title: Complex tactile performance in low visibility: the effect of nitrogen narcosis.
abstract: BACKGROUND
  In a task-environment where visibility has deteriorated, individuals rely heavily on tactile performance (perception and manipulation) to complete complex tasks. When this happens under hyperbaric conditions, factors like nitrogen narcosis could influence a person's ability to successfully complete such tasks.
  
  
  OBJECTIVE
  To examine the effect of nitrogen narcosis on a complex neuropsychological task measuring tactile performance at a pressure of 608 kPa (6 atm abs), in the absence of visual access to the task.
  
  
  METHODS
  In a prospective cross-over study, 139 commercial divers were tested in a dry chamber at 101.3 kPa and 608 kPa. They completed the Tupperware Neuropsychological Task (TNT) of tactile performance without visual access to the task, and completed questionnaires to provide psychological and biographical data, which included trait anxiety and transient mood states, as well as formal qualifications and technical proficiency.
  
  
  RESULTS
  A significant decrement (9.5%, P < 0.001) in performance on the TNT at depth was found, irrespective of the sequence of testing. Generally, neither the psychological nor biographical variables showed any significant effect on tactile performance. Tactile performance on the surface was a good indicator of performance at depth.
  
  
  CONCLUSIONS
  These findings have practical implications for professional diving where conditions of low visibility during deeper diving occur. Recommendations are made towards managing potential impairments in tactile performance, such as pre-dive practical learning ('rehearsal') as an aid to successful completion of tasks.
authors.affiliation: Division of Community Health, Faculty of Medicine and Health Sciences, Stellenbosch University, PO Box 494 Simon's Town, 7995, South Africa, Phone: +279-(0)21-782-7030, E-mail: chvanwijk@gmail.com.
authors.forename: Charles H
authors.initials: CH
authors.lastname: van Wijk
authors.affiliation: Division of Community Health, Faculty of Medicine and Health Sciences, Stellenbosch University, South Africa.
authors.forename: Willem A J
authors.initials: WA
authors.lastname: Meintjes
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000704:Analysis of Variance; D001274:Atmospheric Pressure; D018592:Cross-Over Studies; D004242:Diving / Q000502:physiology* / Q000523:psychology; D004522:Educational Status; D056228:Feedback, Sensory; D005260:Female; D006801:Humans; D007222:Inert Gas Narcosis / Q000503:physiopathology* / Q000523:psychology; D008297:Male; D009483:Neuropsychological Tests; D011446:Prospective Studies; D012623:Seawater; D012683:Sensory Deprivation / Q000502:physiology*; D013647:Task Performance and Analysis; D014110:Touch / Q000502:physiology*; D055698:Touch Perception / Q000502:physiology*; D055815:Young Adult
keywords: Nitrogen narcosis; deep diving; diving research; performance; psychology