title: Stiffness judgments are affected by visual occlusion.
abstract: OBJECTIVE
  The current protocol for judging posteroanterior (PA) spinal stiffness has been shown to provide unreliable estimates of PA stiffness. It is possible that a failure to standardize therapists' use of vision in the test protocol partly contributes to the disagreement between raters. This study sought to establish whether vision affects stiffness judgments and so needs to be standardized when judging PA stiffness.
  
  
  METHODS
  Perceptual study using a mechanical device to provide stiffness stimuli with physiotherapists and lay people as judges.
  
  
  METHODS
  University psychophysics laboratory.
  
  
  METHODS
  Occlusion of vision via opaque goggles.
  
  
  METHODS
  Measures of interstimulus discriminability and bias.
  
  
  RESULTS
  Occluding vision had no effect on judges' ability to discriminate between stiffness stimuli; however, the same stimuli were judged as significantly stiffer under the visual occlusion condition.
  
  
  CONCLUSIONS
  The data from this study suggest that vision needs to be controlled when using manual tests to judge PA spinal stiffness.
authors: School of Physiotherapy, Faculty of Health Sciences, University of Sydney, Australia. pt_maher@cchs.su.edu.au
authors: C G
authors: CG
authors: Maher
authors: R D
authors: RD
authors: Adams
mesh_terms: D000704:Analysis of Variance; D016001:Confidence Intervals; D004867:Equipment Design; D006801:Humans; D010808:Physical Examination / Q000295:instrumentation / Q000379:methods; D026741:Physical Therapy Modalities; D011312:Pressure; D012680:Sensitivity and Specificity; D013122:Spinal Diseases / Q000175:diagnosis* / Q000503:physiopathology; D013131:Spine / Q000503:physiopathology*; D014796:Visual Perception