Mystical experiences occasioned by the hallucinogen psilocybin lead to increases in the personnality domain of openness, Katherine A. MacLean, Matthew W. Johnson and Roland R. Griffiths, 2011

Mystical experiences occasioned by the hallucinogen psilocybin lead to increases in the personnality domain of openness

Katherine A. MacLean, Matthew W. Johnson and Roland R. Griffiths

Journal of Psychopharmacology, 2011, 25, (11), 1453-1461.

doi: 10.1177/0269881111420188.



A large body of evidence, including longitudinal analyses of personality change, suggests that core personality traits are predominantly stable after age 30. To our knowledge, no study has demonstrated changes in personality in healthy adults after an experimentally manipulated discrete event. Intriguingly, double-blind controlled studies have shown that the classic hallucinogen psilocybin occasions personally and spiritually significant mystical experiences that predict longterm changes in behaviors, attitudes and values. In the present report we assessed the effect of psilocybin on changes in the five broad domains of personality – Neuroticism, Extroversion, Openness, Agreeableness, and Conscientiousness. Consistent with participant claims of hallucinogen-occasioned increases in aesthetic appreciation, imagination, and creativity, we found significant increases in Openness following a high-dose psilocybin session. In participants who had mystical experiences during their psilocybin session, Openness remained significantly higher than baseline more than one year after the session. The findings suggest a specific role for psilocybin and mystical-type experiences in adult personality change.

Keywords : hallucinogen; mystical experience; openness; personality; psilocybin; psychedelic



Psilocybin and other classic hallucinogens with actions mediated at the 5-HT2A receptor site (Glennon et al., 1984; Nichols, 2004) produce a unique profile of subjective effects including robust changes in perception, cognition, affect, volition, and somaesthesia (Isbell, 1959; Wolbach et al., 1962; Rosenberg et al., 1964). In early trials of hallucinogens administered under supportive conditions, 50 – 80% of participants claimed lasting beneficial changes in personality, values, attitudes and behavior (Metzner and Editors, 1963; McGlothlin and Arnold, 1971). Some of the most frequent subjective reports included greater appreciation of music, art and nature, greater tolerance of others, and increased creativity and imagination (McGlothlin et al., 1967). Consistent with these findings, Studerus et al. (2010) recently reported that nearly 40% of participants in several laboratory studies of psilocybin claimed positive long-term changes in aesthetic experience and in their relationship with the environment (i.e., nature) following their psilocybin sessions.

The long-term positive impact of hallucinogens may depend on their ability to occasion profound insights and mystical-type experiences (Pahnke, 1963; Doblin, 1991). The core features of mystical experience, as defined by Stace (1960) and Hood (2003), are feelings of unity and interconnectedness with all people and things, a sense of sacredness, feelings of peace and joy, a sense of transcending normal time and space, ineffability, and an intuitive belief that the experience is a source of objective truth about the nature of reality. Because such experiences appear to enable individuals to transcend their usual patterns of thinking, feeling, and acting, it is plausible that they could occasion changes in core dimensions of personality. In support of this, a double-blind controlled study by Griffiths et al. (Griffiths et al., 2006; Griffiths et al., 2008) demonstrated that a single psilocybin session occasioned
mystical experiences associated with positive changes in behaviors, attitudes and values more than a year later. Moreover, independent ratings from participants’ romantic partners, coworkers, and friends corroborated the first-person reports. These findings suggest fundamental changes in personal concerns, goals, and identity, which are considered to be important dimensions of personality (e.g., in the framework described in McAdams, 1995). However, the impact of psilocybin-occasioned mystical experience on core personality traits is unknown.

There is general agreement that personality traits are relatively enduring styles of thinking, feeling, and acting (McCrae and Costa, 1997). The most widely accepted model of personality structure is the five-factor model, which describes five broad domains of personality each encompassing many related traits: Neuroticism, Extroversion, Openness, Agreeableness and Conscientiousness (Digman, 1990; McCrae, 2009). Many studies have confirmed that these personality factors are heritable (Bouchard et al., 1990) and reliable across cultures, suggesting a universal human personality structure that is rooted in biology
(McCrae and Costa, 1997). Longitudinal studies have shown that individual personality is predominantly stable across the lifespan. Although there are mean-level personality changes after age 30, these shifts are typically gradual and subtle (1 – 2 T-score points per decade; Terracciano et al., 2005).

Despite the relatively stable nature of personality, researchers have hypothesized that significant life events could change adult personality quite dramatically. Studies investigating individual differences in personality-trait change have found that certain life experiences are associated with changes in adult personality (see review in Roberts and Mroczek, 2008). For example, personality changes have been associated with divorce (e.g., increases in Extroversion and Openness in women, Costa et al., 2000), remarriage (e.g., decreases in Neuroticism in men, Mroczek and Spiro, 2003), and career success (e.g., decreases in Conscientiousness in individuals who were fired vs. promoted, Costa et al., 2000). However, such correlational studies cannot address the causal link between particular events and subsequent personality change.

Relatively little research has investigated personality change in the laboratory, likely because events that might be expected to change personality are difficult to create under experimental (i.e., randomized or assigned) conditions. Some studies have shown changes in personality after experimental treatment interventions in patients, such as several weeks of antidepressant medication (e.g., Costa et al., 2005) and intensive outpatient counseling for substance abuse rehabilitation (Piedmont, 2001). Personality changes have also been shown in healthy adults after three months of intensive contemplative training in attention and emotion regulation (Sahdra et al., 2011). These personality changes, as well as socio-emotional and behavioral improvements, were maintained several months after completion of training, suggesting possible long-term benefits.

To our knowledge, no study has prospectively demonstrated personality change in healthy adults after an experimentally manipulated discrete event. Although it has been speculated that treatment with classic hallucinogens could be a method for occasioning dramatic and rapid personality change (Unger, 1964), a controlled study of LSD in healthy volunteers failed to find significant changes in a large battery of empirical measures of personality, aesthetic sensitivity, and creativity six months after LSD sessions (McGlothlin et al., 1967). Nevertheless, these investigators confirmed the subjective claims of long-term change frequently reported in uncontrolled trials.

The subjective claims of hallucinogen-occasioned long-term changes (Metzner and Editors, 1963; McGlothlin et al., 1967; McGlothlin and Arnold, 1971; Studerus et al., 2010) appear to align with the personality construct of Openness, which encompasses aesthetic appreciation and sensitivity, imagination and fantasy, and broad-minded tolerance of others’ viewpoints and values. The present report combines data from two double-blind controlled studies of psilocybin (Griffiths et al., 2006; Griffiths et al., 2011) to analyze changes in Openness and the other four broad personality domains using the NEO Personality Inventory (Costa and McCrae, 1992). Personality change was assessed 1 – 2 months after a high-dose psilocybin session and again more than one year later to determine the persistence of personality change. Consistent with previous results indicating a correlation between mystical experiences during the session and long-term spiritual significance and personal meaning attribution (Griffiths et al., 2008), we hypothesized that mystical experiences during the psilocybin session would lead to enduring increases in Openness.