title: Effects of uni- and multimodal cueing on handrail grasping and associated gaze behavior in older adults.
abstract: BACKGROUND
  It appears that age-related changes in visual attention may impair ability to acquire the visuospatial information needed to grasp a handrail effectively in response to sudden loss of balance. This, in turn, may increase risk of falling. To counter this problem, we developed a proximity-triggered cueing system that provides a visual cue (flashing lights) and/or verbal cue ("attention use the handrail") to attract attention to the handrail. This study examined the effect of handrail cueing on grasping of the rail and associated gaze behavior in a large cohort (n=160) of independent and ambulatory older adults (age 64-80).
  
  
  METHODS
  The handrail and cueing system was mounted on a large (2 m×6 m) motion platform configured to simulate a real-life environment. Subjects performed a daily-life task that required walking to the end of the platform, which was triggered to perturb balance by moving suddenly when they were adjacent to the rail. To prevent adaptation, each subject performed only one trial, and a deception was used to ensure that the perturbation was truly unexpected. Each subject was assigned to one of four cue conditions: visual, verbal, multimodal (visual-plus-verbal) or no cue.
  
  
  RESULTS
  Verbal cueing attracted overt visual attention to the handrail and markedly increased proactive grasping (prior to the onset of the balance perturbation) particularly when delivered unimodally. Subjects were otherwise much more likely to grasp the rail in reaction to the perturbation. A possible trend for visual cueing to improve the accuracy of these reactions was offset by adverse effects on reaction speed and on frequency of proactive grasping.
  
  
  CONCLUSIONS
  The results support the viability of using unimodal verbal cueing to reduce fall risk by increasing proactive handrail use. Conversely, they do not strongly support use of visual cueing (either alone or in combination with verbal cueing) and suggest that it may even have adverse effects. Further study is needed to evaluate effects of handrail cueing in a wide range of populations and real-life settings.
authors.affiliation: Toronto Rehabilitation Institute (University Health Network), Canada; Centre for Studies in Aging, Sunnybrook Health Sciences Centre, Canada.
authors.forename: Sandra M
authors.initials: SM
authors.lastname: McKay
authors.forename: Julia E
authors.initials: JE
authors.lastname: Fraser
authors.forename: Brian E
authors.initials: BE
authors.lastname: Maki
mesh_terms: D000058:Accidental Falls / Q000517:prevention & control*; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging; D015331:Cohort Studies; D003463:Cues; D005133:Eye Movements; D005260:Female; D005403:Fixation, Ocular; D005684:Gait; D018737:Hand Strength; D006801:Humans; D008297:Male; D008875:Middle Aged; D004856:Postural Balance
keywords: Aging; Falls prevention; Postural balance; Reach-to-grasp reactions; Stair safety; Visual attention