Many critical tasks such as driving and piloting a plane depend on tracking multiple moving objects with continuously changing positions, speeds, and trajectories. Laboratory studies of multiple object tracking (MOT) require observers to keep track of a small number of moving target objects embedded in a set of identical moving distractors. Surprisingly, these studies show that people can only keep track of about four objects before they begin to make errors. How do people divide their attention between tracked objects while ignoring distractors and why is divided attention limited to four objects? The investigator proposes to study these questions by presenting probe flashes on targets and distractors during MOT and measuring visual attention by recording brain activity using EEG-based measures. Preliminary studies using this approach show that successful tracking performance depends on both enhancement of tracked targets and suppression of distractors. The proposed studies should further reveal why tracking is limited to a small number of objects as well as illuminating why errors occur when attentional capacity is exceeded.
The multiple object tracking (MOT) task captures an important aspect of many critical, real-world tasks such as air-traffic control where errors can have catastrophic consequences. In 2009, there were 1,869 "operational errors" recorded for air traffic controllers including 333 in the serious category. These numbers are considered to be a small fraction of the actual number of errors as the majority go unreported. At least part of the reason for these errors may lie in the limited ability to track more than about four objects. Are there interventions that might improve this critical ability? Importantly, several studies show that the number of tracked objects can be increased through training. For example, it is higher in people who play video games. Conversely, recent reports indicate substantial deficits in the number of objects than can be tracked due to both psychopathology (schizophrenia) and normal aging. Understanding the basic brain mechanisms responsible for these effects is the best approach to ultimately being able to design training methods for improving tracking ability as well as reducing environmental contributions to errors. Finally, from a basic science perspective, understanding MOT should help us understand the mechanisms of visual attention more broadly. Many current theories of attention are based on studies requiring observers to briefly attend to a single stationary location or object. These theories do a poor job of explaining the ability to sustain attention on multiple moving objects for extended periods of time, and this kind of attention may be commonplace in dealing with the dynamic visual world outside of the laboratory.
