Figure 1.

Attentional state was controlled with a multi-object tracking task. Animals initiated trials by fixating a central point. Four identical Gabor stimuli then appeared, and one or two of them were cued as targets with a brief elevation in luminance. The monkey then maintained fixation while attentively tracking the targets as they moved along independent randomized trajectories that brought one of the stimuli into the receptive field, at which point all four stimuli paused for 1000 ms. The stimuli then shuffled position a second time, with randomized trajectories that placed them at equally eccentric positions outside the receptive field. The fixation point then disappeared, indicating that the monkey should saccade to the previously cued targets. Juice reward was delivered if the monkey correctly made a saccade to each cued stimulus and none of the distracter stimuli.