The trajectories show the population neuronal activity when down-left targets of varying value were chosen. The average population response for a given condition and time period (10 ms) is represented as a point in state space. Responses are shown from 200 ms before to 10 after saccade onset. The time of saccade initiation is indicated by the larger dot. The trajectories are grouped according to both chosen and non-chosen values. The red, orange and blue colors indicate the large (L), medium (M), and small (S) chosen values in choice trials. Solid, dash, and dotted lines indicate the small, medium, and large non-chosen values, repectively. There are fewer trajectories when the chosen target was less valuable, because it was chosen less often. The trajectories for choice trials were influenced by both chosen and non-chosen values. Specifically, given a chosen value (indicating by color), the trajectories were slightly lower along the value axis if the non-chosen value was larger (indicating by line patterns). Thus, the neuronal population as a whole represents a relative action value signal. For comparison, purple, black, and green colors indicate the large, medium, and small chosen value in no-choice trials, repectively. If no-choice trials simply represent a situation that is similar to the choice trials, but in which the non-chosen value is simply zero, the trajectories for no-choice trial should be similar to the ones on choice trials with small non-chosen value. However, that is not the case. Instead, the trajectories for no-choice trials always reach an end point that is less extended along both the value and direction axis than the respective trajectories for choice trials. Thus, the neural population responds differently on choice and no-choice trials. SEF, supplementary eye field.