Abstract
One frequently used task for measuring attentional capacity is multiple object tracking (MOT), where observers attentively track multiple moving target items among a set of identical distractors. MOT performance depends on both the number of targets and their speed (Alvarez & Franconeri, 2007), and therefore provides two measures of attentional capacity: (1) the number of items that can be tracked at a fixed speed, (2) the maximum speed at which a fixed number of items can be tracked. Previously, we showed that 10 days of adaptive MOT training increased performance on both of these measures. Here, we replicate these results, then extend them with the inclusion of (1) an active control group, (2) pre-training and post-training structural and functional neuroimaging measures, and (3) an extensive battery of normed “transfer” tasks, to determine whether improvement in visual attention affects other cognitive domains. Initially, a threshold procedure was used to determine the speed at which subjects could track four targets among twelve distractors. Subjects then completed twenty sessions of MOT practice (90 trials per day), with the object speed on each trial adaptively updated based on the current trial's performance. Over twenty sessions of training, eight subjects increased the speed at which they could reliably track four objects from an initial average of 5.5 deg/s to a final speed of 13.1 deg/s. Additionally, all subjects were able to track additional targets when tested at their initial pre-training speed. In contrast, subjects assigned to the “active control” condition (an adaptive n-back task) did not significantly improve on these MOT metrics. These findings confirm that it is possible to dramatically increase the capacity of visual attention through training, and that training one measure of capacity (increased tracking speed) transfers improvements to a second measure of capacity (increased number of targets).