In which of the following examples of two different brain-injured patients (Tom and Tim) is a double dissociation demonstrated?
A) Both Tom and Tim have good episodic memory but poor semantic memory.
B) Tom and Tim both show deficits in episodic and semantic memory.
C) Tom has good semantic memory and poor episodic memory, while Tim has good episodic memory but poor semantic memory.
D) Both Tom and Tim have good semantic memory but poor episodic memory.

Question

Quizplus · Accepted Answer

C is the correct choice because a double dissociation is demonstrated by showing that patients have opposite patterns of performance on two tasks. In this case, Tom shows good semantic memory but poor episodic memory, while Tim shows good episodic memory but poor semantic memory. This suggests that these two types of memory rely on separate neural mechanisms, since one patient can perform well on one task but poorly on the other. The other answer choices do not demonstrate a double dissociation because they do not show opposite patterns of performance on two tasks.

In Which of the Following Examples of Two Different Brain-Injured