Subitizing, counting, and multiple-object tracking: constraints on item individuation as they affect participants of different ages

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The objective for this research is to find out how the ability to monitor several visual objects at once develops and changes from childhood to old age. I will use two different tasks: the enumeration task, in which observers say how many items there are as fast as they can with accuracy, and the multiple-object tracking task, in which observers keep track of the positions of a number of items as they move among other items. Although these tasks seem very different, they both involve the ability to be aware of a number of distinct entities at a time. Enumeration is important insofar as the ability to "know at a glance" the number of items is fundamental to the development of the number concept in children. Math disabilities are as prevalent as reading disabilities and yet little is known about them. However, recent studies suggest a link between problems in basic enumeration skills and the development of more pervasive mathematical disabilities. Multiple-object tracking involves item movement, and as such, is fundamental to visual-motor coordination. For example, driving through a busy intersection requires tracking positions of pedestrians, cyclists, and cars. Understanding age-related change in multiple-object tracking may help explain why older drivers are disproportionately at risk at intersections. For example, Preusser et  al. (1998) showed that drivers aged 65-69 years were 2.26 times more at risk at intersections than other drivers, while only 1.29 times more at risk for other types of crash. Drivers 85 years and older were 10.62 times more at risk at intersections as compared to 3.74 for other types of crash. Consequently, research on multiple-object tracking may benefit Canada insofar as it may be used to reduce the number of vehicle crashes involving older drivers (a growing segment of the driving population). Overall, the results of these studies will be important for basic research on visual attention and lifespan development. As well, because understanding disorders requires information about normal functioning for the affected age groups, this information may be useful for practitioners treating individuals with attention-related disorders, such as Attention Deficit Disorder, autism, Alzheimer's Disease, schizophrenia, and neglect.