Authors : Anne Harrington (1)
1- Harvard University
Lourdes is a town in southern France, in the foothills of the Pyrenees mountains, not far from the Spanish border. It is also one of the most famous pilgrimage sites in Catholicism, because (as we all know) it is where miracle healings happen. Fewer of us know that, on the grounds of the Lourdes Sanctuary is a dull-looking office known as the Lourdes Medical Bureau, whose task it is to assess all claims of extraordinary healings brought to its office, and decide which among these are in fact completely inexplicable. Because of its work, the Bureau contains an archive with dossiers on every single case that has been brought to the attention of its doctors – some 8,000 or so.
Most researchers interested in the medical archive at Lourdes have focused on the very small number of alleged true miracles documented in that archive (a mere 72 to date). In this talk, though, I will argue that the tendency to see Lourdes as an archive of “miracles” misses the even more profound lessons to be learned from the thousands and thousands of “almost miracles” or “failed miracles” also documented in this archive. These “other cases” collectively offer a vast and varied repository of extraordinary human experiences that we can take seriously while side-stepping questions of theology. At the same time, simply employing concepts like “placebo effect,” “suggestion,” and “psychosomatics” is unlikely to take us where we need to go. We need instead to develop frameworks and vocabularies that will allow us to ask questions about the therapeutic architecture of a healing experience: an architecture marked by rhythms of despair and hope, travel and arrival, ritual and normalcy, isolation and immersive community, liminality and return. In other words, Lourdes as a site of human experience (rather than theological demonstration) shows us that, if we want to do fuller justice to the cases of unexplained healing that interest all of us at this conference, we need to become even more radically interdisciplinary than we perhaps had realized.
Authors : Quinton Deeley (1)
1- King’s College London
The cortical hierarchy provides an anatomical basis for differing neurocognitive and computational theories applied to suggested effects, placebo, and functional symptoms – hierarchical predictive coding, top down cortical feedback and signal routing, and attractor dynamics. Each theory views the brain as a graded anatomical hierarchy with bidirectional influences between levels. Each considers that representations privileged by heightened attention (whether by cognitive control or automatic processes) alter the pre-conscious “editing” of experience to generate suggested and placebo effects and functional symptoms. This occurs through an increase in top down signals relative to bottom up signals across the cortical hierarchy, resulting in enhanced activation of selected neuronal populations in intermediate levels. This alters the interpretation of bottom up signals or radically misrepresents the presence or absence of bottom up signals to higher levels. By contrast VR influences experience by simulating the bottom up effects of veridical sensory input to sensory processing streams. Despite the shared framework of the cortical hierarchy the theories differ in important respects. Implications for future research and combining suggestion, placebo and VR to treat functional symptoms are considered.
Authors : Madeline Stein (1); Jason Helstrip (2); Benjamin Parris (2); Devin Terhune (1)
1- Department of Psychology, Institute of Psychiatry, Psychology & Neuroscience, King’s College London (United Kingdom)
2- Department of Psychology, University of Bournemouth (United Kingdom)
The term ‘suggestion’ is frequently used in a wide variety of clinical and research domains spanning law, medicine, psychiatry, and psychology. However, the term is often undefined, poorly defined, or used inconsistently, leading to ambiguity in its usage across theoretical, empirical, and clinical domains. This presentation will review the results of a pre-registered, three-round modified Delphi study recruiting international experts from the fields of hypnosis, placebo/nocebo responding, and forensic/memory research to establish a consensus definition of suggestion. Exploratory questions were used to characterise experts’ perspectives on within- and between-context stability of responsiveness to suggestion (i.e., suggestibility). Thirty-nine expert panellists participated, and 94% completed all three rounds. Panellists reached moderate consensus (75.6% agreement) on a definition of suggestion. There was no consensus on the temporal stability of suggestibility (44% agreement), on whether hypnotic, placebo/nocebo, and forensic contexts share an underlying domain of suggestion (37% agreement), and views on preferred terminology for suggestibility were heterogeneous.
The establishment of a consensus definition of the term suggestion provides a foundation for improved cross-domain communication and theory development and enables novel directions for basic and applied research.
Authors : Devin Terhune (1)
1- King’s College London
Across disciplines, suggestions are typically conceptualised in a monolithic manner with little consideration of their component features. This has hindered experimental research and clinical applications, including comparisons of suggestion effects across domains and efforts to standardise or optimize suggestions. Many of these limitations arise from the absence of a framework that decomposes suggestions into their constituent dimensions. Here I will introduce the dimensional model of suggestion (DIMMS), which characterises suggestion effects across three layers: (i) a structural layer of dimensions capturing component features of suggestions (e.g., magnitude, locus of attribution), (ii) a contextual weighting layer comprising environmental and interpersonal factors that modulate how structural dimensions are weighted and expressed, and (iii) a representational layer corresponding to a potentially reduced multidimensional representational state. By specifying this architecture, DIMMS provides a foundation for quantifying, comparing, and systematically manipulating suggestions across contexts. I will conclude by outlining its implications for hypnosis, placebo, and functional neurological disorder.
Authors : Nathan Eulry (1); Renaud Evrard (1)
1- Laboratoire de psychologie de l’interaction et des relations intersubjectives Université de Lorraine
Exceptional experiences generally occur spontaneously. However, certain methods seem able to provoke similar experiences. In 1990, Canadian researchers used weak electromagnetic microfields applied to the temporal lobes via a helmet (nicknamed “God helmet”) and reported “unusual perceptions,” such as ethereal presences, in 80% of participants (Ruttan et al., 1990). Later replication attempts showed that the experimental context and participants’ expectations play a decisive role in the occurrence of such experiences (Granqvist et al., 2005; Irwin et al., 2013; Simmonds-Moore et al., 2019). The difficulty of obtaining precise information on how the helmet works, as well as the lack of communication from the Laurentian University team, led researchers to use placebo devices that recreate the experimental context without electromagnetic stimulation, allowing them to focus on general induction factors that may be common to all induction devices.
Thirty-five years later, we revisit this line of research in order to reassess the actual importance of suggestion (neuro-placebo) in the induction of exceptional experiences. The CEREBRO study (Contextual Effects and Real Effects in Brain Responses Optimization) hypothesizes that a favorable context increases the likelihood of an exceptional experience. Moreover, certain personality traits that have not yet been explored in replications of the God helmet could influence the emergence of such experiences. To assess these traits, we administered several questionnaires: the French Phenomenology of Exceptional Experiences Revised-2 (Fr-PAGE-R-II), the Dimensions of Religiosity Scale (Joseph & DiDuca, 2007), the Dissociative Experiences Scale (Carlson & Putnam, 1993), the Brief Suggestibility Scale (Wieder & Terhune, 2019), and the Mental Health Inventory-5 (Berwick et al., 1991).
A total of 106 participants spent 40 minutes in a sensory-deprivation booth wearing a fake God helmet. Two experimental conditions were created. In the first, participants were told that the experiment concerned the impact of electromagnetic fields on thought and imagination. In the second, they were informed that the setup was designed to induce strange experiences using micro-electromagnetic fields. In both cases, the setup was strictly identical and the helmet was non-functional. Participants were told that there was a 50/50 chance that the helmet was either switched on or off, determined randomly, and were debriefed at the end of the session that the helmet was entirely a placebo. Thus, the only difference between the two experimental groups lay in how the device was presented. This design enables us to assess the impact of context on the likelihood of having an exceptional experience— that is, to determine whether simply telling a participant that they might have such an experience is sufficient to elicit it. After spending 40 minutes in the sensory-isolation booth, participants were asked to describe their experience using a questionnaire assessing altered states of consciousness (Studerus et al., 2010), followed by an interview with the experimenter using the micro-phenomenological method to obtain a detailed account of their experience (Petitmengin et al., 2017; Zapata, 2022). We reserve the presentation of our first results for this conference.
Authors : Matthew Cohen (1); Quinton Deeley (1); Devin Terhune (1); Mitul Mehta (2)
1- King’s College London (United Kingdom)
2- Institute of Psychiatry, Psychology & Neuroscience, King’s College London (United Kingdom)
Introduction: Mystical-type-experiences (MTE) have been posited to mediate clinical response to psychedelic-assisted therapy (PAT), yet they are not universal across psychedelic phenomena. Experiences with agents (EWA) have been emphasised in ritual use of hallucinogens in non-western contexts. It is unknown whether differences in psychedelic experience are driven by pharmacology or cultural expectations.
Previous studies have observed that non-specific psychedelic-like phenomena can be simulated with placebo, and that MTE can be elicited with verbal suggestion. No prior studies have combined methodologies, or explored if suggestion can elicit EWA.
Aims: To investigate if MTE & EWA can be elicited using hypnosis, verbal suggestion and placebo, and to explore whether the expectation of receiving a psychedelic affects the intensity of subjective experience.
Methods: In a repeated measures design, psychedelic naive healthy adults of medium – high hypnotic susceptibility (score of 6 Harvard Group Scale for Hypnotic Susceptibility: form A) attended two sessions under differing expectancy conditions (open placebo vs “placebo psychedelic”). Participants were told they would receive either placebo or psilocybin (25mg) but all received an inert supplement. After hypnotic induction participants underwent four hypnosis conditions: suggestions for MTE, EWA, Alien Control of Movement (ACM), and a resting-state condition. Primary outcome: 10-point Likert scale (1 – 10 range) completed after each condition capturing the degree they experienced the suggestion. Secondary outcomes: the degree of hypnotic depth, absorption and relaxation in each condition (1-10 Likert scale), the Mystical Experience Questionnaire-30 item (MEQ-30) and guess of treatment (both post visit). The primary analysis utilised an intention-to treat principle with separate linear mixed models.
Results: Thirty-seven participants completed ≥1 session (mean age = 30.86, n = 18 female, mean Harvard = 8.38). Thirty-two participants completed both sessions. Participants guessed they received psilocybin on 62.86% of placebo psychedelic visits (n = 35, mean confidence: 71.10%) All open placebo visits were correctly identified.
All three suggested phenomena could be elicited (mean ratings: MTE 4.43, EWA 4.27, ACM 3.75). Higher hypnotic suggestibility associated to greater subjective effects, with a significant interaction to placebo psychedelic condition (MTE: β = 0.26, p = 0.011; EWA: β = 0.22, p = 0.009; ACM β = 0.28, p = 0.002). Guess of receiving psilocybin associated to greater hypnotic depth (5.41 vs 3.67, d = 0.61, p = 0.021) and absorption (6.52 vs 4.45, d = 0.89, p = 0.001). Trait suggestibility showed large effects across hypnosis measures (depth: d = 1.05; absorption: d = 1.06; relaxation: d = 8.13; all p < 0.001). High suggestibility associated to a large effect for post placebo psilocybin total MEQ-30 score (d = 0.93, p = 0.001), with mean score comparable to previous high-dose psilocybin studies (high suggestibility: mean = 62, SD = 32.5 vs Griffiths et al., 2016, Journal of psychopharmacology: mean = 63.64, SD = 3.56).
Conclusions: This study provides proof of concept that both MTE and EWA can be elicited with placebo and verbal suggestion. The findings indicate that non-pharmacological factors such as suggestibility and expectancy may play an important role in shaping psychedelic-like experiences.
Authors : Matt Butler (1); James Rucker (1); Mitul Mehta (1); Timothy Nicholson (1)
1- Institute of Psychiatry, Psychology & Neuroscience, King’s College London
Background. Psychoactive substances have been used as therapeutic interventions for functional neurological disorder (FND) since at least 1799. Abreaction therapy, involving hypnotic drugs plus suggestion, and therapeutic sedation, involving peri-anaesthetic drugs plus physiotherapy, have previously shown therapeutic benefit. Psychedelics (e.g. psilocybin) have recently shown cross-diagnostic promise across several neuropsychiatric disorders. There are cogent suggestions that some of the therapeutic effects of psychedelics may be modulated by placebo phenomena, such as expectancy and suggestibility. Furthermore, the interplay of psychotherapeutic preparation in psychedelic studies is not yet fully understood.
Methods. The PsiFUND (psilocybin in FND) study involved a single open-label administration of high-dose (25mg) psilocybin in a controlled clinical setting. Participants were required to have moderate-severe FND symptoms of any form despite ≥1 previous treatment. Participants underwent non-directive psychotherapeutic support, including three preparation sessions prior to dosing. Data were collected at screening and baseline (1 day prior to dosing) visits pertaining to: symptom severity (Clinical Global Impression severity [CGI-S] and improvement [CGI-I]), expectancy (Stanford Expectations of Treatment Scale [SETS]), suggestibility (Creative Imagination Scale [CIS] and Short Suggestibility Scale [SSS]), preparedness (Psychedelic Preparedness Scale [PPS]), and dose experience (Emotional Breakthrough Inventory [EBI], Psychological Insights Scale [PsyIS], Challenging Experiences Questionnaire [CEQ], and Ego-dissolution Inventory [EDI]). Paired-sample t-tests were used to compare SETS scores pre and post psychotherapeutic preparation. Bivariate correlations were used to assess the relationship of expectancy, suggestibility, and preparedness to clinical outcomes and dose experience.
Results. Twenty participants were recruited (75% female, mean age 43); 11 with functional motor symptoms, one with functional seizures alone, six with both subtypes, and two with persistent postural-perceptual dizziness. Mean CGI-S score at screening was 4.40 (SD 0.60), and at 3-month follow-up was 3.41 (1.18); mean CGI-I at follow-up was 2.71 (1.16). Mean EDI was 0.54 (SD 0.29). Mean SETS scores did not differ pre and post psychotherapeutic preparation for both the positive (4.21 [0.95] vs 4.48 [1.12], p=0.206) and negative subscales (2.55 [1.37] vs 2.95 [1.46], p=0.237).
Positive expectancy at baseline was not associated with CGI at follow-up, although was associated with measures of dose experience, including EBI (r=0.762, p = 0.006), PsyIS (r = 0.704, p=0.016), and EDI (r=0.538, p=0.014). Negative SETS subscale score was not associated with CGI or CEQ scores. PPS, SSS, and CIS scores were not associated with CGI or dose experience scores.
Discussion. This small open-label study suggests that psychotherapeutic preparation prior to psychedelic dosing in FND may not alter expectancy. Positive expectancy was associated with measures of dose experience, but not symptom change, suggesting expectancy-related processes may modulate psychedelic phenomenology independently of clinical response. Subjective dose intensity was consistent with other 25mg psilocybin trials. In contrast to our hypotheses, suggestibility and preparedness were not associated with dose experience or clinical response, although the Short Suggestibility Scale and Creative Imagination Scale are unlikely to capture the full dimensions of suggestibility. In summary, these data indicate that expectancy may be a key modulator of psychedelic phenomenology in FND, but further work is required to assess its impact on clinical symptoms.
Authors : Jon Stone (1)
1- University of Edinburgh
In this talk, I will discuss where we’ve been, where we are and where we are going with
clinical and research aspects of functional neurological disorder (FND). I will build on Quinton Deeleys talk on computational and neuroanatomical aspects with particular attention to placebo/hypnosis throughout and place FND in the context of other functional disorders.
Past- FND and hypnosis share a strong history, one which Nancy has played a special role in. After a flowering of interest in the late 19 th and early 20 th century, FND as Conversion Disorder in DSM-IV fell in to obscurity. It was a diagnosis of exclusion which couldn’t be made unless there was a recent stressful event. Neurologists who generally made the diagnosis were typically disinterested or ambivalent about whether FND was similar to feigned illness.
Present – FND is now firmly a diagnosis of inclusion with positive signs like Hoover’s sign, the tremor entrainment test and typical features of seizures. Entities like Persistent Postural Perceptual Dizziness and Functional Cognitive Disorder have pushed the boundaries of how we define FND. Positive diagnosis also allows us to approach communication with the patient in the same way as any other conditions and has helped us recognise a high frequency of FND comorbidity in patients with other neurological conditions. Studies of the neural underpinnings of the disorder don’t negate the importance of a psychological perspective – but do help rebalance it as a multidisciplinary condition – and not just the domain of psychiatry. Evidence-based treatment including hypnosis, physiotherapy, OT and psychological therapy will be discussed.
Future – The FND Society (fndsociety.org) has 1500 members and a biennial meeting that highlights new vigour in the field. We have new discoveries about important comorbidity, for example Autism/ADHD and joint hypermobility as well as novel approaches to treatment, including TMS, psychedelics and Virtual reality. The FND field has been particularly successful at working with patient-led organisations such as fndhope.org and fndaction.org.uk. Trials of new treatments are methodologically problematic when placebo itself in all its various forms is such a potentially powerful treatment itself in FND and many other conditions
Authors : Mahinda Yogarajah (1)
1- UCL Queen Square Institute of Neurology
Functional seizures (FS) offer a unique model for understanding how bodily attention, expectation, dissociation and altered agency can affect experience and action. I propose an interoceptive model in which FS arise when the “minimal self”, the pre-reflective sense of being an embodied subject, becomes unstable because of disrupted integration between interoceptive and exteroceptive signals. Within this framework, FS are not simply symbolic expressions of distress or learned behaviours, but maladaptive attempts to regulate a disturbed bodily self.
Controlled action requires interoceptive feedback to remain within an optimal range. Prior to a FS, the precision or weighting of interoceptive prediction errors may rapidly increase or decrease, driven by shifts in conscious and preconscious bodily attention. Increased bodily attention amplifies interoceptive precision, producing somatic/autonomic symptoms, over- embodiment and internal threat salience. This may lead to reduced movement, shutdown or hypomotile FS, conceptualised as freeze-like responses. Conversely, reduced or suppressed bodily attention weakens interoceptive precision, producing disembodiment, psychoform dissociation and loss of bodily presence. Hypermotile FS may then emerge as maladaptive active-inference responses: involuntary movement and autonomic activation restore sensory evidence for the body and re-establish embodied presence.
This model is supported by convergent empirical findings. In video-telemetry EEG data (n=88), heartbeat-evoked potential amplitude, an index of cortical processing of cardiac afferent signals and bodily attention, changes in opposite directions before different FS semiologies. Non-motile FS are preceded by increased HEP amplitude, whereas motile FS are preceded by reduced HEP amplitude; comparable changes are not seen before semiologically matched epileptic seizures. In functional syncope (n=60), a clinically overlapping non-motile phenotype, increased HEP amplitude tracks real-time bodily (but not emotional) symptom reporting, supporting the link between HEP, bodily attention and interoceptive precision.
Further support comes from a critical review of individuals with both epileptic and functional seizures. In this dual-diagnosis group prior epileptic seizures (ES) supply a highly salient embodied event around which later expectations, bodily vigilance and symptom attribution can organise. Across 80 studies (n = 2,275 dual-diagnosis patients) development of ES always preceded that of FS, while the dual-diagnosis group showed greater disease burden but fewer hypermotor events, fewer functional somatic syndromes, and lower rates of PTSD and dissociative disorders than individuals with FS alone. This pattern is consistent with a model in which epilepsy creates a high-precision “seizure prior” associated with bodily hypervigilance, increases interoceptive noise through epileptogenic and autonomic networks, and channels ambiguous bodily signals into a seizure-specific predictive framework.
Finally, post-ictal “paradoxical relief” provides a bridge to learning. In a video-telemetry cohort (n=176), relief after seizures was much more common in functional than epileptic seizures (OR=10) and was partially mediated by pre-ictal dissociation. This suggests that seizures may become reinforced because they reduce an intolerable pre-ictal state. The nervous system learns that it regulates dissociation, bodily threat or disembodiment.
This interoceptive model links altered consciousness, suggestibility, expectancy, subjective bodily experience, agency, and symptom learning in individuals with FS. It generates testable biomarkers and therapeutic targets, including interoceptive training, body-focused psychotherapy and interventions that uncouple relief from seizure expression.
Authors : Livia Asan (1, 2)
1- Department of Neurology, Centre for Translational and Behavioural Neurosciences, University Hospital Essen, University of Duisburg-Essen, Essen
2- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London
Functional neurological disorder (FND) is a common cause of neurological symptoms (Finkelstein et al., 2024). Patients frequently experience additional somatic symptoms, with pain among the most prevalent (Steinruecke et al., 2024). Increasingly, predictive processing within a Bayesian brain framework has been proposed as a key mechanism underlying symptom generation (Edwards et al., 2012). Within this framework, nocebo effects may not only exacerbate FND symptoms but could also play a causal role, suggesting that FND might reflect a “nocebo-tuned” Bayesian brain (Fiorio et al., 2022).
In this talk, the speaker will first illustrate how nocebo mechanisms can generate neurological symptoms. This will be demonstrated using headache as an example in data from patients with (a) headache reported following a health-related media scare, and (b) headache developing after risk communication during an informed consent procedure for lumbar puncture.
To investigate whether FND is associated with heightened negative expectations and increased susceptibility to nocebo effects in pain, we designed an experimental study comparing people with FND to non-clinical controls. The study examines nocebo hyperalgesia induced through a combination of verbal suggestion and classical conditioning, using a sham intervention involving pulsed electromagnetic fields purported to increase pain from an experimental electrical stimulus. Pain intensity and pain expectation ratings are used to assess group differences in the formation of negative expectations and the magnitude of nocebo hyperalgesia. Results from this currently ongoing study will be presented.
This talk invites the audience to discuss what we could learn from nocebo research for functional disorders and highlights key open questions regarding nocebo mechanisms in FND.
Authors : Mirta Fiorio (1); Ahmad Alawneh Anoud Izzat (1); Angela Marotta (1); Claudia Ricetti (1); Angela Sandri (1); Mehran Emadi Andani (1); Michele Tinazzi (1)
1- University of Verona (Italy)
In Bayesian models of perception, overly precise prior beliefs are recognized as a potential contributor to inaccurate perceptual inferences about incoming sensory stimuli. This viewpoint highlights the influential role of prior beliefs and expectations in shaping both perceptual and cognitive processes. Within the context of functional neurological disorders (FNDs), it has been suggested that the presence of abnormally precise prior beliefs, particularly in terms of negative expectations, might intensify symptom perception, potentially playing a role in both the onset and persistence of the disorder. This evidence highlights two factors. First, it is possible that a crucial role of expectation and maladaptive beliefs about one’s own body or functioning might be at the source of FND symptoms, through nocebo-like mechanisms. Second, this could imply that reversing participants’ negative expectations through a placebo procedure could induce symptom relief. In fact, this is consistent with findings showing that nocebo effects may be minimized by means of opposite (i.e., placebo) verbal suggestions and/or conditioning manipulations.
Guided by this logic, in this talk, I will first present a theoretical framework of shared neurocognitive mechanisms underlying FND and nocebo effects and then introduce an experimental paradigm to explore the placebo effect on force production, specifically in patients with functional weakness. In the latter, as a placebo intervention, peripheral low-frequency transcutaneous electrical nerve stimulation (TENS) was applied at inert frequencies, along with verbal information about its force-enhancing properties. At the end of the procedure, two placebo groups (one only verbally suggested and the other also conditioned) reached higher force levels, believed that TENS had been effective, and expected to perform better than the two control groups, which were not influenced by TENS (one with TENS application with overt information about its inert nature and one as a “natural history” group, without intervention).
The development of experimental models to test nocebo and placebo effects in FNDs may help elucidate the pathophysiology of the disease and provide insights into potential cognitive interventions to promote effective management of functional symptoms.
Authors : Arine Vlieger (1)
1- St. Antonius Hospital, Nieuwegein (Holland)
Approximately 40% of children with functional abdominal pain (FAP) or irritable bowel syndrome (IBS) demonstrate a clinically meaningful response in placebo arms of randomized controlled trials. In addition, gut-directed hypnotherapy is currently among the most effective treatments for these disorders. Together, these findings highlight the central role of positive expectations in paediatric disorders of the gut-brain interaction.
This lecture will present findings from our three recent studies investigating the impact of positive expectations in paediatric FAP and IBS. In the first randomized trial, 268 children with FAP or IBS received either mebeverine or placebo and were additionally exposed to different expectancy manipulations. Participants were either given a positive treatment message (you are lucky, you will get the real medication) or a neutral message (we don’t know whether you will receive placebo or active treatment). No difference was observed between mebeverine and placebo. However, positive labelling more than doubled treatment success compared with neutral labelling (33 versus 15%), demonstrating the powerful influence of treatment expectations on clinical outcomes.
In a second trial involving 228 children with FAP or IBS, peppermint oil capsules were compared with placebo capsules, while a third group received an impure placebo, consisting of peppermint sweets. They were informed that these sweets also contained peppermint oil. Treatment success was comparable across all three groups (45 to 54%), suggesting that impure placebos may offer a clinically relevant and ethically acceptable strategy to enhance symptom improvement in routine care.
Finally, results of a recent internationally survey will be presented, exploring expectations regarding pain medication among approximately 1000 children and 1000 parents from Australia, Sri Lanka, Nigeria, USA, Colombia, Greece and The Netherlands. These findings provide new insights into cultural similarities and differences in treatment expectations and their potential implications for clinical practice and future placebo-based interventions.
Authors : Anastassia Loukianov (1); Axel Cleeremans (1)
1- Consciousness Cognition & Computation Group, Université Libre de Bruxelles
Do people’s behaviors rely on what they perceive to be the case, or on what they believe to be the case? While this question may appear trivial at first glance, it becomes particularly relevant when subjective experience misrepresents reality, as in placebo or hypnotic suggestions. In clinical contexts, an inactive pill or procedure can elicit genuine physiological effects, yet the extent of these effects on core cognitive processes is still debated. At a more fundamental level, we focused on the role of experience in conflict tasks. Desender et al. (2014) showed that the Sequential Congruency Effect (SCE; Gratton, 1992) – an automatic adjustment of cognitive control after conflict – only emerges when conflict is consciously experienced, whereas van Gaal et al. (2010) argued in favor of unconsciously triggered adaptation. Both accounts, however, presuppose the presence of an objective conflict.
Here, taking inspiration from Palmeri & Flanery (1999) and the suggestions literature, we asked a different question: what happens when people experience conflict in the absence of any objective conflict? In a metacontrast masking orientation task (van Gaal et al., 2010), we first manipulated participants’ subjective appraisal of conflict through a sound-conditioning procedure: an auditory cue was associated with either a congruent or an incongruent prime- target relationship. During the experimental phase, unknown to participants, on half of the trials the prime was neutral, analogous to a placebo pill.
Our behavioral results show that (i) a full SCE pattern emerged after subjective conflict trials, mirroring the adaptation observed after objective conflict, and (ii) this effect depended on whether participants subjectively reported experiencing the conflict, rather than on the objective stimulus relationship. We found no evidence that the magnitude of this effect was modulated by participants’ suggestibility (SWASH; Lush et al., 2018).
Together, these findings emphasize that the subjective appraisal of conflict, rather than the objective signal itself, functions as a key trigger for conflict adaptation. We conclude that this involuntary adaptation behavior can be shaped by a constructed experience, even in the absence of any objective conflict signal.
Authors : Alexandre Coutté (1); Benjamin Moutardier (1); Nicolas Haas (1)
1- Laboratoire sur les Interactions Cognition, Action, Emotion Université Paris Nanterre
Imaginative suggestions are invitations to experience an imaginary state of affairs as if it were real (Kirsch & Braffman, 2001). They can modulate both motor behavior (Carli et al., 2006) and subjective experience (Markmann et al., 2023). While socio-cognitive frameworks like Response Set Theory (Kirsch & Lynn, 1997) emphasize the role of expectancy sets, Coutté et al. (2025) recently proposed a complementary embodied cognition account. According to this approach, mental imagery simulates real situations by reactivating past sensorimotor memory traces, which dynamically shape ongoing behaviour and experience.
The present study addressed two main objectives. First, at a fundamental level, we aimed at testing a key implication of the embodied account: suggestions activating highly efficient and vivid mental images should elicit stronger phenomenological and behavioral responses to suggestions. Grounded in Navon’s (1977) global precedence effect, which states that the perceptual system prioritizes holistic structures over constituent details (see also Bouvet et al., 2011), we hypothesized that suggestions structured with a “global attentional focus” would be easier to represent and would thus induce greater motor and experiential responses than those with a “local focus”.
Second, at a methodological level, we aimed to refine the paradigm of Coutté et al. (2025) by effectively aligning objective third-person (behavioural) and subjective first-person data over time, while strictly controlling the involuntariness of the responses.
In a non-hypnotic context, the participants listened to four counterbalanced 60-second scripts while maintaining their left arm stretched at shoulder height, palm upward. Suggestions invited them to imagine either a heavy object (a dictionary) or a light object (a paper sheet) placed on their hand. Attentional focus was manipulated across conditions by providing either a general description of the scene (Global focus) or a detailed description focusing on specific and localized features (Local focus). Vertical arm displacement was recorded online. Furthermore, a novel OpenSesame-based procedure was used to capture the temporal dynamics of subjective experience offline: participants listened to the scripts again and provided continuous retrospective ratings of both their perceived effort and their ease of visualization. A sense of agency scale was used as an exclusion criterion to ensure only genuine, involuntary responses were analyzed.
ANOVAS revealed that the arm lowered significantly more, and perceived effort increased, in the heavy compared to the light condition, specifically from the onset of the imagined interaction (30-40s interval). Furthermore, global scripts were rated as significantly easier to mentally represent than local ones. Consistent with this imagery facilitation, the heavy-light behavioral response was significantly enhanced under the global focus condition. These findings support an interpretation within the framework of embodied and situated cognition approaches, while demonstrating the heuristic value of tracking first- and third-person temporal dynamics.
Authors : Aymeric Guillot (1)
1- Laboratoire Interuniversitaire de Biologie de la Motricité, Université Claude Bernard Lyon 1, EA7424
Mental processes such as motor imagery and hypnosis are increasingly considered as powerful tools for optimizing performance across domains ranging from sport to clinical practice. While they are often studied separately, both rely on top-down mechanisms capable of shaping perception, cognition, and action. In this presentation, we first present the neurophysiological foundations of each approach. Then, we propose a unifying perspective in which they can be understood as complementary strategies for regulating experience. Auditory experience provides here a relevant model, as it can become intrusive and interfere with subsequent or concomitant performance. Drawing on recent advances in cognitive neuroscience, we introduce the concept of a continuum of auditory control, ranging from attentional selection to imagery-based modulation and hypnotic inhibition. Within this framework, individuals can “hear less” through distinct but related mechanisms, either by redirecting attention toward competing inputs, by actively reshaping internal representations of sound, or by inhibiting conscious access to auditory information altogether. We argue that motor imagery and hypnosis can be positioned within this continuum as two partially overlapping yet distinct modes of top-down control. Imagery primarily operates by transforming internal representations, while hypnosis may extend this capacity by modulating access to conscious experience itself. Rather than viewing these approaches as competing techniques, this perspective highlights their complementarity and potential for integration. By bridging research on perception, imagery, and hypnosis, this framework might offer new insights into the regulation of sensory experience and suggest practical applications for enhancing performance and managing intrusive stimuli in both sport and clinical contexts.
Authors : William McGeown (1)
1- University of Strathclyde
This lecture will examine how functional MRI has advanced understanding of hypnosis as a distinctive neurocognitive state. McGeown’s fMRI studies have contributed to a more precise account of what happens in the brain during hypnotic induction, particularly in highly hypnotizable individuals. Rather than viewing hypnosis simply as relaxation, imagination, compliance, or focused attention, this work suggests that hypnosis is associated with measurable changes in large-scale brain networks involved in self-referential processing, attention, executive control, and internally generated experience.
A central focus of the lecture will be McGeown’s finding that hypnotic induction is associated with reduced activity in anterior components of the default mode network, including medial and superior frontal regions. The default mode network is typically linked to self-reflection, autobiographical thought, mind-wandering, and internally oriented cognition. Reduced activity in this system during hypnosis may therefore help explain the subjective experience of absorption, altered self-awareness, and reduced spontaneous thought reported by many hypnotized individuals. Importantly, McGeown’s work suggested that this reduction was not simply accompanied by a typical compensatory increase in task-positive networks, supporting the idea that hypnosis may represent a distinctive mode of brain function rather than ordinary cognitive effort.
The lecture will also consider how his recent research extended this approach by examining individual differences in hypnotic suggestibility, subjective hypnotic depth, brain structure, and resting-state functional connectivity. These studies are important because they move hypnosis research beyond behavioural responsiveness alone and toward biologically informed markers of hypnotic capacity and hypnotic state. They also raise important questions about why some individuals enter hypnosis more readily, experience hypnotic suggestions more vividly, and show stronger therapeutic responses.
Particular attention will be given to the distinction between brain changes associated with hypnotic induction and those associated with specific hypnotic suggestions. Hypnotic induction may alter baseline network dynamics, including systems related to self-monitoring and internally directed awareness. In contrast, specific suggestions may selectively modulate sensory, motor, affective, or interoceptive systems depending on the content of the suggestion. This distinction is especially relevant for clinical applications, including hypnotic analgesia, motor symptoms, dissociation, and functional neurological disorder.
The presentation will place McGeown’s findings within broader debates about whether hypnosis should be understood as an altered state, a set of cognitive strategies, or an interaction between suggestibility, expectation, attention, and brain-network modulation. By linking subjective experiences of absorption and altered agency with objective neuroimaging findings, fMRI provides a valuable bridge between psychological theory and clinical practice.
Finally, the lecture will explore translational implications. If hypnosis can modulate networks involved in self-agency, symptom perception, attention, and embodied experience, neuroimaging may help explain why hypnosis can be clinically useful in pain, functional symptoms, and functional neurological disorder. Future fMRI studies embedded within treatment trials could test whether hypnosis not only improves symptoms, but also normalizes or reverses maladaptive brain-network patterns associated with functional disorders.
Authors : Anirban Dutta (1)
1- University of Birmingham
Functional Neurological Disorder (FND) is characterised by motor and sensory symptoms that are incongruent with recognised neurological disease and are associated with altered brain networks involved in agency, attention, motor control, and self-referential processing. Hypnotherapy is an emerging intervention for FND, but objective neural markers of hypnotic state and therapeutic response remain limited. Functional near-infrared spectroscopy (fNIRS) offers a portable and clinically deployable method for monitoring cortical haemodynamics during naturalistic therapeutic interaction. However, conventional frontal montages have limited sensitivity to medial parietal regions, including cortex overlying the precuneus and posterior cingulate cortex, which fMRI studies have implicated in hypnotic motor control and default-mode network modulation.
This lecture will present work using both portable frontal continuous-wave fNIRS and high-density whole-head time-domain fNIRS (TD-fNIRS) to monitor haemodynamic changes during hypnotherapy. Two complementary datasets were acquired across baseline, hypnotic induction, and suggestion phases. First, an 8-channel portable fNIRS device recorded one patient with FND and five healthy controls, with channels positioned over bilateral inferior frontal gyrus, including pars triangularis, and superior frontal/dorsolateral prefrontal regions. Second, four healthy participants were recorded using the Kernel Flow whole-head TD-fNIRS headset, comprising 52 dual-wavelength modules at 690 and 850 nm, providing dense source–detector coverage across the head. This whole-head approach was used to improve sensitivity to medial parietal cortex overlying the precuneus and posterior cingulate cortex.
Preprocessed haemodynamic signals were analysed using a general linear model with Gaussian basis functions spanning 60-second epochs. Resulting beta coefficients were used as features for machine-learning classification of hypnotic suggestion versus baseline, with models trained using 10-fold cross-validation and evaluated on the independent FND participant. Shapley additive explanation values were computed to assess feature importance and identify cortical regions contributing most strongly to classification.
The onset of hypnotic suggestion was associated with decreased oxyhaemoglobin and increased deoxyhaemoglobin concentrations, particularly within left frontal regions. A fine Gaussian support vector machine achieved the highest test accuracy of 66.7% in distinguishing hypnotic suggestion from baseline. Feature-importance analysis identified the left superior frontal gyrus as the most influential region, consistent with its proposed role in cognitive control, attentional modulation, and hypnotic suggestibility. In the whole-head TD-fNIRS dataset, suggestion-related oxygenation changes were also observed over medial parietal channels sampling cortex overlying the precuneus and posterior cingulate cortex, regions inaccessible to frontal-only montages.
These findings demonstrate the feasibility of using fNIRS to monitor brain responses during hypnotherapy. Combining portable frontal fNIRS with high-density whole-head TD-fNIRS captures both left-lateralised frontal markers and medial parietal default-mode changes, supporting a network-level account of hypnotic response. This approach may inform future fNIRS-guided hypnotherapy, neurofeedback, and neurorehabilitation strategies for FND and other neuropsychiatric conditions.
Authors : Abhijit Das (1)
1- University of Lancashire
Functional Neurological Disorder (FND) is increasingly understood as a disorder of abnormal brain-network integration involving motor control, salience processing, self-agency, interoception, and emotion regulation. Hypnosis has long been clinically relevant to FND, yet its mechanisms remain incompletely understood. This lecture will examine whether hypnosis may reverse, normalize, or functionally counteract network abnormalities reported in FND, with particular focus on the default mode network (DMN), salience network, executive control network, and sensorimotor systems.
A central theme will be the contrast between neuroimaging findings in hypnosis and those in FND. Resting-state hypnosis studies suggest that hypnosis is often associated with suppression or reconfiguration of DMN activity, particularly within posterior midline regions such as the posterior cingulate cortex and retrosplenial cortex. Hypnosis may also reduce coupling between executive control regions, such as the dorsolateral prefrontal cortex, and posterior DMN hubs, while increasing coupling between executive control and salience regions such as the insula. However, these effects are not uniform: some studies report no significant DMN change during neutral hypnosis, suggesting that the neural effects of hypnosis depend on hypnotic depth, suggestion content, task context, and individual hypnotizability.
By contrast, FND is commonly associated with reduced segregation between large-scale networks. Resting-state studies point to abnormal DMN integration with salience, executive, and sensorimotor networks, as well as altered dynamic connectivity. In functional seizures, reduced dynamism of dorsal DMN and executive networks has been described, while salience and sensorimotor networks may become more dynamic. Other analyses emphasize abnormal insula-driven co-activation states that are anti-correlated with the DMN, suggesting maladaptive switching between internally oriented and symptom-related salience states. Across FND phenotypes, PCC and precuneus abnormalities appear clinically important, although their direction varies by symptom type, analytic method, and disease stage.
Task-based studies provide a further point of comparison. During hypnosis, DMN regions often show reduced activation, although precuneus and related midline hubs may be selectively recruited during hypnotic suggestions involving altered agency, paralysis, or alien control. In FND, by contrast, PCC and precuneus are frequently recruited during symptom-relevant tasks involving negative emotion, interoceptive attention, self-monitoring, and disease-related bodily experience. This suggests that FND may involve excessive or maladaptive engagement of self-referential and interoceptive DMN hubs during symptom generation.
The lecture will propose that hypnosis may be therapeutically relevant because it can transiently reorganize the same networks that are dysregulated in FND. Rather than acting simply through relaxation or expectancy, hypnosis may alter self-monitoring, agency, attention, interoception, and motor prediction. The key question is whether repeated hypnotic intervention can produce durable normalization of DMN–salience– executive–motor network dynamics. The lecture will conclude by outlining how meta-analysis and mechanistic trials combining hypnosis, fMRI, fNIRS, and clinical outcomes could test whether hypnosis merely modulates symptoms or helps reverse maladaptive network changes in FND.
Authors : Ted Kaptchuk (1)
1- Harvard Medical School
Since the creation of “the powerful placebo” after World War II, the concept has been encrusted with misinformation. Until recently, the notion that honestly prescribed placebos could elicit clinical improvement was considered impossible. This talk will examine the historical background of open-label placebo (OLP) and the clinical evidence from more than twenty-four published RCTs that have shattered previous knowledge about placebo. Relevant neurobiological evidence will also be discussed. The validity of older placebo concepts, such as self-prophesy, expectation and conditioning, will be examined alongside newer models, including the Bayesian brain hypothesis and embodied cognition. OLPs relationship to functional disorders and centralization will be fundamental to the presentation.
Authors : Giulio Ongaro (1)
1- Hong Kong University of Science and Technology
The presentation offers a new understanding of the power of the ‘placebo effect.’ Popular views of this effect have oscillated between viewing it as a powerful phenomenon driven by a special class of mechanisms or as a powerless and insignificant quirk of the mind. Recent research challenges both views but has yet to replace them with a unified narrative of its own. As a result, the power of placebo effects, outside the field of placebo science itself, remains often misunderstood. I argue that there is a direct and simple way to characterize its power, one that is closely tied to the complementary concept of the ‘nocebo effect’ and does justice to the burgeoning scientific developments of the last two decades. I survey theoretical and experimental work—from the predictive processing framework and the neuroscience of nocebo effects, respectively—that suggests that placebo effects gain their power by countering nocebo effects, while remaining powerless to the extent that symptoms are tightly coupled to nociception or physiological disruption. Placebo responders, accordingly, might also be nocebo responders. Far from diminishing the phenomenon, this view reaffirms the clinical significance of the therapeutic ritual, particularly as a vital means of restoring psychosocial ‘balance.’
Authors : Leo Druart (1, 2); Parker Lay (1); Grayson Baird (1); Francesca Beaudoin (3); Michael Bernstein (1)
1- Warren Alpert Medical School of Brown University (United States)
2- Uppsala University (Sweden)
3- Department of Epidemiology, Brown University School of Public Health (United States)
Background: Recently, there has been a growing interest in using placebos transparently. Open-label placebos (OLP) are a type of placebo treatment in which patients are made aware that the treatment they’re receiving is pharmacologically inert. OLPs have been shown to reliably reduce symptoms compared to no treatment due to at least three important elements: the patient-provider interaction, the act of taking the treatment, and the rationale (i.e. the justification for the placebo). Previous research has shown that administering OLPs without any rationale provides little to no benefit, suggesting that the rationale is a necessary component of OLP treatments. Additionally, initial findings suggest OLPs may perform as well as deceptive placebos when administered with a convincing rationale. However, most OLP studies have used the same rationale (or some variation of it), and no studies to date have sought to optimize the rationale by comparing multiple rationales against each other. Therefore, the aim of the current study is to understand how different rationales might impact outcomes. We also address methodological limitations of prior OLP research, namely, lack of blinding and improper controls.
Objective: To explore the effect of rationale type on an OLP treatment (inactive pills) for chronic low back pain,
Design: Dismantling 4-arm randomized controlled trial.
Population: Remote study with United States residents aged 18 to 89 and presenting with chronic low back pain.
Methods: Participants were randomized before consent (Zelen randomization procedure) into one of 4 groups. This meant patients were not disappointed if they were assigned to the no-treatment condition as they did not know of the existence of other groups. Participants in a no-treatment group did not receive any OLPs. Participants in the three OLP groups were told to take an OLP pill twice daily for 21 days. The information participants were given about placebos varied. Those in the “Standard-OLP” group were provided with a rationale similar to those used in prior OLP trials. Those in the “Mindfulness-OLP” group were provided with a rationale emphasizing acceptance and the mind-body connection. Those in the “Control-OLP” group (and no-treatment group) were provided with a length-matched neutral message about pain demographics. This dismantling design allows us to simultaneously estimate the effects of whether a rationale is provided, the content of that rationale, the act of taking a pill, and the placebo effect. Pain intensity over 42 days is the primary outcome.
Results: To date, we recruited 272 subjects. Follow-up is still underway, and analysis will follow. The results will be presented at the conference.
Conclusions: This is the first trial to compare different explanations of OLPs and to investigate how components of OLPs may impact pain in a chronic low-back pain population. This trial also highlights novel ways to address limitations of prior OLP studies.
Trial Pre-Registration: NCT06931158
Authors : Urte Laukaityte (1)
1- ETH Zurich, Collegium Helveticum
There are good reasons to expect that symptom experience is an inferential process. Firstly, cognitive neuroscience frameworks that model cognition as relying on inference are on the rise. To the extent that capacities like perception are inferential, there is reason to suspect that symptom perception would be, too. Secondly, conceptualising symptom perception in this way has explanatory power. Functional neurological disorder (FND) has posed a complex challenge in medical theorising. Although the relevant terminological terrain is vast, roughly, ‘FND’ refers to the state of distressing clinical symptoms not grounded in underlying physiological disease or damage (Hallet et al., 2016).
The leading cognitive account involves shifting our understanding of symptom experience as a reliable read-out of potential underlying disease processes and instead viewing it as a type of inferential decision-making in the cognitive system that is prone to bias and mismatch (Van den Bergh et al., 2017; 2019). The inferential view of symptom experience accounts for the fact that there is mostly a close enough coupling between the two, while also allowing for the possibility of varying degrees of correspondence – at the far end of the spectrum lies FND with often extreme symptoms generated in the absence of disease or damage. There are also cases where the disease process is addressed but the symptoms do not subside, and those where there is significant physiological damage but little to no symptom experience. The inferential approach can account for various forms of possible mismatch.
The nature of symptom perception hence comprises an additional source of support for Stegenga’s (2018) formulation of gentle medicine, which advocates for deprioritising interventionist methods in clinical practice as a default, instead placing greater emphasis on more cautious, less aggressive treatments. He approached the subject from the point of view of medical nihilism, i.e. the claim that the effectiveness profile of most available medical interventions is much less impressive than generally assumed. I submit that there is also another reason to consider prioritising practices in accordance with the idea of gentle medicine – the likely prevalence of some degree of symptom amplification and/or functional symptoms in patient populations. I suggest it is plausible that the two could be related, too, such that part of the reason for subpar effectiveness of certain medical interventions designed to target disease processes may be connected with the relatively high prevalence of functional symptoms of one kind or another.
Given that symptom perception is inferential, it is easier to explain why certain kinds of placebo can be potent – a phenomenon that, I argue, we should be making more targeted use of in the clinic. As currently conceptualised, it is not the means itself but rather the psychosocial context of the clinician-patient interaction that is key for the placebo phenomenon (Kirmayer, 2016). I draw out some concrete implications of accepting that symptom perception may indeed be inferential. To be helpful, the physician should be using any relevant tools at their disposal to signal the possibility of change as a means of enhancing the therapeutic regimen.
Authors : Fabrice Berna (1); Guillaume Durand (2); Rémy Boussageon (3); Julien Nizard (4); François Paille (5); Laurence Verneuil (6)
1-Université de Strasbourg (France)
2- Nantes Université (France)
3- Université Claude Bernard Lyon 1 – Faculté des sciences (France)
4- Nantes Université (France)
5- Université de Lorraine (France)
6- Université Paris-Cité (France)
The growing interest in deprescribing drugs highlights the importance of re-evaluating prescriptions, but also of limiting inappropriate prescribing. This paper reflects on the ethical use of placebo as a way for limiting inappropriate prescribing. We focus on psychotropic drugs, but our reasoning may also concern other medical conditions. We analyze the conditions in which placebo are usually prescribed in medicine and analyze four situations in order to determine which would be best ethical. Although the use of placebos, whether pure (i.e., containing no active substance) or impure (i.e., containing active substances but used in a non- specific manner), is commonplace in medicine, patients are not duly informed: this practice respects neither patient autonomy nor freedom of choice. In contrast, the use of open-label placebos (i.e., prescribed to the patient in full transparency) solves this ethical problem. Importantly, informing the patient about the placebo does not seem to alter its therapeutic effect. Furthermore, the information given to the patient as part of the shared medical decision generally does not mention the benefits that a placebo could bring to the patient in place of a pharmacologically active drug. However, scientific data on the efficacy of placebo is available in randomized controlled trials or meta-analyses for almost all drugs. This effect is sometimes high under specific clinical conditions. We conclude that there is an ethical imperative to inform patients of the efficacy of a placebo in a clinical context where the prescription of a pharmacologically active drug is discussed. The open-label placebo option should become more systemic in medicine, particularly in psychological symptoms or conditions with a well-documented significant placebo effect. Aside from this ethical aspect, prescribing more placebos could be a way of combating overprescription, reducing inappropriate drug use and iatrogenia, and supporting the eco-responsible approach to prescribing in medicine.
Authors : Laurence J. Kirmayer (1)
1- McGill University
The study of placebo, hypnotic suggestion, and functional disorders has developed within largely separate research traditions, yet they share central questions: How do contexts, relationships, and expectations shape bodily experience, dysfunction, and healing? Building on recent work in cultural psychiatry, psychological anthropology and computational neuroscience, I develop an enactive inference framework that situates the precision-weighted predictive processing of expectation within a multilevel embodied and enacted cultural-ecosocial system. On this account, the processes that govern prediction are not confined to the brain but are enacted through bodily posture, interpersonal relationships, cultural affordances and regimes of attention in specific cultural contexts. The relevant cognitive processes involve a generative model that is distributed across the niche co-constituted by body, person, and social world. Within this multilevel architecture, functional symptoms can be understood as self-confirming predictions that, through looping effects spanning physiology, interpersonal interaction, and institutions, become stable forms of illness experience. Hypnosis and placebo reveal the converse: how meaning becomes physiologically efficacious. Recasting ethnographic research and the theory of symbolic healing in these terms, I argue that ritual heals through metaphoric transformation. The sufferer’s predicament is mapped onto a culturally coherent imaginal space, transformed according to its figurative logic, and then enacted in ways that carry the person into a new bodily state and social position. This model leads to a cultural-ecosocial approach that traces the psychophysiology of metaphor across levels, bridging dichotomies of meaning and mechanism to provide clinical guidance for working with the processes through which illness experience and healing unfold.