The current study adds to the scientific literature by showing both sex-specific and more universal associations between cannabis use and several social psychological constructs associated with the concept of prosociality. Many of the constructs showed a linear relation with the recency of the last time the participants consumed cannabis, suggesting an immediate effect that diminishes over time. The general effect is consistent with a shift in perceptions that prioritize the role of prosocial behaviors, social empathy, benevolence, and fairness, independent of in-group identifications. In men, cannabis exposure was also associated with higher scores on the agreeableness personality dimension, matching levels of non-using females. The exception to this general shift towards heightened trait-levels of prosociality was the finding of higher aggression scores among female cannabis users, as compared to non-users. However, because the aggression scores were uncorrelated with recency of usage, they are likely the result of selection effects, whereby females that experiment with cannabis are more likely to score higher on trait aggression, on average, as compared to females that choose not to experiment with cannabis, rather than, for example, the possibility that cannabis directly increases aggressive behaviors in women²¹.

Our results are instead consistent with research showing the acute THC intoxication is usually associated with dampened aggression, and positively related to subjective feelings of openness, peace, joy, wonder, spirituality, and a heightened sense of connection to the universe^{22,28,33,51,52}, with some researchers estimating that frequent cannabis use can increase an individual’s sociability by as much as 68.4%, thinking profoundly by 31.4%, happiness by 16.1%, feeling nice or pleasant by 20.9%, insight into others by 11.9%, and insight into oneself or personal growth by 8.7%²². Similar findings show cannabis users report a greater ability to empathize with others when shown discrete facial expressions of emotion, as compared to non-users⁴¹. Still, cannabis’ effects on aggressive behaviors are likely moderated by a host of genotypic (e.g., HTR2B variation⁵³;) and circumstantial factors, including individual differences in baseline and diurnal mental and physical health states, recent and past experiences, social contextual and nonsocial environmental factors, and the natural heterogeneity of the Cannabis plant in and of itself.

The biopsychosocial mechanisms by which cannabis induces a transformation in perceptual functioning have not yet been the subject of full direct investigation, but can be interpreted in the context of broad behavioral and neurocognitive frameworks of affective behaviors and emotionality. From an ethological perspective, trustworthiness cues, or submissive affective displays are the types of behaviors that humans express in order to strengthen the intimacy and reliability of their relationships³. Cannabis usage may, therefore, induce the expression of communicative gestures, such as self-described and demonstrated empathy, in ways that effectively increase users’ social desirability and the overall reliability of their social spheres in ways that promote a state of psychosocial homeostasis³. The ability to appreciate another person’s suffering is an integral component of prosociality, and greatly increases the likelihood that people will engage in actual acts of beneficence^54–56. Another core component of prosociality, moral identity, outlines the individual’s sense of rightfulness and wrongfulness, and therefore, encourages and promotes what the individual considers prosocial behaviors and discourages antisocial behaviors^57,58. Many researchers believe that morality becomes ingrained during adolescence^59–63, and further research is needed to better understand how cannabis exposure at different stages throughout development may affect short-term and/or long-term changes in social psychological functioning.

Pharmacologically, consumption of the cannabis plant evokes feelings of well-being via activation of the endocannabinoid system, which helps regulate stress responses and reward motivations⁶⁴. One of the most commonly studied endocannabinoids is called anandamide, which means ‘supreme joy’ in classical languages⁶⁵, and in clinical samples, aggressive tendencies are associated with low basal levels of this naturally occurring endocannabinoid, suggesting a link between endocannabinoid deficiencies and aggression³³. Cannabis users have also been shown to produce reduced amygdala reactivity to threatening social stimuli³⁹, and cannabis usage rapidly amplifies one’s sense of happiness, optimism, and well-being⁶⁶, with large national databases showing the most frequently perceived side-effects of medical cannabis usage, recorded in real-time, are a heightened sense of feeling “relaxed”, “peaceful”, and “comfy”²⁸. These findings are in direct contrast to findings from other intoxicants, such as alcohol, that are well-established to cause acute increases in hostility and aggression²⁶.

Nonetheless, the current study is not without limitations. Our cross-sectional analyses do not enable us to track participants over time, in particular, pre- and post-cannabis use, preventing an analysis of the within-user effects of cannabis on our social construct measures. Likewise, the convenience sample of university, undergraduate, psychology students included is fairly small (146 individuals) and may not be representative of the wider community, thus limiting the generalizability of our findings. For example, college students often differ from non-students in basic demographic characteristics (e.g., age, SES, health status), as well as how individuals encounter and are informed about the usage and effects of cannabis. It is possible, for example, that non-college students may have cannabis-related experiences coupled with harsher life circumstances and less positive events, rendering differential effects of cannabis use based on psychologically-conditioned responses. However, the university from which the current sample was recruited is designated as a “majority-minority” institution, with ethnic and racial compositions similar to the wider region, and includes a large proportion of “non-traditional” students (e.g., lower SES than national averages). Thus, the study’s limitations should be weighed against its unique strengths of being able to contrast (pre-COVID) normative psychological functioning among a relatively homogenous sample of healthy, young adults.

In conclusion, this is among the first studies to demonstrate a direct association between non-medical cannabis use and positive psychological outcomes in otherwise healthy young adults. Studies have shown that people develop their personalities during adolescence and young adulthood^1,67–69, when prosocial behaviors and habits are also formed^70,71, rendering the need for further basic psychological research in these age groups, especially among cannabis consumers outside of our sample, such as those with physical or mental health disorders. For example, if regular consumption of the Cannabis plant promotes prosociality, this raises the possibility of its use as an adjunctive therapy, e.g., among people being treated for ‘conduct disorders,’ such as the majority of incarcerated individuals in the U.S. Or, perhaps, cannabis may simply prove useful among people seeking to incorporate a heightened sense of prosociality in their daily activities and psychological perspectives. Of course, the benefits of any such use should be carefully weighed against potential costs to health and financial wellbeing.