“System 2 (the controlled system) is our slower process of conscious analysis and reasoning. It’s the part of thinking that considers choices, makes decisions, and exerts self-control. We also use it to train System 1 to recognize and respond to particular situations that demand reflexive action. The running back is using System 2 when he walks through the moves in his playbook. The cop is using it when he practices taking a gun from a shooter. The neurosurgeon is using it when he rehearses his repair of the torn sinus.”