The persistence of the subjective in neuropsychopharmacology: observations of contemporary hallucinogen research

Langlitz opens by situating contemporary hallucinogen research at the intersection of neuroscience and questions about the status of subjective experience. The paper contrasts eliminative materialist claims—that neuroscientific accounts render subjective reports illusory—with the empirical practices of psychopharmacology, arguing that subjective experience remains a persistent epistemic object rather than being simply eradicated by brain imaging and neurochemistry. Ethnographic vignettes from the laboratories of prominent researchers are used to frame a philosophical puzzle: how do first-person reports and neurophysiological measurements relate when both are invoked to study altered states induced by substances such as psilocybin and ketamine? The study sets out to explore how subjectivity figures in laboratory practice rather than to test a causal hypothesis. Through ethnographic observation and interviews in European psychopharmacology labs, Langlitz examines three domains in which subjectivity persists: as data (introspective self-reports used alongside neuroimaging), as the personal experience of scientists themselves, and as a culturally mediated form of experience that shapes both experimental outcomes and researchers' self-conceptions. The paper treats hallucinogen research as a case study to illuminate broader tensions between objectivist ideals and the lived practices of cognitive neuroscience.

Langlitz employs an ethnographic case-study approach focused on contemporary hallucinogen research in Euro-American laboratories. The analysis is based on fieldwork and interviews with researchers and administrators, participant observation of laboratory routines and pilot trials, and examination of laboratory documents such as participant protocols and the use of psychometric instruments. The extracted text does not clearly report the total number of interviews or the precise duration of fieldwork in the body of the Introduction and main sections. Data sources described in the paper include firsthand experience reports from test subjects (protocols reproduced in the lab), conversations with researchers in laboratories in Switzerland and neighbouring Germany, and detailed reconstructions of specific incidents (for example, a pilot EEG trial that went awry). Langlitz reads these ethnographic materials alongside methodological practices in psychopharmacology—use of PET, EEG, neuropsychological tests, and standardised self-rating scales—treating practices such as self-experimentation, pilot trials, and the deployment of questionnaires as ethnographic evidence of how subjectivity is handled in the laboratory. The analytic strategy is interpretive and comparative, drawing on concepts from the history and philosophy of science (objectivity, trained judgement, human kinds) to make sense of the observed practices.

Langlitz presents several interrelated empirical findings about how subjectivity persists in neuropsychopharmacological practice. First, subjective reports remain central as scientific data: neuroimaging studies in the labs examined routinely pair PET or EEG measurements with standardised introspective instruments such as Dittrich's APZ questionnaire, a 94-item scale that operationalises three dimensions of altered states of consciousness ('oceanic boundlessness', 'dread of ego-dissolution', and 'visionary restructuralization'). These self-ratings are statistically correlated with spatially differentiated metabolic measures (the lab used Spearman correlation coefficients) to establish neural correlates of drug-induced phenomenology. Langlitz notes a methodological tension: researchers treat imaging as measurement of numbers rather than mere pictures, yet those numeric mappings remain fundamentally dependent on first-person reports because without them measured signals cannot be interpreted as correlates of particular conscious states. Langlitz also highlights a practical difficulty: participants often report that questionnaires inadequately capture singular, in-the-moment experiences and that retrospective ratings can miss features that escape objectification during the altered state. Second, personal familiarity with the drugs matters in practice. Field evidence includes debates over researcher self-experimentation (for example, a dispute between a Swiss laboratory head and a public-health administrator about whether the study director should serve as a subject), and pilot studies in which junior researchers tried the drugs themselves to test procedures. One vignette describes a pilot EEG trial in which an investigator became highly distressed under psilocybin, prompting adjustments to the experimental environment (redecorating the EEG chamber, replacing neutral images with more positive stimuli) and the intervention of a senior researcher who drew on prior personal familiarity to calm the subject. Langlitz argues that such firsthand experience produces forms of practical wisdom and empathy that are valuable for participant care and for interpreting ambiguous performance data—cases in which subjects are absorbed in subjective phenomena and perform poorly on cognitive tests not necessarily because of cognitive impairment but because they are engrossed in the experience. Third, researchers' own drug experiences feed back into their self-conceptions and theoretical commitments. Interviews and quotations from laboratory scientists indicate that many came to think of themselves as 'neurochemical selves' after experiencing how small pharmacological interventions can reorganise perception, emotion and sense of self. Langlitz frames this as a looping effect: scientific categories and researchers' experiences mutually shape each other, making the psychedelic experience a 'human kind' in Ian Hacking's sense rather than a simple natural kind. Finally, the paper documents that although earlier proposals—such as Anthony Wallace's idea of 'cultural and situational controls' to systematically vary setting while holding drug dose constant—have been suggested historically, such approaches have not been widely integrated into contemporary psychopharmacological practice, which continues to privilege placebo-controlled trials and strategies that aim to isolate pharmacological effects.

Langlitz interprets these findings as evidence that subjectivity persists in contemporary neuropsychopharmacology on multiple levels despite the discipline's objectivist rhetoric. The paper emphasises that introspection has been rehabilitated alongside neuroimaging because investigations of consciousness require first-person reports to give neural data their interpretive referent. At the same time, researchers' personal experiences with hallucinogens contribute to experimental design, participant care, and the epistemic judgements used to interpret ambiguous results; this trained judgement reintegrates a form of subjectivity into scientific practice. The author stresses that these dynamics complicate simple eliminativist positions that claim neuroscience renders subjective experience obsolete. Relative to earlier work, Langlitz situates contemporary laboratory practice as neither purely natural-scientific nor purely human-scientific: hallucinogen research straddles both domains and thereby exposes limits of standard pharmacological designs in accounting for cultural and situational determinants of experience. The paper acknowledges key uncertainties and limitations: it is an ethnographic case study whose conclusions are not directly generalisable, and many relevant details (for example, how widely Wallace-style cultural controls might be implemented or quantified) remain unresolved within the presented material. Langlitz argues for methodological pluralism, proposing that investigations of psychedelic phenomena would benefit from interdisciplinary 'experiments in interdisciplinarity' that incorporate anthropological and other human-science approaches to study set and setting systematically. The discussion closes by posing open questions the author considers important for future work, including how strongly cultural determinants shape hallucinogen effects and whether non-pharmacological factors similarly modulate other classes of psychoactive drugs.

Langlitz concludes that subjectivity endures in psychopharmacology both as necessary data for correlating brain activity with conscious states and as a constitutive element of experimental practice through researchers' own experiences. The paper recommends that the psychedelic experience be recognised as a human kind shaped by cultural and situational factors and that psychopharmacology consider supplementing placebo-controlled designs with methods capable of interrogating those factors. Finally, the author calls for careful interdisciplinary work at the borderland of the human and natural sciences to determine how far and in what ways set and setting mould drug effects, and whether such non-pharmacological influences extend beyond hallucinogens to other psychoactive agents.