Introduction
Research on serotonergic psychedelics has accelerated in the last decade (Carhart-Harris and Goodwin, 2017) due to promising demonstrations of psychotherapeutic effects, and relaxed legal restriction on scientific investigation (Nutt et al., 2013). Research in this area has mainly focused on contributions to individual utility, including gains in personal well-being (e.g., Griffiths et al., 2011), personality (e.g., Erritzoe et al., 2018), and remediation of mental health disorders including alcohol misuse (Bogenschutz et al., 2015), major and resistant depression (e.g., Carhart-Harris et al., 2016a, 2021; Davis et al., 2020), and end of life anxiety/depression (e.g., Griffiths et al., 2016). A smaller and growing area of psychedelic research has explored how psychedelic compounds may confer value to both individuals and collectives through such outcomes as enhanced cooperation, trust, and social connectedness within interpersonal systems (referred to here as collective functioning).
Collective functioning can conceivably be enhanced directly through mutual participation in group-format psychedelic experiences (e.g., ayahuasca ceremony, group recreation; e.g., Kettner et al., 2021), and/or indirectly via the development of traits in individuals related to social functioning. The present study focuses on the latter path, wherein the link between psychedelic use and collective functioning may be mediated by enhanced social functioning at the individual level. Social functioning is defined as the ability to fulfill important roles within environments of social activity, work, and relationships (Bosc, 2000), but will be used more broadly here to describe personality traits that subserve harmonious relationships including empathic ability, prosociality, low anger reactivity, and moral reasoning. Improved social functioning is assumed to promote positive individual and collective outcomes through augmenting interpersonal trust, social connectedness, relationship longevity, and emotional fulfillment in social interaction. The purpose of this study is to investigate the degree to which naturalistic use of psychedelic compounds results in adaptive changes in personality traits relevant to social functioning and perceived social connectedness. Because personality change effects may depend on other measurable factors, we also examine the degree to which predisposing factors, such as demographic characteristics and baseline personality, and acute subjective factors, such as non-ordinary states of affect and consciousness during psychedelic experience, moderate changes.
A useful framework for our examination lies in the Five-Factor Model (FFM; Costa and McCrae, 1992) of personality, which includes three personality domains that possess empirical support for subserving social functioning. Neuroticism describes a disposition toward negative emotionality and stress reactivity; Extraversion describes a disposition toward positive emotionality, reward sensitivity, and receiving social attention; and Agreeableness describes a prosocial and communal (versus antagonistic) tendency to be considerate of others’ needs, desires, and feelings, and is neurocognitively associated with social information processing (e.g., DeYoung, 2010; DeYoung et al., 2010). In the context of relationships, low Extraversion (being withdrawn) and low Agreeableness are associated with peer rejection (Newcomb et al., 1993), and higher levels of Extraversion are associated with social acceptance and network size, popularity, and dating variety (e.g., Anderson et al., 2001; Paunonen, 2003; Feiler and Kleinbaum, 2015). In the context of romantic relationships, Agreeableness has shown relations with relationship satisfaction (e.g., Cramer and Jowett, 2010; Kimmes et al., 2014). Consistent with this, Neuroticism and low Agreeableness have shown predictive relations with relationship dissatisfaction, conflict, and dissolution (e.g., Karney and Bradbury, 1995; Donnellan et al., 2004; Weiss et al., 2018), outcomes thought to be mediated by a positive feedback loop involving negative emotion and relationship distress (Robins et al., 2002).
In the context of larger groups, Agreeableness and Extraversion has been found to be related to cooperation, and Agreeableness shows evidence of being inversely related to hypercompetition (Ross et al., 2003). Agreeableness may be most relevant to social and collective functioning as it involves higher functioning in empathy, a disposition toward prosociality (or antisociality at its opposite pole), and is associated with relationship stability. Agreeableness bears substantial overlap with affective and cognitive empathy, which, respectively, describe capacities to infer the emotional experience of others and to occupy the mental perspectives of others (e.g., Melchers et al., 2016). Agreeableness was also found to be elevated among young adult moral exemplars (Matsuba and Walker, 2004). At its opposite pole, low Agreeableness (or Antagonism) is thought to reflect the core of personality disorders such as Narcissistic Personality Disorder, Antisocial Personality Disorder, and psychopathy (e.g., Widiger et al., 2012), as well as Antagonistic Externalizing, one of two Externalizing spectra within the Hierarchical Taxonomy of Psychopathology (Kotov et al., 2017), a data-driven and integrative model of psychopathology. Antagonistic Externalizing describes tendencies toward engaging in criminal and antisocial acts involving theft, destruction of property, physical aggression toward others, and violations of rules of conduct (Widiger et al., 2012; Kotov et al., 2017). In sum, Neuroticism, Extraversion, and Agreeableness may be particularly relevant targets of inquiry when examining the effects of psychedelic compounds on social functioning.
There are four sources of empirical evidence that best inform the presence of a link between psychedelic use and enhanced social functioning. These include literature examining the effects of psychedelic compounds on FFM personality, social cognition, social connectedness, and moral behavior. The most relevant evidence to the present study is located in the personality literature. Eleven studies have prospectively examined long-term psychedelic-induced change in personality (e.g., MacLean et al., 2011; Madsen et al., 2020). Of these studies, five have shown evidence of adaptive change in Neuroticism or convergent constructs [e.g., Temperament and Character Inventory Harm Avoidance (characterized by worry)] (e.g., Barbosa et al., 2009; Erritzoe et al., 2018). Two studies have shown evidence of self-reported change in Extraversion (Erritzoe et al., 2018; Weiss et al., 2021), with change notably reflected in facets relevant to social functioning (Warmth/Friendliness, Gregariousness). Lastly, three studies have shown qualified evidence of increased Agreeableness (Carhart-Harris et al., 2016b; Netzband et al., 2020; Weiss et al., 2021). Although peripherally relevant to our focus on social functioning, seven studies have found evidence for change in Openness (e.g., MacLean et al., 2011; Rocha et al., 2021; Weiss et al., 2021), whereas only one has found evidence of change in Conscientiousness (Barrett et al., 2020). Of note, some studies have found no meaningful evidence of longer-term change in personality (e.g., Schmid and Liechti, 2018; Rocha et al., 2021). In addition, numerous clinical studies, including randomized placebo-controlled trials, have provided support for an antidepressant effect (Andersen et al., 2021). Given that many psychopathological symptoms are increasingly conceptualized as maladaptive variants of basic personality dimensions and share the same structure (Widiger et al., 2012; Kotov et al., 2017), these latter results may be relevant to change in FFM Neuroticism and Extraversion. In sum, long-term psychedelic-induced changes in personality domains relevant to social functioning have been observed, but findings remain somewhat inconsistent. This inconsistency is likely to stem from multiple sources including study variability in sample size, sample type (general population, clinical, healthy), length of follow-up, conditions of administration, and inner experiences during the acute effects of the compounds. One major limitation of the existing literature is that sample size for prospective studies has been low (N=25), making it difficult to arrive at precise estimates of change (given high standard error), or to examine moderating factors predictive of change (given insufficient statistical power).
The second source of evidence lies in the area of social cognition. Existing findings are suggestive that psychedelic compounds modulate social cognition for up to a week following use. Specifically, behavioral and neurophysiological findings have shown that 5-HT2A receptor agonists acutely produce attenuated processing of social rejection (based on self-report and dorsal anterior cingulate cortex; Preller et al., 2016) and negative facial expressions (based on self-report and N170, P300 evoked-response-potential; Kometer et al., 2012; Dolder et al., 2016), which may be suggestive of downstream emotional resilience in social settings, greater levels of social approach, and lower avoidance. Studies have also been supportive of acute increases in emotional empathy (Dolder et al., 2016; Holze et al., 2021a). More recent research has shown evidence of post-acute changes in amygdala blood oxygen-level dependent response to emotional face stimuli, though the directionality of effects has differed across studies. One study showed reduced amygdala activations lasting at least a week following acute effects, but not longer than 1month (Barrett et al., 2020). Another, examining patients with treatment-resistant depression, showed increased amygdala activations one day post dosing with psilocybin (Roseman et al., 2018). Collectively, these findings suggest that psychedelic compounds alter social cognition-related neural functioning sub- and post-acutely.
A third source of evidence observes changes in perceived social connectedness during and following psychedelic experience, a phenomenon that may be linked to changes in social cognition just described. In a large cross-sectional examination of festival-goers, Forstmann et al. (2020) showed that psychedelic compounds were unique among substances in producing increased perceptions of social connectedness with other human beings broadly and with fellow event attendees. However, these effects obtained only for participants who endorsed using psychedelic compounds within the preceding 24h, but not earlier, suggesting that social connectedness effects may be temporary. Although long-term changes in self-reported interpersonal closeness were found 6months following the acute effects of psilocybin in one study (Griffiths et al., 2018), these findings remain tentative in view of failure to find a significant difference from the control group. Findings of increased perceived social connectedness are consistent with at least two sources of qualitative data demonstrating an enhanced sense of connectedness to significant others and other human beings, marked by openness to others, sociability, and authentic expression (Belser et al., 2017; Watts et al., 2017). Changes in perceived social connectedness may also be one manifestation of a general sense of connectedness that is described in qualitative reports (Belser et al., 2017) and instantiated in measures of mystical-type experience [i.e., unitive consciousness (or a sense of “oneness” or “unity”)].
A fourth source of evidence involves a small body of literature investigating whether psychedelic compounds promote moral reasoning and prosocial behavior. Findings from this body of literature have however been strongly mixed. Among the supportive findings, there is evidence of a long-term self-reported increase in altruism and positive social effects from three small prospective studies (Dolder et al., 2016; Griffiths et al., 2018; Schmid and Liechti, 2018), the latter of which demonstrated changes over and above a control group. Furthermore, in two large observational samples of criminal offenders, a diagnosis of hallucinogen use disorder was predictive of lower recidivism, violations of supervisory rules in a correctional setting, and future arrests involving intimate partner violence (Hendricks et al., 2014; Walsh et al., 2016). These findings may be suggestive of long-term reductions in Antagonistic Externalizing and Antagonism following psychedelic use. Nevertheless, despite being prospective studies, it is conceivable that other explanations can account for these observations, most notably that participants inclined to use psychedelic compounds already differed from other participants on traits associated with these outcomes before using. These findings stand in contrast to others that fail to support a link between psychedelic use and moral reasoning or behavior.
Although the 5-HT receptor system shows evidence of an involvement in harm aversion (self & other) and deontological (versus utilitarian) moral reasoning (Crockett et al., 2010, 2015), 5-HT2A receptor agonists were not associated with greater aversion to harm others in the only existing examination containing a social moral dilemma task (though sample size was low, N=33; Pokorny et al., 2017). Furthermore, when offered the opportunity to express prosocial behavior through the allocation of redeemable lottery tickets and money to strangers, psychedelic users (within the aforementioned festival context) were no more likely to do so than other participants (Forstmann et al., 2020). Psychedelic users in this context also did not differ from others in ascribing moral praiseworthiness to deeds on the basis of the value of the deed’s outcome for others (versus the hedonic value of the deed for the agent). These findings are also consistent with null observer-rated changes in interpersonal perceptiveness, caring, anger expression, and compassion/social concern in a small prospective study (Griffiths et al., 2018). In sum, evidence is mixed with respect to psychedelic-induced improvements in moral reasoning and prosocial behavior. It may also be possible that substantive change occurs selectively in individuals higher in Antagonism (i.e., low Agreeableness).
The present study builds upon these findings through examining change in FFM personality domains relevant to social functioning as well as perceptions of social connectedness in a sample of 148 individuals recruited online. Our naturalistic approach enabled the collection of a larger sample through greater cost-effectiveness relative to laboratory-based studies, and provides an opportunity to gain insight into the effects of psychedelic use in the general population. Understanding how psychedelic experiences unfold outside of a controlled laboratory or shamanic setting—where harm reduction practices may be lacking—is ethically important as decriminalization/legalization policies expand use above and beyond already high prevalence in the West (Krebs and Johansen, 2013a,b; Winstock, 2017). In our study, a web-based survey—embedded within a purpose-built website—was used to measure outcomes and relevant moderators across five timepoints—including (1) 1week before, (2) within 1day before, (3) within a few days after, (4) 2weeks after, and (5) 4weeks after a psychedelic experience—among which study outcomes were measured 1week before, 2weeks after, and 4weeks after. Using an integrated FFM framework, we also included outcomes conceptually and empirically related to FFM domains (e.g., measures of compassion and affective empathy enrich measurement of FFM Agreeableness). Our first aim was to examine change in personality traits related to social functioning and perceptions of social connectedness, as well as covariance between these sets of outcomes over time. We focused on Neuroticism, Extraversion, and Agreeableness in view of their relevance to social functioning. FFM Openness and Conscientiousness were also examined for comprehensiveness. In line with previous empirical and theoretical work (MacLean et al., 2011; Carhart-Harris et al., 2016b, 2021; Erritzoe et al., 2018; Forstmann et al., 2020; Netzband et al., 2020; Weiss et al., 2021) FFM Extraversion, Openness, Agreeableness, and perceived social connectedness were hypothesized to increase, and FFM Neuroticism was hypothesized to decrease following initial measurement.
Our second aim was to investigate factors that may potentiate or suppress personality change in relation to psychedelic experience. Few studies to date have rigorously examined potential moderators of change (e.g., subjective acute experiences, baseline personality) which may account for inconsistency in the literature and/or provide necessary conditions for change. Specifically, we examined the degree to which differences in FFM domains between timepoints varied as a function of an array of predisposing and acute factors. Predisposing factors relate to individual characteristics as well as psychological states, and spatial, temporal, and social contexts that may influence the nature of an individual’s experience. Acute factors relate to subjective psychological states arising under acute psychedelic effects. In line with previous work (MacLean et al., 2011; Erritzoe et al., 2018; Weiss et al., 2021), mystical-type experience was hypothesized to contribute to a larger difference in FFM Neuroticism, Extraversion, and Openness following 2weeks and 4weeks post-experience.
Discussion
Meaningful prosocial changes were observed across a number of outcomes relevant to social functioning. Overall, participants reported decreases in critical and quarrelsome demeanor and anxiety and mood lability, and increases in perceived social connectedness. Preliminary evidence was additionally found for increases in cognitive empathy, but only among participants initially low in this trait. Adaptive changes in neuroticism and perceived social connectedness also showed signs of being amplified among participants starting with less adaptive initial levels of these traits. We expand upon these findings within the context of four main questions: (a) Is psychedelic use related to changes in personality traits relevant to social functioning? (b) Is psychedelic use related to change in perceptions of social connectedness? (c) Is change in personality connected to change in perceived social connectedness? and (d) Are there factors that predispose or potentiate change in social functioning-related traits and perceived social connectedness?
Is Psychedelic Use Related to Changes in Personality Traits Relevant to Social Functioning?
Two personality domains with strong relevance to social functioning (neuroticism, agreeableness) displayed substantive, small-sized, changes in the direction of enhanced social functioning. First, agreeableness was measured using four outcomes including TIPI Critical Quarrelsome, TIPI Sympathetic Warm, compassion, and empathic concern. TIPI Critical Quarrelsome was the only outcome to decline substantively between baseline measurement and 2weeks following psychedelic experience and remain substantively below baseline scores 4weeks following use. Although limited internal reliability for this single-item outcome qualifies interpretation, this result is suggestive of components of agreeableness that are particularly susceptible to psychedelic change processes. According to the Big Five Aspects model (BFAS; DeYoung et al., 2007), a data-driven model of personality, each FFM domain can be divided into two distinct, but interrelated, components that hold superior parsimony relative to FFM facets, and greater granularity relative to broad FFM domains. For agreeableness, these components represent aspects Compassion (versus Callousness) and Politeness (versus Belligerence). Notably, TIPI Critical Quarrelsome is the only measured outcome that, based on rational analysis, conceptually captures the Politeness aspect of agreeableness, whereas the other agreeableness outcomes capture the Compassion aspect. At its low pole, Politeness, like the TIPI Critical Quarrelsome item, describes an antagonistic and conflict-prone style of interpersonal relating that seeks to express judgment, demonstrate superiority, and gain advantage.
Our results are the first in the literature to suggest a specific decrease in criticism and quarrelsomeness following psychedelic experience. Should psychedelic experience be most targeted to personality functioning in Politeness, it bears noting the clinical and forensic implications of this finding. Politeness, relative to Compassion, bears strongest relations with pathological personality traits most relevant to antagonistic personality disorders (e.g., Narcissistic Personality Disorder, Antisocial Personality Disorder) including attention seeking, grandiosity, manipulativeness, deceitfulness, and hostility (e.g., DeYoung et al., 2016). As such, in this data, psychedelic use shows some signs of therapeutic potential for the treatment of personality disorders. Our data appears consistent with three studies that have shown qualified support for prospective increases in agreeableness (Carhart-Harris et al., 2016b; Netzband et al., 2020; Weiss et al., 2021), as well as work showing decreased levels of supervision failure among individuals involved in the justice system and intimate partner violence in the general population (Hendricks et al., 2014; Thiessen et al., 2018).
No other agreeableness outcomes exhibited meaningful change. One explanation for these results relates to restriction of range in these outcomes versus TIPI Critical Quarrelsome, such that participants in our sample tended to exhibit already above-average standing on TIPI Sympathetic Warm, compassion, and empathic concern, and thus may have possessed less potential for upward change in these traits (see Supplementary Figure S2 for baseline density plots). Moderation analyses were accordingly conducted to examine whether participants with lower scores on these traits were more likely to exhibit significant upward change. No credible moderation was observed. Power analyses were additionally conducted to evaluate our capacity to form conclusions from these null results, namely that TIPI Sympathetic Warm, compassion, and empathic concern do not meaningfully respond to naturalistic psychedelic use. The results of our power analyses were suggestive that we were adequately powered to detect an interaction effect of small size (b<0.20) for compassion and empathic concern if one was present. As such, our data provide preliminary support for the absence of meaningful longer-term change in compassion and empathic concern in the general population of psychedelic users. Furthermore, our null results with respect to adaptive change in affective empathy (indexed by IRI Empathic Concern) are convergent with previous evidence that explicit emotional empathy (a related construct) does not remain enhanced for longer than 1week following psychedelic administration (Mason et al., 2019).6 It is notable that acute increases in explicit emotional empathy have been observed in three previous studies using the Multifaceted Empathy Test (MET; Dziobek et al., 2008) (Dolder et al., 2016; Pokorny et al., 2017; Mason et al., 2019). This raises the possibility that enhancements in affective empathy and compassion may be time-limited without additional maintenance practices.
Finally, perspective taking, a related construct capturing cognitive empathy (i.e., ability to occupy mental perspectives of others; IRI Perspective Taking), did show some signs of increasing in relation to psychedelic use for a subset of our sample. Although a main effect change in perspective taking was not observed, participants one standard deviation below the mean in baseline perspective taking exhibited substantive change in this trait. Although the measure we used involved subjective self-appraisal, our results provide preliminary evidence that psychedelic use may provide longer-term enhancements to cognitive empathy among individuals with low initial capacity. Of note, however, Mason et al. (2019) did not observe enhanced cognitive empathy 7days post-psychedelic experience while using the MET cognitive task. We encourage researchers to examine whether a similar subset of individuals with low standing on cognitive empathy exhibit substantive post-acute enhancements in objective task performance.
Collectively, this pattern of results may be suggestive that psychedelic experience in the general population is more likely to drive adaptive changes in Politeness versus Compassion. On a methodological level, the pattern raises the possibility that mixed findings within the literature may owe in part to imprecise measurement of agreeableness. Future research is accordingly called for that examines psychedelic-induced personality change using granular measurement sufficient to detecting possible differential effects on aspects (or facets) of personality.
Second, perhaps strongest support was found for adaptive change in neuroticism, with data showing small-sized, but substantive decreases in anxiety and mood lability (TIPI Anxious Easily upset) that remained significantly above baseline scores 4weeks following psychedelic use. Our results are consistent with a number of previous prospective studies showing psychedelic-induced reductions in neuroticism (Barbosa et al., 2009; Fernández et al., 2014; Erritzoe et al., 2018) including one study demonstrating change relative to a control group (Netzband et al., 2020) and a naturalistic study showing change in self- and informant-report data (Weiss et al., 2021). Three randomized and controlled clinical trials (Palhano-Fontes et al., 2019; Davis et al., 2020; Carhart-Harris et al., 2021) also provide support for a psychedelic-induced antidepressant effect, which bears relevance to our present examination of neuroticism in view of common structure between personality and psychopathology (e.g., Widiger et al., 2012; Kotov et al., 2017). Of note, the size of the observed effects are somewhat smaller than medium-sized effects found in other studies (e.g., Erritzoe et al., 2018; Weiss et al., 2021). As such, recreational use outside of therapeutic contexts designed to support introspective inquiry (e.g., psychedelic-assisted therapy, ayahuasca ceremony) may attend smaller effect size changes. Increased emotional stability (TIPI Calm Emotionally stable) was only observed between baseline and 2weeks, and thus will not be interpreted. Similarly, because changes in TIPI extraversion did not extend to 4weeks, and its counterpart item, TIPI Reserved, showed no change, this result is not interpreted.
Collectively, our results indicate that psychedelic use may promote personality traits of high relevance to social functioning, namely traits linked to lower reactivity and antagonism in interpersonal communication, relationship stability, and emotion regulation. Results involving decreased neuroticism may be consistent with recent neurocognitive work demonstrating reduced negative affect (and amygdala response) in relation to facial stimuli 1week following psilocybin use, and decreased trait anxiety and increased positive affect 1month following psilocybin use (Barrett et al., 2020).
To evaluate the size of these personality change effects relative to alternative interventions, we additionally compared observed effect size changes in TIPI Anxious and TIPI Critical to meta-analyzed effects of psycho- and pharmacotherapeutic intervention. In their large meta-analysis (k=199; N=~20,000), Roberts and colleagues (2017) observed that neuroticism declined and agreeableness increased by 0.57 and 0.15 standard deviations, respectively, in relation to 24week (on average) clinical interventions.7 When calculated in an equivalent manner in our sample (N=249), TIPI Anxious exhibited a lower effect size change, namely a reduction of 0.26 standard deviations; whereas TIPI Critical exhibited a larger effect size change, namely a decrease of 0.27 standard deviations. These results may be suggestive that psychedelic use in the general population does not carry the therapeutic effectiveness for reducing neuroticism that can be found in clinical intervention or in other contexts (e.g., psilocybin-assisted therapy, Erritzoe et al., 2018; ayahuasca ceremony, Weiss et al., 2021), but such use may accompany enhanced effectiveness for enhancing agreeableness (or reducing antagonism). Nevertheless, it is important to bear in mind that Roberts and colleagues’ (2017) meta-analysis likely included a small proportion of studies targeting agreeableness specifically, potentially suppressing their observed effect size for agreeableness, and making our effect size estimates appear artifactually favorable.
Although speculative, it may be additionally useful to explore the degree to which the trajectories of change in personality found in this study relate to each other. Covariance of change over time may be diagnostic of common psychedelic-induced processes that underlie multiple traits. To accomplish this goal, we conducted analyses examining correlations of change scores in those traits that exhibited significant change in our study (Table 6). Notably, TIPI Anxious exhibited a medium-sized correlation with TIPI Critical.8 Such intraindividual covariation of neuroticism and agreeableness following psychedelic experience may point to lower critical and quarrelsome disposition under psychological conditions of reduced negative emotionality. This relation may also point to common causes involving enhanced emotion regulation ability (e.g., regulation of distress and frustration). Few studies have explored these possibilities in particular. Nevertheless, one previous study showed that men with a history of psychedelic use reported better emotion regulation ability and lower intimate partner violence, and that emotion regulation ability cross-sectionally mediated the relation between psychedelic use and intimate partner violence (Thiessen et al., 2018). Applied to our own work, it is conceivable that reduced neuroticism via enhanced emotion regulation accompanies lower stress reactivity and interpersonal aggression, as indexed by our TIPI Critical Quarrelsome item. It will be important for future prospective work to explore how psychedelic use may mechanistically impact BFAS Belligerence (low pole of Politeness) and externalizing behavior, possibly through enhanced emotion regulation, meaning, and fulfillment, and reduced negative emotionality and anger reactivity.
Is Psychedelic Use Related to Change in Perceptions of Social Connectedness?
Our focus on connectedness to other human beings is part of a larger effort to explore the ways in which psychedelic use may engender enhanced connectedness, broadly construed (Carhart-Harris et al., 2018). Such connectedness is thought to be evident in acute ego dissolution experience by which the coherent self becomes diminutive within awareness and most clearly in acute mystical experiences of oceanic boundlessness and external unity by which one experiences unification with external objects and entities (Barrett et al., 2015). Previous research has shown that psychedelic-induced connectedness also extends to self (Watts et al., 2017), nature (e.g., Forstmann and Sagioglou, 2017; Lyons and Carhart-Harris, 2018) and other human beings (Forstmann et al., 2020). Increases in perceived social connectedness was found using both of our operationalizations: a semantic face-valid measure and a visual measure that asked participants to select the degree of overlap between self and other that best represents their current relationship with other human beings. However, we only interpret changes in SCS Social Connectedness, capturing perceptions of belongingness to the social environment, because changes in Relatedness did not extend to 4weeks post. Nevertheless, it is important to mention that the present study replicated the findings of Forstmann et al. (2020) using a prospective design and the same measure (i.e., Relatedness in the present study). Our results notably differed in demonstrating that the effect of enhanced connectedness with other human beings persisted for up to 2weeks (versus 24h demonstrated in their study).
Our findings may hold important clinical implications. Social disconnectedness is a common feature of internalizing and stress disorders (Karp, 2017; Kintzle et al., 2018), and connectedness is considered a core component of psychological well-being (Lee et al., 2008; Cervinka et al., 2012). Furthermore, social disconnectedness shows concurrent and longitudinal relations with loneliness (Jose and Lim, 2014; Ang, 2016). Accordingly, it will be important for future research to examine perceived social connectedness as a possible psychological mechanism underlying therapeutic psychedelic-induced effects on depression, stress, and loneliness.
Is Change in Personality Connected to Change in Perceived Social Connectedness?
Adaptive change in perceived social connectedness significantly covaried over time with a number of personality outcomes including neuroticism, extraversion, agreeableness, and conscientiousness. The present approach was not able to evaluate the causal directionality of these relations. Therefore, our results provide only preliminary data with regard to the processes underlying adaptive change. It will be important for future work to explore mechanistically how these change processes interact with each other (e.g., through the use of ecological momentary assessment). As one possibility, enhanced perceived social connectedness may lead to expanded in-group identification, lower distrust, reduced neuroticism, and enhanced extraversion, agreeableness, and conscientiousness. Alternatively, reduced neuroticism and enhanced extraversion and agreeableness may be primary and serve to amplify perceptions of social connectedness as individuals deepen their prosocial involvement in the social environment. Given the rapidity with which perceived social connectedness emerged in previous work (Forstmann et al., 2020), the latter explanation may be less likely as changes in social behavior may not have had significant time to unfold. As a further explanation, interindividual overlap between constructs may be suggestive that observations of covariation over time are merely artifacts of the overlapping component changing in both. We consider this possibility while recognizing that interindividual covariation does not necessarily imply intraindividual covariation over time (Molenaar, 2004; Fleeson, 2007). Our results indicated that interindividual overlap with perceived social connectedness in the cases of TIPI Critical and Disorganized was small (|r|<0.30), whereas overlap in the cases of TIPI Anxious and Extraverted was more substantial (|r|>0.30). This pattern is tentatively suggestive that intraindividual covariation is more likely to be suggestive of distinct constructs with common processes in the former cases, and common constructs in the latter. As a final comment on our results, only SCS Social Connectedness exhibited covarying relations with personality, suggesting that common processes may underlie change in perceived social belonging and personality, but not perceived relatedness to other human beings (Relatedness) and personality.9
Are There Factors That Predispose or Potentiate Change in Social Functioning-Related Traits and Perceived Social Connectedness?
Four-hundred-thirty-two analyses were conducted to examine the degree to which changes in outcomes were moderated by predisposing and acute factors, with eight significant results emerging (2% of analyses). Although this rate exceeds the Type I error rate expected from setting an alpha level of p<0.005 (i.e., 0.5%), the low number of significant results is suggestive that they should be cautiously interpreted as explorative findings warranting future replication. In general, predisposing and acute factors did not emerge within our general population data. Moreover, our hypotheses of moderated change in neuroticism, extraversion, and openness by mystical experience were not supported. Given that our sample was relatively well-powered to interpret a small interaction effect in most cases, it is important to consider why our null results differ so starkly from other studies that observed greater evidence of moderation (e.g., MacLean et al., 2011; Erritzoe et al., 2018; Weiss et al., 2021). One possibility is that use in the general population—lacking the control and introspective attentional buffers of psychedelic-assisted and ceremonial contexts—includes greater variability in other factors not measured here (e.g., relationship dynamics among participating users) that increase unsystematic variance in change trajectories. Another possibility is that the online volunteer format of survey response impacted the fidelity with which participants rated their experiences, though no evidence exists to this effect. A third possibility is that previous work has overstated the influence of predisposing and acute factors on psychedelic-induced personality change.