Couple of questions above that I may be able to shed some light on. There have indeed been studies that have electrically stimulated the fusiform face area and other related brain regions in patient populations. I'll attach two relatively recent papers - one that involves direct electrical stimulation of the fusiform face and related areas with implanted electrodes, and another relevant paper by that involved stimulation of the parahippocampal place area and the temporal lobe. Both kinds of stimulations invoked rather mundane visual phenomena, with subjects seeing faces and scenes very obviously derived from personal memories. For example, in the fusiform study, the subject reported seeing the doctor's face "morph" into the face of that of a different person, who apparently "looked familiar". In the second study that stimulated the parahippocampal place area, the subject reported "dream-like" imagery and seeing scenes from her neighborhood (houses, etc), as well as familiar (human) faces. (I personally see a strong dissimilarity in these kinds of studies and the phenomenology of psychedelics, with any possible overlaps being rather superficial. But you're free to judge for your self.)
EDIT: Forgot to attach a paper that reviewed the effects of applying transcranial magnetic stimulation to the fusiform face area. It was noted that TMS application to fusiform area interfered with patients' ability to discern emotional content of faces and to discriminate faces from objects, but that these effects were dependent on a larger network of cortical regions [Atkinson, A. P. and Adolphs, R. (2011). The neuropsychology of face perception: beyond simple dissociations and functional selectivity. Philosophical Transactions of the Royal Society].
Regarding reports of naive subjects and their experiences with psychedelics: This can be a complicated and tricky question, but there's some avenues that have been explored already. It definitely would be illuminating to see more research of the kind described below, however.
Take groups of people who have never seen (in real life) certain themes commonly reported by standard western psychonauts (such as the prototypical grey alien face, ancient egypt iconography, jesters, and so on) and give them DMT.
For example uncontacted indigenous tribes who are completely removed from global civilization.
Give them DMT in a controlled setting and see what kind of visions they report.
- Beginning in the late 1960's, Claudio Naranjo studied the effects of harmaline (ayahuasca brew component) in ostensibly naive subjects who were born/raised in urban environments, an who were supposedly unaware of the lore associated with Amazonian shamanism. A few papers were published on this research: Among other things, the so-called "urban elite" subjects did report seeing visions of snakes and jaguars, as well as various imagery germane to the ayahuasca literature.
- As Obliguhl stated above, Benny Shanon's "Antipodes of the Mind" is a cognitive-psychological investigation into this very question, i.e. that of highly specific cross-personal semantic similarities in the imagery of subjects participating in ayahuasca ceremonies. (Shanon himself claims to have been naive to the subjective properties of ayahuasca the first few times he imbibed, and in "Antipodes" he collects and analyzes the reports of numerous other individuals, many of whom were also similarly naive). "Antipodes of the Mind" is a truly extraordinary piece of investigative work on the phenomenological properties of ayahuasca - really second to none thus far - and I couldn't recommend this book more.
- In an essay by researchers David Luke and Andrew Gallimore that was included in "Neurotransmissions" (collection of essays derived from the Breaking Convention conferences), the authors reviewed a 1950s study by Hungarian physician and chemist Stephan Szara, in which Szara administered DMT to schizophrenic patients in an attempt to explore a 5-HT2A model of psychosis. The paper by Luke and Gallimore compares the reports of these 1950s patients with more contemporary reports. While the reports of Szara's patients are rather sparse, there are some striking similarities that can be noted.
- Rick Strassman states in "DMT: The Spirit Molecule" that he was wary of a potential "McKenna effect" - that is, that Terence McKenna's rap about DMT entities could have subconsciously influenced the trip of his subjects. Strassman states (in note 1 of chapter 21) that he queried his subjects on whether or not they were familiar with Terence McKenna's now infamous spiel (or, for that matter, if they were previously aware of any reports of encounters with entities characteristic of the DMT-trance). "Few if any were," he states therein, and concluded that the "McKenna effect" couldn't account for the majority of his subjects' reports.
There's a number of other reports scattered in the published literature of (in my opinion) credible researchers who claim to have been naive at the time that they imbibed various psychedelic substances, but I'll leave it at that for now unless anyone asks. (I know, for example, both David Luke and Andrew Gallimore have published separate papers on this issue). I'll attach the paper by Luke and Gallimore, as well as a paper by Shanon that briefly gives an overview of "Antipodes of the Mind". Also below are citations for the aforementioned Naranjo studies.
Naranjo, C. (1967). Psychotropic properties of the harmala alkaloids. In D. Efron (Ed.),
Ethnopharmacologic Search for Psychoactive Drugs: Proceedings of Symposium held in San Francisco, January 28-30, 1967 (pp. 385-391). Public Health Service Publication No 1645. Washington, DC: US Department of Health, Education, and Welfare.
Naranjo, C. (1973). The healing journey: New approaches to consciousness. New York: Ballantine Books.
Naranjo, C. (1987). “Ayahuasca” imagery and the therapeutic property of the harmala alkaloids. Journal of Mental Imagery, 11 (2), 131-136.