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A Causal Role for Gastric Rhythm in Human Disgust Avoidance

2020; Elsevier BV; Volume: 31; Issue: 3 Linguagem: Inglês

10.1016/j.cub.2020.10.087

1879-0445

Camilla L. Nord, Edwin S. Dalmaijer, Thomas Armstrong, Kate Baker, Tim Dalgleish,

Face Recognition and Perception

Rotten food, maggots, bodily waste—all elicit disgust in humans. Disgust promotes survival by encouraging avoidance of disease vectors1Weinstein S.B. Buck J.C. Young H.S. A landscape of disgust.Science. 2018; 359: 1213-1214Crossref PubMed Scopus (87) Google Scholar but is also implicated in prejudice toward minority groups; avoidance of environmentally beneficial foods, such as insect protein; and maladaptive avoidance behavior in neuropsychiatric conditions.2Taylor K. Disgust is a factor in extreme prejudice.Br. J. Soc. Psychol. 2007; 46: 597-617Crossref PubMed Scopus (61) Google Scholar, 3Power M. Dalgleish T. Cognition and Emotion: From Order to Disorder. Psychology, 2015Crossref Scopus (58) Google Scholar, 4Olatunji B.O. McKay D. Disgust and psychiatric illness: have we remembered?.Br. J. Psychiatry. 2007; 190: 457-459Crossref PubMed Scopus (54) Google Scholar, 5Phillips M.L. Senior C. Fahy T. David A.S. Disgust--the forgotten emotion of psychiatry.Br. J. Psychiatry. 1998; 172: 373-375Crossref PubMed Scopus (163) Google Scholar Unlike fear, pathological disgust is not improved substantially by exposure therapy clinically,6Mason E.C. Richardson R. Treating disgust in anxiety disorders.Clin. Psychol. Sci. Pract. 2012; 19: 180-194Crossref Scopus (60) Google Scholar nor in experimental work does behavioral avoidance of disgusting images habituate following prolonged exposure.7Dalmaijer E. Lee A. Leiter R. Brown Z. Armstrong T. Forever yuck: oculomotor avoidance of disgusting stimuli resists habituation.J. Exp. Psychol. Gen. 2020; (Published online October 29, 2020)https://doi.org/10.17863/CAM.59278Crossref Google Scholar,8Armstrong T. Stewart J.G. Dalmaijer E.S. Rowe M. Danielson S. Engel M. Bailey B. Morris M. I've seen enough! Prolonged and repeated exposure to disgusting stimuli increases oculomotor avoidance.PsyArxiv. 2019; https://doi.org/10.31234/osf.io/hgkpuCrossref Google Scholar Under normal physiological conditions, perception of disgusting stimuli disrupts myoelectrical rhythms in the stomach,9Koch K.L. Physiology of nausea.in: Koch K. Hasler W. Nausea and Vomiting. Springer, 2017: 1-13Crossref Scopus (3) Google Scholar, 10Stern R.M. The psychophysiology of nausea.Acta Biol. Hung. 2002; 53: 589-599Crossref PubMed Scopus (42) Google Scholar, 11Harrison N.A. Gray M.A. Gianaros P.J. Critchley H.D. The embodiment of emotional feelings in the brain.J. Neurosci. 2010; 30: 12878-12884Crossref PubMed Scopus (199) Google Scholar, 12Shenhav A. Mendes W.B. Aiming for the stomach and hitting the heart: dissociable triggers and sources for disgust reactions.Emotion. 2014; 14: 301-309Crossref PubMed Scopus (52) Google Scholar, 13Zhou R. Hu S. Effects of imagining eating favorable and unfavorable foods on gastric motility indexed by electrogastrographic (EGG) activities.Percept. Mot. Skills. 2006; 103: 829-833Crossref PubMed Google Scholar inducing gastric dysrhythmias that correlate with neural signatures of disgust.11Harrison N.A. Gray M.A. Gianaros P.J. Critchley H.D. The embodiment of emotional feelings in the brain.J. Neurosci. 2010; 30: 12878-12884Crossref PubMed Scopus (199) Google Scholar However, the causal role of gastric rhythm in disgust avoidance is unknown. We manipulated gastric rhythm using domperidone, a peripheral dopamine D2/D3 antagonist and common anti-emetic, at a dose (10 mg) that acts to convert gastric dysrhythmias to normal rhythms.9Koch K.L. Physiology of nausea.in: Koch K. Hasler W. Nausea and Vomiting. Springer, 2017: 1-13Crossref Scopus (3) Google Scholar In a preregistered, randomized, double-blind, placebo-controlled crossover design in 25 healthy volunteers (aged 18–25), we measured the effects of domperidone on core disgust avoidance, using eye tracking to measure implicit (oculomotor) avoidance of disgusting images (feces) before and after an "exposure" intervention (monetary reinforcement for looking at disgusting images).7Dalmaijer E. Lee A. Leiter R. Brown Z. Armstrong T. Forever yuck: oculomotor avoidance of disgusting stimuli resists habituation.J. Exp. Psychol. Gen. 2020; (Published online October 29, 2020)https://doi.org/10.17863/CAM.59278Crossref Google Scholar,8Armstrong T. Stewart J.G. Dalmaijer E.S. Rowe M. Danielson S. Engel M. Bailey B. Morris M. I've seen enough! Prolonged and repeated exposure to disgusting stimuli increases oculomotor avoidance.PsyArxiv. 2019; https://doi.org/10.31234/osf.io/hgkpuCrossref Google Scholar We find that domperidone significantly reduces oculomotor disgust avoidance following incentivized exposure. This suggests that domperidone may weaken the "immunity" of disgust to habituation, putatively by reducing gastric dysrhythmias during incentivized engagement with disgusting stimuli. This indicates a causal role for disgust-related visceral changes in disgust avoidance, supporting the hypothesis that physiological homeostasis contributes to emotional experience.