Figure 2.

A, The evolution of mean decision times (and mean SPD), in slow (blue) and fast (red) blocks, over the course of training for Monkey S (left) and Monkey Z (right). Each bin represents the average decision time (and success probability) calculated across 5000 trials performed in either the fast or the slow blocks. The gray shaded area illustrates the period in training when each monkey's behavior is clearly and consistently different in the two blocks. Thin solid arrows indicate four specific times over the course of training, which will be examined in more detail later. B, Example sessions for each monkey, showing the decision times and success probability at decision for sequential trials in a slow block (blue), a subsequent fast block (red), and another slow block (blue). C, Distributions of decision times, and cumulative distributions of success probability at decision time for easy (blue), ambiguous (green) and misleading (red) trials in the slow (top) and fast (bottom) blocks for Monkey S (left) and Monkey Z (right). The vertical dotted lines mark mean values and shaded distributions of decision time illustrate error trials.