Figure 1.

Selective attention task. (A) Examples of the trial sequences for the direction task (upper sequence) and color task (lower sequence). After the monkeys fixated and depressed a lever, a small cue briefly appeared (500 ms), indicating the spatial location of the upcoming target stimulus and the attentional task to be performed. In the direction task, the cue was a small, achromatic moving RDP and instructed the monkey to respond, by releasing the lever, to a change in direction of the cued stimulus (the target). In the color task, the cue was a stationary, colored RDP, instructing the monkey to respond to a change in the color of the target. After cue offset, two moving RDPs were presented at equal eccentricity in opposite visual hemifields, one of them inside the RF of the neuron under study. Changes in the stimuli could occur 500–3550 ms following cue offset. The red circle indicates the spatial focus of attention. Examples of trial sequences in which the target stimulus was the one on the left are not shown here. (B) Target event and three different distractor events in the direction task. The monkeys were only rewarded for responding to a change in the direction of motion of the cued stimulus (top left panel). Trials were terminated without reward if they responded to any of the following distractor types: a change in the color of the cued stimulus (top right, dimension distractor), a change in the direction of motion of the uncued stimulus (bottom left, location distractor), or a change in the color of the uncued stimulus (bottom right, dimension and location distractor). Trials were also terminated without reward if the monkeys missed the target event or broke fixation. Corresponding events were used in the color task.