Tulving (1989) carried out a study to investigate the distinction between episodic and semantic memory.
His method was injecting a small dose of radioactive gold into the bloodstream of the participant, including himself. Participants were then instructed to think about personal events or general knowledge (e.g. history of psychology). He then recorded the blood flow in different areas of the brain.
He found that episodic memory associated with a high level of activation in the frontal cortex. This is when the participant was thinking about personal events. Also, semantic memory associated with a high level of activation in the posterior or back regions of the cortex. This is when the participant was thinking about facts.
He then concluded that evidence supports his view that there are separate long memory systems.
Furthermore, Yarnell and Lynch (1970) investigated the effects of conclusion on memory loss.
Their method was a field study of American footballers that had been concussed during a game. After regaining consciousness, they were asked about the game just before the trauma. They were asked again between 3 and 20 minutes later.
They found that accurate information was given immediately. And that between 3 and 20 minutes later, no information could be given.
The conclusion was that the trauma has disrupted the process of finding a memory (consolidating a memory trace). It...