Types of long term memory (LTM)

Episodic memory

A long term memory store for personal events, It includes memories of when the events occured and of the people, objects places and behaviours involved. Memories from this store have to be retrieved consciously and with effort

Semantic memory

A long term memory store for our knowledge of the world. This includes facts and our knowledge of what words and concepts mean. These memories usually also need to be recalled deliberately

Procedural memory

A long term memory store for our knowledge of how to do things. This includes our memories of learned skills. We usually recall these memories without making a conscious or deliberate effort.

Clinical evidence

Case studies of HM and Clive Wearing show that brain damage can severely impair episodic memory while leaving semantic and procedural memories intact. Both men still understood word meanings and retained skills like walking, speaking, or playing the piano (Wearing). This supports Tulving's view that different memory stores exist within LTM, as one can be damaged while others remain completely functional.

Counterpoint : However, clinical studies of brain-injured patients lack control over variables. Researchers have no way of controlling what happened to the patient before or during the injury, and have no data on their memory capacity prior to the damage. This lack of control limits what these case studies can confidently conclude about how normal LTM operates.

Conflicting neuroimaging evidence

There is an active disagreement in research regarding the exact physical locations of LTM types in the brain. Buckner and Petersen (1996) concluded that semantic memory is on the left side of the prefrontal cortex and episodic is on the right. Conversely, Tulving et al. (1994) linked the left prefrontal cortex with encoding episodic memories and the right side with retrieving them. This poor agreement directly challenges neurophysiological claims about clear-cut brain localization.

Real world application

Understanding distinct LTM types allows psychologists to target specific memory problems, particularly age-related memory loss which primarily impacts episodic memories (making recent personal events harder to recall). Belleville et al. (2006) created a specialized training intervention that significantly improved episodic memory in older adults compared to a control group. This proves that separating the types of LTM has practical benefits for medical treatments.