Figure 4.

Test of whether directional cues were being used to choose pursuit targets based on their spatial location. Time vectors of horizontal and vertical eye velocity have been plotted in a way that shows the trajectory of eye velocity in two dimensions. Time is represented by the symbols on the traces: filled circles, open circles, and open triangles show moments 150, 200, and 250 ms after the onset of target motion. Traces are as follows: black, responses in experiments in which the spatial location of the target could be determined by the directional cue; red, responses when the cue contained no overall motion; blue, responses in experiments in which the spatial location of the target was uncertain and was not knowable from the directional cue. Data are from subject 3. Experiments with uncertain target locations were run before those with certain target locations.