Figure 2.

Behavioral results in the PCL task. A, B, Percentage correct responses increased (A) and reaction times decreased (B) similarly in the stress and control groups across training, indicating successful classification learning in both groups. C, Although stress did not affect participants' learning curves in the PCL task, it reduced declarative knowledge about the task. D, Furthermore, stress changed the strategies used during classification learning: stressed participants, compared with nonstressed controls, significantly more often used complex strategies associated with the procedural system and significantly less often used simple strategies associated with the declarative system. Asterisks indicate significant differences between the stress and control groups (p < 0.05). Data represent mean ± SEM.