Item individuation, tracking, and tasks that involve visual-motor coordination

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Whether you are turning left across busy traffic as you drive home, monitoring the positions of your teammates and the puck as you play hockey, capturing dropped coins as they roll away in all directions, or simply trying not to lose your children as you exit a crowded auditorium, there are times when you need to keep track of the positions of several moving items at once. This ability is called multiple-object tracking. Under normal conditions, young adults can track 3-5 moving items at once, though this ability declines with age. Multiple-object tracking predicts things as diverse as crash risk in older drivers to performance in elite athletes. It seems to be related to visual-motor coordination, but why is it related? Is multiple-object tracking actually part of coordinated action? Or does the relationship occur because multiple-object tracking and visually coordinated action draw upon a common limited resource -- general attention -- a resource shared between all senses and with all cognitive tasks, even ones that do not require overt actions (e.g. thinking about the day's events). There are age-related changes in attention. Is this why older adults cannot track as many at once? The answers to these questions are relevant both to understanding age-related deficits and designing effective interventions to overcome them. This research will involve studying the relationship between multiple-object tracking and two coordinated tasks: visually guided touch and driving an automobile. We will be investigating performance in young and older adults (18-25 years, 65+ years). To measure visually guided touch, we will have participants trying to "catch" specific moving items among others on a touch screen. Visually coordinated steering, headway, and collision avoidance will be measured using a driving simulator, a car surrounded by viewing screens that immerse drivers in a virtual reality driving environment. We will compare the way that driving changes with the complexity of a cognitive task with the way it changes as tracking load increases (the number of vehicles tracked at once). We will also determine if these effects are stronger when the driver experiences real motion, which stimulates both the vestibular and somatosensory systems, as compared to when the driver is static. This is important to learning how attention is shared between vision and the vestibular and somatosensory systems during coordinated action in young and older adults. Such information is critical to understanding falls, which are a serious health-risk in older adults. Given that we will be investigating driving, this research will also provide information useful in reducing automobile collisions, a leading cause of injury and death in Canada. Collisions can occur at any age but older adults are more likely to die or sustain serious injury as result. If driving involves multiple-object tracking, then multiple-object tracking training may reduce collision risk for older adults.