San Pedro, a mescaline containing cactus, has been used for thousands of years and is currently popular as a psychedelic substance in ceremonial retreats in Europe. The current research investigates the consciousness altering effects of San Pedro. Forty-two participants who joined ceremonial psychedelic retreats in the Netherlands were investigated with questionnaires probing 11 dimensions of altered states of consciousness (11D-ASC), ego-dissolution, mystical experiences, and challenging experiences. Results tentatively demonstrate the status of San Pedro as a psychedelic, revealing deviations from normal waking consciousness on all 11 subscales of the 11D-ASC, moderate scores of ego-dissolution, and a complete mystical experience in two thirds of the participants. Furthermore, a consciousness profile of San Pedro was constructed, which revealed that spiritual experiences are strongly expressed in ceremonial San Pedro use. Furthermore, the San Pedro experience is characterized by low levels of disembodiment, anxiety, impaired control and cognition, transcendence of space, and relatively higher levels of physical distress and grief in case of (incidental) challenging experiences. Finally, graph network analysis indicated two separate networks of positive and negative altered states of consciousness. Possible interpretations of these findings are discussed in relation to the ceremonial setting, sympathomimetic effects of San Pedro's alkaloids and variations in affective valence.San Pedro, Huachuma, or Echinopsis pachanoi is a psychoactive psychedelic plant from the family of Cactaceae. Native to the South American Andes, San Pedro has a long history of being harvested by indigenous societies, to be consumed as a medical plant sacrament during ceremonial rituals (Jay, 2019). Anno 2022, ceremonial San Pedro use has spread to western countries, where local ceremony providers offer San Pedro to participants for its healing potential, among other reasons (Uthaug, Davis et al., 2021). From research with other psychedelic drugs, we know that the altered states of consciousness generated by psychedelics offer a growing range of therapeutic applications (Garcia-Romeu et al., 2016), as well as psychological risks (Carbonaro et al., 2016). However, to this date, no research has exclusively investigated the psychological effects of ceremonial San Pedro use. In order to fill this hiatus in the literature and to aid the development of psychedelic assisted therapies, the current

Objectives The current study assessed whether trait mindfulness relates to social decision making as increased acceptance rates towards offers in the Ultimatum Game. Mindfulness has been associated to a reduction in emotional reactivity and an increase in emotion regulation once intense emotions do occur. Therefore, we reasoned that trait mindfulness would predict acceptance in the Ultimatum Game, perhaps even in case of unfair offers. Methods In two online studies we assessed whether trait mindfulness positively predicts acceptance of offers in the Ultimatum Game among community samples (study 1 N = 107; study 2 N = 118). In study 2, we also assessed participants’ emotional reactions to offers prior to their decision to accept or reject. Results Whereas study 1 indeed showed a significant positive relation between trait mindfulness and acceptance of offers (OR = 2.01, p = .05), study 2 did not show this relation (OR = .91, p = .81). Also, the results of study 2 showed that trait mindfulness may moderate emotional responses to offers (β =  − .06, p = .03). Yet, analyses of the pooled data indicated no relation between trait mindfulness and acceptance of offers (p < .15). Conclusions Our research provides mixed support regarding the association between trait mindfulness and behavioral acceptance of offers in the Ultimatum Game. We discuss the need for more fine-grained examinations of when and why mindfulness should lead to acceptance of unfairness, and if and when mindfulness would lead to wise responding in social exchange situations.