Task performance in all four groups.

<p>(<b>a</b>) Accuracy was lower in trials with novel sounds in comparison to those with standard sounds in all four groups (*, p<0.005). Notice the inverted-U shape of accuracy in the two trial types for the four groups arranged in the panel according to their levels of PFC-Striatum DA balance. (<b>b</b>) Response times in standard and novel trials (*, p<0.03). Notice that two groups displayed similar RT (i.e., ValA1- and MetA1+) in standard and novel trials, whereas the other two groups (i.e., ValA1+ and MetA1-) showed larger RT in novel than in standard trials. (<b>c</b>) Distribution of mean accuracy and RT slowing in all single individuals. Notice that the black symbols, representing individuals in the balanced groups, are mainly distributed on the upper right part of the plot, showing larger RT slowing after novel relative to standard sounds, but better mean accuracy than the unbalanced groups. In contrast, individuals from the unbalanced groups (white symbols) were distributed on the lower part of the graph as their accuracy was slightly worse, and along the Y axis because their RTs were not delayed by the novel sounds.