title: Unrealistic optimism and 'nosognosia': illness recognition in the healthy brain.
abstract: BACKGROUND
  At the centenary of research on anosognosia, the time seems ripe to supplement work in anosognosic patients with empirical studies on nosognosia in healthy participants. To this end, we adopted a signal detection framework to investigate the lateralized recognition of illness words--an operational measure of nosognosia--in healthy participants. As positively biased reports about one's current health status (anosognosia) and future health status (unrealistic optimism) have both been associated with deficient right hemispheric functioning, and conversely with undisturbed left hemispheric functioning, we hypothesised that more optimistic participants would adopt a more conservative response criterion, and/or display less sensitivity, when identifying illnesses in our nosognosia task; especially harmful illnesses presented to the left hemisphere via the right visual field.
  
  
  METHODS
  Thirty-two healthy right-handed men estimated their own relative risk of contracting a series of illnesses in the future, and then completed a novel computer task assessing their recognition of illness names presented to the left or right visual field. To check that effects were specific to the recognition of illness (rather than reflecting recognition of lexical items per se), we also administered a standard lateralized lexical decision task.
  
  
  RESULTS
  Highly optimistic participants tended to be more conservative in detecting illnesses, especially harmful illnesses presented to the right visual field. Contrary to expectation, they were also more sensitive to illness names in this half-field.
  
  
  CONCLUSIONS
  We suggest that, in evolutionary terms, unrealistic optimism may be an adaptive trait that combines a high perceptual sensitivity to threat with a high threshold for acknowledging its presence. The signal detection approach to nosognosia developed here may open up new avenues for the understanding of anosognosia in neurological patients.
authors.affiliation: ARC Centre of Excellence in Cognition and its Disorders, Department of Psychology, Royal Holloway, University of London, United Kingdom. Electronic address: ryantmckay@mac.com.
authors.forename: Ryan
authors.initials: R
authors.lastname: McKay
authors.affiliation: Neuropsychology Unit, Department of Neurology, Zürich University Hospital, Switzerland.
authors.forename: Andreas
authors.initials: A
authors.lastname: Buchmann
authors.affiliation: Neuropsychology Unit, Department of Neurology, Zürich University Hospital, Switzerland.
authors.forename: Nicole
authors.initials: N
authors.lastname: Germann
authors.affiliation: Neuropsychology Unit, Department of Neurology, Zürich University Hospital, Switzerland.
authors.forename: Shancong
authors.initials: S
authors.lastname: Yu
authors.affiliation: Neuropsychology Unit, Department of Neurology, Zürich University Hospital, Switzerland. Electronic address: peter.brugger@usz.ch.
authors.forename: Peter
authors.initials: P
authors.lastname: Brugger
mesh_terms: D000293:Adolescent; D000328:Adult; D000339:Affect / Q000502:physiology; D000377:Agnosia / Q000175:diagnosis* / Q000503:physiopathology*; D001921:Brain / Q000502:physiology*; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D008297:Male; D011930:Reaction Time / Q000502:physiology; D014794:Visual Fields / Q000502:physiology*; D055815:Young Adult
keywords: Anosognosia; Illness recognition; Nosognosia; Signal detection theory; Unrealistic optimism