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The way we experience and estimate time – subjective time – does not systematically correspond to objective time (the physical duration of an event). Many factors can influence subjective time and lead to mental dilation or compression of objective time. The emotional valence of stimuli or the levels of attention or expectancy are known to modulate subjective time even though objective time is constant. Hypnosis too is known to alter people’s perception of time. However, it is not known whether hypnotic time distortions are intrinsic perceptual effects, based for example on the changing rate of an internal clock, or rather the result of a response to demand characteristics. Here we distinguished the theories using the logic of the El Greco fallacy. When participants initially had to compare the duration of two successive events —with the same duration — while in “trance,” they responded that the second event was on average longer than the first event. As both events were estimated in “trance,” if hypnosis had impacted on an internal clock, they should have been affected to the same extent. Conversely, when only the first event was in “trance,” there was no difference in perceived duration. The findings conform to an El Greco fallacy effect and challenge theories of hypnotic time distortion arguing that “trance” itself changes subjective time.

Chronic Obstructive Pulmonary Disease (COPD) is a highly prevalent and debilitating respiratory condition, characterized by chronic airflow limitation, breathlessness, and other persistent respiratory symptoms. Critically, patients suffering from COPD often find themselves trapped in a vicious comorbidity cycle: while breathlessness and increased respiratory rate are known inducers of anxiety, the latter have been shown in turn to exacerbate breathlessness and chest discomfort. Hypnosis holds great potential for the simultaneous complementary management of anxiety and breathlessness in COPD. It is an inexpensive psychological intervention tailored to the patient’s own experience, convenient in terms of logistics and implementation. In this short qualitative review, we present hypnosis’ structural, cognitive, and neural fundamentals, and assess existing instances of hypnosis use in the treatment of anxiety, depression, and respiratory disease. We then discuss its potential as a tool for improving health-related quality of life and the self-management of COPD within (and beyond) pulmonary rehabilitation.

Complementary psychological care is recommended for COPD, as it significantly reduces anxiety, and boosts the pulmonary rehabilitation efficacy. In a precedent trial (HYPNOBPCO_1, ISRCTN10029862), administering a single hypnosis session was linked to reduced anxiety and improved breathing mechanics in intermediate and advanced COPD patients. However, whether hypnosis could improve self-management of anxiety and dyspnea in COPD during pulmonary rehabilitation is yet to be investigated.This is the protocol for HYPNOBPCO_2, a 2-arm, cluster-randomised, statistician-blinded superiority monocenter trial (NCT04868357). Its aim is to assess the efficacy of hypnosis as a tool to manage anxiety and dyspnea during a Pulmonary Rehabilitation Program (PRP). Clusters of COPD patients eligible to the conventional hospital-based PRP at the Centre Hospitalier de Bligny (CHB), will be randomised and evenly allocated into two parallel arms: “Hypnosis” (treatment) and “Relaxation” (active control). “Hypnosis” will consist of the CHB's conventional 4-week group PRP, supplemented by 2 educational sessions for teaching self-hypnosis. “Relaxation” will be identical, except standard relaxation exercises will be taught instead. Primary end-point will consist of assessing weekly changes in anxiety throughout the PRP, additional to total anxiety change after treatment completion. Anxiety will be determined by the 6-item version of the State-Trait Anxiety Inventory (STAI-6). Secondary outcomes will include change in the 6-minute walking test and the COPD assessment test (CAT). Further follow-up outcomes will include CAT and STAI-6 retests, re-hospitalization rate, action plan use, and persistence in self-hypnosis use, throughout the 12 weeks ensuing PRP completion.

To test the specific effects of hypnosis on the attentional components of visual awareness, we developed a posthypnotic suggestion for peripheral visual inattention inspired on the “tunnel vision” symptom of the Balint Syndrome. We constructed a dual-target visibility and discrimination paradigm, in which single-digit numerical targets were placed both on the hypnotically affected peripheral space and on the remaining undisturbed central area. Results were 3-fold: (i) when compared to participants of Low hypnotic susceptibility (Lows), highly susceptible participants (Highs) presented decreased subjective visibility; (ii) Highs did not show dual-task interference from peripheral targets (an effect of unconscious processing) during hypnotic suggestion to not attend them, but Lows did; (iii) nevertheless, when asked to execute a discrimination task over these same targets, Highs performed with the same accuracy as Lows. These results suggest that the hypnotic manipulation of visuospatial attention did produce an experiential change in Highs, but not one that could be mapped onto interference at a single (conscious or unconscious) level of processing. Rather, we posit that Highs simultaneously displayed (i) a fluctuation in awareness of peripheral targets coherent with the suggestion and (ii) a control strategy that involved removing hypnotically unattended targets from the task set whenever task instructions would allow for it. In light of these findings, we argue that hypnosis cannot be used as a tool to restrict the processing of otherwise supraliminal stimulation to subliminal levels.

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Verbal hints can bias perceptual decision-making, even when the information they provide is false. What makes individuals more or less susceptible to such influences, however, remains unclear. Here, we inquire whether suggestibility to social influence, a high-level trait measured by a standard suggestibility scale, could predict changes in perceptual judgments. We asked naive participants to indicate the dominant color in a series of stimuli after giving them a short, false verbal statement about which color would likely dominate. We found that this statement biased participants’ perceptual judgments of the dominant color, as shown by a correlated shift of their discrimination performance, confidence judgments, and response times. Crucially, this effect was more pronounced in participants with higher levels of susceptibility to social influence. Together, these results indicate that social suggestibility can determine how much simple (albeit false) verbal hints influence perceptual judgments.