for the environment (e.g., egoistic concern; Mayer and Frantz, 2004, S4; Schultz and Tabanico, 2007, S1–2; Duffy and Verges, 2010; Davis and Stroink, 2016a,b) and, at worst, may be negatively associated with such self-centered concern (Mayer and Frantz, 2004, S5; Schultz and Tabanico, 2007, S1). Lastly, individuals who think more in terms of systems—which is related to seeing oneself as part of a set of interrelated parts and suggestive of self-transcendence (c.f., Lengieza et al., 2021)—tend to report higher levels of connectedness (Davis and Stroink, 2016a). Thus, there is evidence that constructs consistent with self-transcendence (e.g., self-transcendence values; Tam, 2013) are associated with connectedness which supports the contention that connectedness reflects a form of self-transcendence (e.g., Lengieza et al., 2021).

The obvious consensus in the literature—largely informed by the results of the meta-analysis (i.e., Schutte and Malouff, 2018)—is that the psychological experience of mindfulness is associated with increased connectedness. This association in conjunction with the evidence that meditation also increases connectedness, seems to suggest that changes in mindfulness would mediate the relationship between meditation and connectedness. To date, however, this process of mediation has not been empirically tested. Thus, future research should attempt to document the process through which meditation increases connectedness. Such an endeavor will entail paying greater attention to various facets of mindfulness to fully understand the relations between meditation, mindfulness, and connectedness.

It is also possible that mindfulness is not the only path through which meditation increases connectedness; perhaps meditation also influences connectedness through an effect on the way we think about the self (c.f., Hanley et al., 2017) through an effect on affective experiences (c.f., Jazaieri et al., 2013), or simply through increased reflective or introspective propensity (c.f., Richardson and Sheffield, 2015; see ensuing sections for elaboration). Consequently, research investigating the process through which meditation has its effect should consider alternative mechanisms in addition to mindfulness.

Self-awareness, with its different facets, is one such self-related phenomena that affects connectedness. Studies suggest that taking oneself as the object of awareness might negatively impact connectedness. In one study, self-objectification—taking the critical perspective of an observer when considering the self—was negatively associated with connectedness across three samples of women (Scott, 2010). Another study demonstrated that being seated in front of a mirror—which theoretically increases objective self-awareness—diminished connectedness (Frantz et al., 2005). This suggests that objective self-awareness may interfere with connectedness.⁴

Other studies corroborate the findings from research on objective self-awareness. Evidence suggests that being publicly self-aware—being more aware of how you appear to others—is negatively associated with connectedness (Mayer et al., 2009). In line with the negative association with public self-awareness, rumination—which was defined as anxious, or preoccupied, attention that is focused on the self and is concerned with self-worth or failure (making it similar to public self-awareness)—was negatively correlated with connectedness (Richardson and Sheffield, 2015). Further, research suggests that decreases in public self-awareness may be the mechanism through which contact with nature increases connectedness (Lengieza and Swim, 2021). Thus, being overly focused on oneself from a third-person perspective seems to have a negative impact on connectedness.

In addition to research on self-awareness, other evidence implies that diminishing overly self-focused attention may be important for facilitating connectedness. First, some studies investigating mindfulness implicate the self as an important determinant of connectedness; one of the reasons that mindfulness may influence connectedness is because of its effect on decentering (Hanley et al., 2017; see also Nisbet et al., 2019). Specifically, decentering has been argued to be linked with self-transcendence and to a blurring of the self–other dichotomy (Hanley et al., 2018). Thus, the link between decentering and connectedness is consistent with the defining connectedness as a form of self-transcendence (Lengieza et al., 2021). Second, one of the reasons that psilocybin increases connectedness may be because of the effect it has on individual’s sense of self; ego dissolution—a pharmacologically induced state of selflessness associated with psychedelics—during individuals’ most significant experience with psilocybin was associated with increased connectedness (Nour et al., 2017). Thus, this evidence would loosely suggest that diminishing attention to the self might promote connectedness.

There is other evidence that which implicate the self in the formation of connectedness and also suggests that the self might not always be an obstacle in the way of forming a connection with nature. In contrast to objective self-awareness and public self-awareness, private self-awareness—being aware of one’s inner experience, effectively synonymous with introspection—may enhance connectedness (Mayer et al., 2009). Consistent with this finding, reflective self-attention was found to be a better predictor of connectedness than mindful attention (Richardson and Sheffield, 2015, S1–2) and moderated the effect of exposure to nature, with higher levels of reflective self-attention strengthening the effects of contact with nature on connectedness (Richardson and Sheffield, 2015, S3). Additionally, as noted above, one of the mechanisms through which VR might increase connectedness may be body transference (Ahn et al., 2016, S1–3); in other words, a transfer of our corporeal sense of self seems to influence connectedness. Fourth, the ways in which we construe the self (e.g., interdependent, independent, etc.) seem to influence connectedness (Davis and Stroink, 2016b) as does the way that we feel about ourselves (i.e., self-esteem; Zhang et al., 2014b, S2; Swami et al., 2016). Thus, there is growing evidence that self-related phenomena are, at the very least, an important part of the formation of connectedness.

The above evidence concludes that self-related phenomena play a critical role in the formation of connectedness. Specifically, both the way in which we attend to the self (e.g., Richardson and Sheffield, 2015) and the way we subjectively experience the self (e.g., Hanley et al., 2017; Nour et al., 2017) influence connectedness, though there is still much of this story left to untangle.

This means, however, that there are many exciting directions for future research in this area. First, there are several additional phenomena related to the self that may impact individuals’ sense of connectedness such as goal-related content (e.g., actual, ideal and ought selves; Higgins, 1987) temporal reflections (e.g., past, present and future selves; Markus and Nurius, 1986) and structure of the self (e.g., self-schemas, Markus, 1977). The growing evidence that the self influences connectedness in multiple ways suggests that the unstudied associations between these facets of the self and connectedness warrants future investigation.

Second, there are opportunities to further differentiate already-studied phenomena (c.f., public vs. private self-awareness) to create more nuanced accounts of how self-related psychological states are expected to impact connectedness. As an example, the observation of a positive association between connectedness and private self-awareness in contrast to the negative association with public self-awareness suggests that these two types of self-awareness should be differentiated. Moreover, these specific opposing relations raise two interrelated points. (A) These opposing effects emphasize that more research is necessary to understand when focusing on the self diminishes connectedness and when it might benefit it. (B) It seems to tentatively suggest that what gets in the way of connecting to nature is a disproportionate (e.g., Lengieza and Swim, 2021) and preoccupied (e.g., Richardson and Sheffield, 2015) focus on the self—as opposed to an introspective or proportionate focus on the self (e.g., Richardson and Sheffield, 2015). In other words, in the context of its relation to connectedness, there may be such a thing as a healthy and unhealthy focus on the self.

Third, there is the opportunity to use research on the self to inform research on the antecedents of connectedness. For example, it is worth considering how self-related psychological states might mediate relations described in earlier sections. One could test, as suggested above, whether decentering—which tentatively links mindfulness to connectedness (e.g., Hanley et al., 2017)—is one of the avenues through which meditation affects connectedness. Further, it is also worth considering how other, yet-studied, situations or interventions that are believed to influence the self might be related to changes in connectedness. For example, body scan meditation has been shown to induce a blurring of the self-other boundary (Dambrun, 2016), thus studying the effect on connectedness that this type of intervention has might warranted solely on the basis that it influences the self.

Affect may be an important determinant of connectedness. Positive affect has been shown to (e.g., Nisbet and Zelenski, 2011) promote connectedness, whereas negative affect appears to suppress it (e.g., Nisbet et al., 2011). For the most part, however, few studies consider affect and emotions with increased granularity. That is, most studies treat positive affective states and negative affective states as cohesive groups. Affective states, however, differ on more than just valence (e.g., approach–avoidance; Harmon-Jones et al., 2017) and it may be worthwhile to understand how certain classes of emotions affect connectedness (e.g., awe as a type of self-transcendent emotions; Stellar et al., 2017) as there is evidence that different types of positive affect differentially predict connectedness (Lengieza et al., 2021).

While contact with nature seems to be an important determinant of connectedness only one study appeared in this review that compared different types of contact with nature within the same study (e.g., Wyles et al., 2019). There are a number of dimensions on which nature can vary—from manicured to wild, from green to blue to gray, from novel to familiar, etc.—and it would be valuable to know, for the same general reasons listed in the preceding mindfulness example, if and how these dimensions might matter.

Research on self-awareness would also benefit from increased consideration of the nuances between types of self-awareness. Specifically, it seems that public and private self-awareness have opposing effects on connectedness (e.g., Mayer et al., 2009), suggesting that there may be a type of focus on the self that is beneficial and a type of focus on the self that is not. However, at present, no research has truly addressed this question systematically.

Research on affect and connectedness may also benefit from differentiating between various forms of affect. As the literature currently stands, positive affect promotes, whereas negative affect diminishes, connectedness (e.g., Nisbet et al., 2011). There is reason to believe, however, that not all positive affect will affect connectedness in the same way; (e.g., eudaimonic vs. hedonic affect; Lengieza et al., 2021). Thus, it may be worthwhile to consider more nuanced distinctions between similar types of emotions.