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Fitts' law, motor control, motor performance, older adults, task complexity, visual conditions



  1. Giuffrida, Clare G. PhD, OTR/L
  2. Posse, Maria Cristina MS, OT
  3. Cauraugh, James PhD


With the increasing aging population and technology advances, occupational therapists and other healthcare professionals are uniquely positioned to examine how changes associated with aging and environmental factors support or constrain the functioning of senior adults. This study investigated how task complexity and vision (functions critical for engaging in everyday tasks) influenced a rapid aiming task performed by a group of healthy senior adults (N = 18) between the ages of 60 and 80. Manipulating task complexity and visual information conditions provided insights into response preparation/reaction time, movement time, total time, and arm velocity profiles. Separate within-subjects design analysis of variance indicated that, with increasing task complexity and a restricted visual environment, senior adults performed more slowly as compared with their performance in a visually enhanced and less complex environment. Consistent with Fitts' law, senior adults' movement time significantly increased as task complexity increased. Moreover, movement time was longer for the no-vision conditions whereas conversely reaction time was shorter in the no-vision conditions. Velocity profiles were similar to those described in the literature on senior adults with flattened peaks and online adjustments evident in the vision conditions, whereas in the no-vision conditions velocity profiles were more symmetric and preplanned. Given that senior adults' aiming performance is affected by age-related changes and environmental complexity, this study provides insights to optimizing their performance in adapting and enhancing simple everyday tasks involving pointing and aiming. Implications include redesign of keyboards or use of accessibility devices to offset their age-related response slowness. Thus, this study provides empirical support to designers for implementing visibility features and varying target sizes to enhance seniors' participation in everyday environments.