title: Stimulus-dependent modulation of visual neglect in a touch-screen cancellation task.
abstract: OBJECTIVE
  Patients with left-sided neglect frequently show omissions and repetitive behavior on cancellation tests. Using a touch-screen-based cancellation task, we tested how visual feedback and distracters influence the number of omissions and perseverations.
  
  
  METHODS
  Eighteen patients with left-sided visual neglect and 18 healthy controls performed four different cancellation tasks on an iPad touch screen: no feedback (the display did not change during the task), visual feedback (touched targets changed their color from black to green), visual feedback with distracters (20 distracters were evenly embedded in the display; detected targets changed their color from black to green), vanishing targets (touched targets disappeared from the screen).
  
  
  RESULTS
  Except for the condition with vanishing targets, neglect patients had significantly more omissions and perseverations than healthy controls in the remaining three subtests. Both conditions providing feedback by changing the target color showed the highest number of omissions. Erasure of targets nearly diminished omissions completely. The highest rate of perseverations was observed in the no-feedback condition. The implementation of distracters led to a moderate number of perseverations. Visual feedback without distracters and vanishing targets abolished perseverations nearly completely.
  
  
  CONCLUSIONS
  Visual feedback and the presence of distracters aggravated hemispatial neglect. This finding is compatible with impaired disengagement from the ipsilesional side as an important factor of visual neglect. Improvement of cancellation behavior with vanishing targets could have therapeutic implications.
authors.affiliation: Department of Neuropsychology, Graduate School of Systemic Neurosciences, Schoen Klinik Bad Aibling.
authors.forename: Ingo
authors.initials: I
authors.lastname: Keller
authors.affiliation: Graduate School of Systemic Neurosciences, Ludwig-Maximilians-University.
authors.forename: Katharina
authors.initials: K
authors.lastname: Volkening
authors.affiliation: Clinical Neuropsychology Unit and Outpatient Service, Saarland University.
authors.forename: Ruta
authors.initials: R
authors.lastname: Garbacenkaite
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D056228:Feedback, Sensory / Q000502:physiology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D010468:Perceptual Disorders / Q000523:psychology*; D013028:Space Perception / Q000502:physiology*; D014110:Touch / Q000502:physiology*