However, no jump events occurred KRX 0401 in this or later phases of the experiment. The second phase consisted of ten further delivery trials. However, here, at the onset of each trial, the participant was required to choose between two packages (Figure 5). The location of the truck and the house was chosen randomly. The location of one package, designated subgoal one, was randomly positioned along an ellipse with the truck and house as its foci and a major-to-minor axis ratio of 5/3. The position of the other package, subgoal two, was randomly chosen, subject to the constraint

that it fall at least 100 pixels from each of the other icons. At the onset of each trial, each package would be highlighted with a change of color, twice (in alternation Trametinib clinical trial with the other package), for a period of 1.5 s. Highlighting order was counterbalanced across trials. During this period the participant was required to press a key to indicate his or her preferred package

when that package was highlighted. After the key press, the chosen subgoal would change to a new color. At the end of the choice period, the unchosen subgoal was removed, and participants were expected to initiate the delivery task. The remainder of each trial proceeded as in phase one. The third and main phase of the experiment included 100 trials. One-third of these, interleaved in random order with the rest, followed the profile of phase two trials. The remaining trials began as in phase

two but terminated immediately following the package-choice period. To determine the influence of goal and subgoal distance on package choice, we conducted a logistic regression on the choice data from phase three. Regressors included (1) the ratio of the distances from the truck to subgoal one and subgoal two, and (2) the ratio of the distances from the truck to the house through subgoal one and subgoal two. To test for significance across subjects, we carried out a two-tailed t test on the population of regression coefficients. To further characterize the results, we fitted two RL models to each participant’s phase-three see more choice data. One model assigned primary reward only to goal attainment and so was indifferent to subgoal distance per se. A second model assigned primary reward to the subgoal as well to the goal. Value in the first case was a discounted number of steps to the goal, and in the second case it was a sum of discounted number of steps to the subgoal and to the goal. Choice was modeled using a softmax function, including a free inverse temperature parameter. The fmincon function in MATLAB was employed to fit discount factor and inverse temperature parameters for both models and reward magnitude for subgoal attainment for the second model. We then compared the fits of the two models calculating Bayes factor for each participant and performing a two-tailed t test on the factors.