Exploratory noise governs both flexibility and spontaneous errors and is regulated by cocaine

SUMMARY In many cognitive processes, lapses (spontaneous errors) are attributed to nuisance processes like sensorimotor noise or disengagement. However, some lapses could also be caused by exploratory noise: behavioral randomness that facilitates learning in changing environments. If so, strategic processes would need only up-regulate (rather than generate) exploration to adapt to a changing environment. This view predicts that lapse rates should be correlated with flexibility because they share a common cause. We report that when macaques performed a set-shifting task, lapse rates were negatively correlated with perseverative error frequency. Furthermore, chronic exposure to cocaine, which impairs cognitive flexibility, increased perseverative errors, but, surprisingly, improved overall performance by reducing lapse rates. We reconcile these results with a model in which cocaine decreased exploration by deepening attractor basins corresponding to rules. These results support the idea that exploratory noise contributes to lapses, meaning that it affects rule-based decision-making even when it has no strategic value.