title: Memory and metacognition in dangerous situations: investigating cognitive impairment from gas narcosis in undersea divers.
abstract: OBJECTIVE
  The current study tested whether undersea divers are able to accurately judge their level of memory impairment from inert gas narcosis.
  
  
  BACKGROUND
  Inert gas narcosis causes a number of cognitive impairments, including a decrement in memory ability. Undersea divers may be unable to accurately judge their level of impairment, affecting safety and work performance.
  
  
  METHODS
  In two underwater field experiments, performance decrements on tests of memory at 33 to 42 m were compared with self-ratings of impairment and resolution. The effect of depth (shallow [I-II m] vs. deep [33-42 m]) was measured on free-recall (Experiment I; n = 41) and cued-recall (Experiment 2; n = 39) performance, a visual-analogue self-assessment rating of narcotic impairment, and the accuracy of judgements-of-learning JOLs).
  
  
  RESULTS
  Both free- and cued-recall were significantly reduced in deep, compared to shallow, conditions. This decrement was accompanied by an increase in self-assessed impairment. In contrast, resolution (based on JOLs) remained unaffected by depth. The dissociation of memory accuracy and resolution, coupled with a shift in a self-assessment of impairment, indicated that divers were able to accurately judge their decrease in memory performance at depth.
  
  
  CONCLUSIONS
  These findings suggest that impaired self-assessment and resolution may not actually be a symptom of narcosis in the depth range of 33 to 42 m underwater and that the divers in this study were better equipped to manage narcosis than prior literature suggested. The results are discussed in relation to implications for diver safety and work performance.
authors.forename: Malcolm
authors.initials: M
authors.lastname: Hobbs
authors.forename: Philip A
authors.initials: PA
authors.lastname: Higham
authors.forename: Wendy
authors.initials: W
authors.lastname: Kneller
mesh_terms: D000328:Adult; D003072:Cognition Disorders / Q000503:physiopathology*; D004242:Diving; D005260:Female; D006801:Humans; D007222:Inert Gas Narcosis / Q000503:physiopathology* / Q000523:psychology*; D008297:Male; D008569:Memory Disorders / Q000503:physiopathology*; D011939:Mental Recall / Q000502:physiology*; D008875:Middle Aged; D009483:Neuropsychological Tests; D055815:Young Adult