Final answer:
Individuals with retrograde amnesia due to organic causes like brain trauma typically retain procedural memories while struggling with episodic and semantic memories.
Step-by-step explanation:
Retrograde amnesia is a condition where individuals are unable to recall past memories before the onset of amnesia. The causes for this type of amnesia can vary, but when it is due to organic causes, such as physical trauma to the brain, sufferers typically retain procedural memories while they may struggle with episodic and semantic memories. Procedural memory involves the recall of skills and how to perform tasks, which usually remain intact. Meanwhile, episodic memory, which deals with personal experiences and specific events, and semantic memory, which involves facts and general knowledge, are often affected by retrograde amnesia caused by organic factors like a brain injury.
Illustrative cases such as the famous patient H. M. show that while episodic and semantic memories can be severely impaired due to brain damage, procedural memories can sometimes be spared. Therefore, H. M. could become more proficient at solving puzzles over repeated attempts, despite not recalling previous encounters with the puzzle. This distinction between memory types is crucial in understanding what sufferers of retrograde amnesia due to organic causes will typically remember.