title: Vestibular stimulation attenuates unrealistic optimism.
abstract: BACKGROUND
  Unrealistic optimism refers to the pervasive tendency of healthy individuals to underestimate their likelihood of future misfortune, including illness. The phenomenon shares a qualitative resemblance with anosognosia, a neurological disorder characterized by a deficient appreciation of manifest current illness or impairment. Unrealistic optimism and anosognosia have been independently associated with a region of right inferior frontal gyrus, the pars opercularis. Moreover, anosognosia is temporarily abolished by vestibular stimulation, particularly by irrigation of the left (but not right) ear with cold water, a procedure known to activate the right inferior frontal region. We therefore hypothesized that left caloric stimulation would attenuate unrealistic optimism in healthy participants.
  
  
  METHODS
  Thirty-one healthy right-handed adults underwent cold-water caloric vestibular stimulation of both ears in succession. During each stimulation episode, and at baseline, participants estimated their own relative risk of contracting a series of illnesses in the future.
  
  
  RESULTS
  Compared to baseline, average risk estimates were significantly higher during left-ear stimulation, whereas they remained unchanged during right-ear stimulation. Unrealistic optimism was thus reduced selectively during cold caloric stimulation of the left ear.
  
  
  CONCLUSIONS
  Our results point to a unitary mechanism underlying both anosognosia and unrealistic optimism, and suggest that unrealistic optimism is a form of subclinical anosognosia for prospective symptoms.
authors.affiliation: ARC Centre of Excellence in Cognition and its Disorders, and Department of Psychology, Royal Holloway, University of London, United Kingdom. ryantmckay@mac.com
authors.forename: Ryan
authors.initials: R
authors.lastname: McKay
authors.forename: Corinne
authors.initials: C
authors.lastname: Tamagni
authors.forename: Antonella
authors.initials: A
authors.lastname: Palla
authors.forename: Peter
authors.initials: P
authors.lastname: Krummenacher
authors.forename: Stefan C A
authors.initials: SC
authors.lastname: Hegemann
authors.forename: Dominik
authors.initials: D
authors.lastname: Straumann
authors.forename: Peter
authors.initials: P
authors.lastname: Brugger
mesh_terms: D000328:Adult; D000377:Agnosia / Q000503:physiopathology; D001294:Attitude to Health; D002150:Caloric Tests; D003080:Cold Temperature; D005260:Female; D005625:Frontal Lobe / Q000502:physiology*; D006801:Humans; D008297:Male; D010465:Perception; D010812:Physical Stimulation / Q000379:methods; D012306:Risk; D014722:Vestibule, Labyrinth / Q000502:physiology*; D055815:Young Adult
keywords: Anosognosia; Caloric irrigation; Positive illusions; Unrealistic optimism; Vestibular stimulation