What characterizes a dissociation in neuropsychology?

• A. One task impaired while another is normal in the same patient
• B. Both tasks impaired in the same patient
• C. All tasks are normal in the patient
• D. All tasks are impaired in a patient

Answer: (A)

A dissociation shows that two cognitive processes can operate independently. It happens when a patient performs poorly on one task while another task, relying on different processes, remains normal. This pattern implies separate neural systems support the two abilities. For example, someone might have trouble naming objects but can recognize them or pick the correct object when shown pictures—demonstrating a dissociation between naming (language production) and recognition (perception). If both tasks were impaired in the same patient, that would suggest a more general or shared deficit, not a dissociation.