Fig. 2

Behavior. a An example trajectory. The initial direction of the reach (green) starts toward the expected direction of the target, given the current hand position. It later moves in the actual direction of the target. The inset shows an enlarged view of the beginning of the reach. b The median bias of the trajectory over time. A bias of 1 signifies that the direction of the trajectory is toward the expected target direction, while a bias of 0 signifies that the direction of the trajectory is toward the actual target direction. Negative biases signify movement away from the expected direction. Different traces are shown for hand positions at varying distances from the center of the workspace. Error bars are standard errors of the median. c The mean latency of reaches as a function of the angular difference between the actual and expected target directions. d The difference in mean latency between expected and unexpected reaches (expected minus unexpected), depending on the hand’s distance from the center. “Expected” reaches are those that had an angular difference between the actual and expected target directions of less than 60°. “Unexpected” reaches had an angular difference of more than 120°. In panels c and d, error bars represent SEMs. In panels b and d, distances from the center are divided as follows: “closest” is 0–20% of distances from the center, “mid-close” is 20–40%, “mid-far” is 40–60%, and “farthest” is 60–100%. We used these divisions for plotting, rather than standard quartiles, to ensure that there were “unexpected” reaches in each bin. When using standard quartiles, there were no “unexpected” reaches for some monkeys in the last quartile (greatest 25% of distances from the center) because when very far from the center, the next target cannot be in an unexpected direction (farther away from the center)