Where What You Count is What Really Counts

We noticed that human subjects were notably faster and more accurate in concurrent counting of three location-based events while they ignored the identity of targets, compared to concurrent counting of three identity-based events while they ignored the locations. In a control experiment, subjects performed a location-based triple counting task, while now also paying attention to the target identity. This did not incur any additional cost, compared to the cost of the location-based counting. Performing each of these tasks relies on maintaining three running numerical counters, and on switching between them to increase each one. Our results suggest that switching between these counters has lower cost when they are associated to spatial locations, compared to when they are associated to identities. This difference is not affected when additionally processing the identity of items. We argue that this might be related to the advantage of the space in switching attention between internal representations.