Sixteen spiritist centers were contacted, of which 5 allowed an oral presentation of the study on their premises; another 2 allowed the delivery of an invitation letter to the mediums, and those who were interested in participating contacted the first author by telephone, who carried out the clarification and consent procedures; the author also forwarded the screening instruments by e-mail. Out of a total of 70 mediums, 30 with a high frequency of hallucinatory experiences and participants in weekly mediumship meetings for more than two years were included in the main study; 6 were selected for qualitative analysis of the phenomenology of the hallucinatory experiences (Table 1).

Regarding the results of the clinical and neuropsychological evaluations, it was found that the 6 participants did not present cognitive deficits and did not meet diagnostic criteria for any mental disorder at the time of the interviews and testing (Table 1).

Regarding the analysis of the phenomenological interviews, two general categories were identified regarding the predictability of hallucinatory experiences [Trance (T) – hallucinatory experiences occurring during the mediumistic trance; Non-Trance (NT) – hallucinatory experiences occurring in daily life in a normal state of consciousness]. The predictability criterion was used because during the mediumistic sessions, in which the mediumistic trance is stimulated as a religious practice, the hallucinatory experiences were expected by the mediums, produced and encouraged given the nature of the mediumistic trance and the propitious religious environment; hallucinatory experiences that occurred in daily life had descriptions similar to those that occurred during mediumistic sessions and began without the medium’s knowledge, but were controlled by him/her, signaled through the medium’s awareness and mental procedures used to reduce or extinguish the hallucinatory experience. Within both categories, a subcategorization was made according to the sensory modality prevalent during the hallucinatory experience [kinesthetic (K), visual (V), olfactory (O), auditory (A)]. Figure 1 presents the proportions of each of the identified assessed categories.

A few examples of each of the categories assessed are shown below:

KT (Kinesthetic Trance): It’s very tiring, so I sweat a lot, it’s... Sometimes I feel like I have spasms, tremors, it’s... Sometimes I feel like I’m suffocating... very tiring; a very strong presence inside me and then I started to tremble, feel very cold; my head grew and grew, it felt like I had hydrocephalus.

NKT (Non-Kinesthetic Trance): I could feel the exact shape of the person, but I couldn’t define his features; I felt that another person was combing his hair with me; I still feel it today, as if someone was passing by, making a movement in the air.

VT (Visual Trance): I see the spirit that is using me as a medium; when I touch certain things or enter a place, the images appear in my head as real images; the pictures I see are as if they were two-dimensional. I’m just seeing it like this. Just witnessing them. It’s as if I were inside the image.

NVT (Non-Visual Trance): Since I was a child, I have seen and heard things that no one else could see or hear; at night, a painter would appear to me every night; there was a child holding the door... this child was not at all like us, because his finger had disappeared; There was only one light and I can’t see a similar light; It was there, it kissed me on the forehead and then it disappeared, it vanished in front of me.

OT (Olfactory Trance): It doesn’t come through the nose. It’s as if you could smell it all over your body.

NOT (Non-Olfactory Trance): I started to perceive a very strong sugar smell... for me that was concrete, I wasn’t thinking, I was imagining going through a mediumistic experience.

AT (Hearing Trance): Some spirits talk to me by moving their mouths like you are moving, others talk simply by looking in the direction of my eyes; I receive a voice message inside my head, from a spirit; I hear my voice when I am speaking, but it didn’t go through my brain.

NAT (non-hearing trance): Look, I heard parallel voices. Complete ones. Complete dialogues of people sometimes laughing; for me it is very natural to be talking to spirits; I hear someone calling me and there is no one calling me.

Despite the recent decades’ efforts of the scientific community to study the symptoms of psychosis and their presence in the healthy population, especially hallucinations, the technical-scientific scenario remains quite complex and many factors appear to contribute differently to the build-up of the phenomenon (Chinchani et al., 2021; Maijer et al., 2018). The aim of this study was to explore the phenomenology of hallucinatory experiences of mentally healthy mediums with a view to contributing to the understanding of the characteristics of non-pathological “psychotic experiences” in the non-clinical population. We found that the visual, auditory and olfactory sensory modalities were more frequent during daily life, similar to studies with non-clinical populations (Moseley et al., 2021; Toh et al., 2020), and are qualitatively similar to those that occur during mediumistic trance. In addition, the kinesthetic modality appeared with greater frequency and richness of detail during mediumistic trance.

In general, the frequency of mysticism and delusions of grandeur is high in psychotic patients, actually around 25% to 39% of patients with schizophrenia and 15% to 22% of patients with bipolar disorder (Loch et al., 2019). Individuals with religious delusions have more severe symptoms compared to other patients (Anderson-Schmidt et al., 2019). In our study, the six mediums did not present delusions or other psychotic experiences, which may be a determining factor as a possible explanation for the fact that the mediums reported controlled hallucinatory experiences (Loch et al., 2019; Menezes & Moreira-Almeida, 2010). Peters et al. (2016) confirm the idea of symptoms severity such as the insertion of thoughts into another person and mind reading as important factors in psychosis; however, among the mediums assessed, this effect did not occur, possibly due to the religious/spiritual framework (Milner et al., 2019). Schizophrenic patients tend to be more paranoid, with threatening appraisals (Milner et al., 2019); The hallucinatory experiences of mediums are interpreted according to the precepts of their religion, even when they occur during everyday life (Wahbeh & Butzer, 2020).

In another line of research, schizotypal traits have been investigated in clinical and nonclinical populations in relation to three basic factors of schizotypy: (1) anomalous cognitive and perceptual experiences (positive factor), (2) interpersonal deficits (negative factor), including physical or social anhedonia, and (3) cognitive or psychological disorganization (Kocsis-Bogar et al., 2013). Cluster analyses have indicated that there are two main groups that score high in schizotypy: one related to more mental health problems (‘high’ schizotypy: high scores on all three dimensions of schizotypy) and another more related to mental health, the so-called ‘happy schizotypal’ or ‘benign’ schizotypy (high scores only on the positive factor of schizotypy, linked to anomalous experiences such as hallucinations) (Farias et al., 2013; Harris et al., 2020). The results of these studies have indicated that the increased incidence of the three factors is associated with an increased likelihood that the person will develop some clinical disorder associated with psychotic disorders. Furthermore, it was found that suffering and incapacitation (signs of mental disorder) are positively correlated with the factors interpersonal deficits and psychological disorganization, while the factor anomalous cognitive and perceptual experiences are not correlated with mental disorders, but rather with spiritual/paranormal beliefs and practices among the non-clinical population (Alminhana et al., 2017a; Parra & Paulo, 2010). Other studies have investigated the psychological variables that could lead to the transition from subclinical to clinical expression, such as emotional stress (Cella et al., 2012; Collip et al., 2013; Scheunemann et al., 2019), adverse experiences in adolescence (Healy, Brannigan et al., 2019) and sense of self (Healy, Coughlan et al., 2019).

However, it is worth noting that there is still no consensus in the literature regarding the vulnerability factors that would trigger the transition to the pathological state (Salazar de Pablo et al., 2021; Salazar de Pablo et al., 2022). In recent years, a great deal of effort has been made to identify neurobiological markers that could help in understanding the risk state, thus enabling the identification of cases in which the transition to the pathological psychotic state could be more likely. However, there is a considerable lack of consistency in the literature due to methodological variations (patient recruitment, brain region of interest, method of analysis, and functional task employed) (Palaniyappan, 2019; Wood et al., 2013).

Finally, the group of mediums studied distinguishes hallucinatory experiences as not belonging to the reality of others, unlike the frequent descriptions among psychotic patients, in whom hallucinatory experiences break the threshold of contact with reality. This effect may be due to the fact that the mediums do not have cognitive deficits which are frequently present in psychotic patients. Another possible explanation for this effect in the case of the mediums assessed is the high level of education of the sample and lower consumption of substances, associated with lower levels of social adversity, these being protective factors in relation to the conversion to the psychopathological state (Coughlan et al., 2020).

The mediums we selected also reported intense participation in their religious community, enabling a social environment in which the anomalous experience would be associated with shared cultural factors and not with the disorder. It is important to emphasize the fact that Brazil is a country with high religious syncretism, which facilitates the creation of meanings regarding anomalous experiences associated with culture.

From a neurobiological point of view, some studies have indicated that the belief in the importance of Religiosity and Spirituality (R/S) would be associated with a thickening of some regions of the cerebral cortex, which also have the function of processing sensory information (bilateral parietal cortex and occipital regions) (Li et al., 2019). In a systematic review of the neurocorrelates associated with R/S, including 25 studies using methods such as electroencephalography, structural neuroimaging (MRI), and functional neuroimaging (fMRI, PET) and involving participants of different religions and R/S practices (e.g., resting state and prayer), the results indicate that, collectively, R/S experiences have specific neurobiological correlates and that these are recognizable, involving a number of different brain regions (Rim et al., 2019). Such evidence indicates a possible protective factor of R/S, which could explain the presence of psychotic experiences in the general population and the non-conversion to the psychopathological state.

Finally, more complex studies, involving not only behavioral variables, but also measurements of the brain function during hallucinatory experiences are necessary in order to develop more accurate explanatory hypotheses about the phenomenon of non-pathological hallucinatory experiences and their implications in the process of diagnosis and clinical intervention.