Studies
A lot of skeptics will say "I won't believe that this is real until you show me studies about it." Well, here are the studies.
Keep in mind that some of these may be outdated or biased, or run off of small surveys and sample sizes. Please consume these articles with an open mind and a grain of salt. Also note that this list does not include as many studies on traumagenic and dissociative plurality, as those studies are plentiful and easy to find compared to studies about general or endogenic plurality.
This page is still a work in progress. Big thanks to Wolfgang for compiling the list so far.
Studies - https://old.reddit.com/r/Tulpas/wiki/studies
Young people's narratives of hearing voices: Systemic influences and conceptual challenges - https://onlinelibrary.wiley.com/doi/full/10.1002/cpp.2532
Can the DSM-5differentiate between nonpathological possession and dissociative identity disorder? A case study from an Afro-Brazilian religion - https://www.psychologytoday.com/sites/default/files/Possession%20and%20DSM%205.pdf
Tulpas and Mental Health: A Study of Non-Traumagenic Plural Experiences - http://pubs.sciepub.com/rpbs/5/2/1/index.html
Varieties of Tulpa Experiences: Sentient Imaginary Friends, Embodied Joint Attention, and Hypnotic Sociality in a Wired World - http://somatosphere.net/2015/varieties-of-tulpa-experiences-sentient-imaginary-friends-embodied-joint-attention-and-hypnotic-sociality-in-a-wired-world.html/
What we can learn about respect and identity from ‘plurals’ - https://aeon.co/ideas/what-we-can-learn-about-respect-and-identity-from-plurals
Non-Traumagenic or Non-Disordered Multiplicity - a collection of studies on the matter https://docs.google.com/document/d/1-NcaRVzSattTIEfy9GEViZWVLNbHpB2THwaSYdPi98o/edit?usp=sharing
Claims There Is No Research On Endogenics - same as the link above https://kinhost.org/Main/ClaimsThereIsNoResearchOnEndogenics
Multiplicity: An Explorative Interview Study on Personal Experiences of People with Multiple Selves - (Study done by an abusive hypnotist, kicked from community soon after publishing study, poor methodology) -https://www.frontiersin.org/articles/10.3389/fpsyg.2017.00938/full / https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5468408/