Which memory type is preserved in H.M., despite impairment in declarative memory?

• A. Procedural memory (motor skill learning)
• B. Episodic memory
• C. Semantic memory
• D. Working memory

Answer: (A)

Procedural memory is preserved in H.M. because the brain systems that support nondeclarative, skill-based learning rely on structures like the basal ganglia and cerebellum, not the hippocampus. H.M. could improve on motor tasks and other procedures with practice even though he could not form new declarative memories about experiences or facts. This shows that knowing how to do something (procedural memory) can stay intact when explicit memory for events and facts (episodic and semantic memory) is severely impaired by hippocampal damage. Working memory is a separate short-term system, and while HM had significant declarative memory impairment, the standout preserved ability in his case is procedural memory.