title: Image jitter enhances visual performance when spatial resolution is impaired.
abstract: OBJECTIVE
  Visibility of low-spatial frequency stimuli improves when their contrast is modulated at 5 to 10 Hz compared with stationary stimuli. Therefore, temporal modulations of visual objects could enhance the performance of low vision patients who primarily perceive images of low-spatial frequency content. We investigated the effect of retinal-image jitter on word recognition speed and facial emotion recognition in subjects with central visual impairment.
  
  
  METHODS
  Word recognition speed and accuracy of facial emotion discrimination were measured in volunteers with AMD under stationary and jittering conditions. Computer-driven and optoelectronic approaches were used to induce retinal-image jitter with duration of 100 or 166 ms and amplitude within the range of 0.5 to 2.6° visual angle. Word recognition speed was also measured for participants with simulated (Bangerter filters) visual impairment.
  
  
  RESULTS
  Text jittering markedly enhanced word recognition speed for people with severe visual loss (101 ± 25%), while for those with moderate visual impairment, this effect was weaker (19 ± 9%). The ability of low vision patients to discriminate the facial emotions of jittering images improved by a factor of 2. A prototype of optoelectronic jitter goggles produced similar improvement in facial emotion discrimination. Word recognition speed in participants with simulated visual impairment was enhanced for interjitter intervals over 100 ms and reduced for shorter intervals.
  
  
  CONCLUSIONS
  Results suggest that retinal-image jitter with optimal frequency and amplitude is an effective strategy for enhancing visual information processing in the absence of spatial detail. These findings will enable the development of novel tools to improve the quality of life of low vision patients.
authors.affiliation: Department of Life Sciences, Glasgow Caledonian University, Glasgow, UK.
authors.forename: Lynne M
authors.initials: LM
authors.lastname: Watson
authors.forename: Niall C
authors.initials: NC
authors.lastname: Strang
authors.forename: Fraser
authors.initials: F
authors.lastname: Scobie
authors.forename: Gordon D
authors.initials: GD
authors.lastname: Love
authors.forename: Dirk
authors.initials: D
authors.lastname: Seidel
authors.forename: Velitchko
authors.initials: V
authors.lastname: Manahilov
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D004644:Emotions / Q000502:physiology; D005133:Eye Movements / Q000502:physiology; D005149:Facial Expression; D005260:Female; D006801:Humans; D008268:Macular Degeneration / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D010364:Pattern Recognition, Visual / Q000502:physiology*; D010469:Perceptual Distortion / Q000502:physiology*; D012160:Retina / Q000503:physiopathology*; D015354:Vision, Low / Q000503:physiopathology*; D019987:Persons with Visual Disabilities