Fig. 1

The stimuli and procedure used in Experiment 1. All N items were initially stationary for 0.5 × N s then started to move. The target would change its identity (T↔L) at a time randomly selected from 0.3 to 6.0 s. Os were asked to respond as soon as they detected the target. Once a response was made, all items would be replaced by empty circles and Os would use the mouse to indicate the prior location of the target. A trial would be terminated if Os did not make a response within 2 s after the change