Types of long-term memory

• Memories in the semantic memory store are not 'time-stamped'.
• Endel Tulving proposed the idea that there are three LTM stores: episodic memory, semantic memory, and procedural memory.
• Memories in the episodic memory store are 'time-stamped' and include several elements such as places, people, objects and behaviour.
• Episodic memory is memory store of personal events. It includes context and involves the recollection of visual imagery as well as the feeling of familiarity.
• Procedural memory is the type of long-term memory that involves remembering how to perform certain actions, skills, and tasks. It is hard to explain in words.
• Long-term memories are formed through a process called consolidation, which involves the transfer of information from short-term memory to long-term memory.
• Semantic memory is the type of long-term memory that involves remembering general knowledge, concepts, and facts that are not tied to a specific personal experience.
• Cohen and Squire(1980) disagree with the division of the LTM into three types, arguing that episodic and semantic memories are stored together in one LTM store (declarative memory).
• Semantic and episodic memory are described as declarative or explicit memory because they have to consciously be recalled.
• Procedural memory is a type of implicit or non-declarative memory that is not consciously recalled.
• A strength of Tulving’s proposal of types of LTM is that there is clinical evidence from case studies of HM and Clive Wearing. Their episodic memory was severely impaired due to amnesia. They struggle recalling past events but their semantic memory was somewhat unaffected e.g. they still understood the meaning of words. Their procedural memories were also intact e.g they could walk, talk and in Wearing’s case play the piano. This evidence supports Tulving’s view that LTM is not unitary, different types exist and are stored in separate brain areas as when one store is damaged the others are unaffected.
• A strength of Tulving’s view of different types of LTM is the neuroimaging evidence supporting it. There is evidence from brain scan studies that the different types of LTM are stored in different parts of the brain. Tulving et al got their participants to complete memory tasks as their brains were being scanned using a PET scanner. It showed that episodic and semantic memories were both recalled from an area called the prefrontal cortex which is divided into two: left hemisphere - semantic memories, right hemisphere - episodic memories. This scientific evidence strengthens Tulving’s view that there are separate LTM stores.
• A weakness of Tulving's view is that Cohen and Squire disagreed with Tulving’s idea that episodic and semantic memory are separate systems. Instead, they argued episodic and semantic memory are part of one type of memory system called “declarative memory”, because both involve conscious recall. They suggested that semantic memories often develop out of episodic experiences. For example, knowledge about a historical event (semantic) may have first been learned during a specific lesson (episodic). This overlap indicates that the boundaries between episodic and semantic memory are not always distinct, as Tulving claimed. This weakens Tulving's theory as it may oversimplify the structure of memory, reducing its explanatory power.