Types Of Long-term Memory Flashcards
Types of long-term memory
Endel Tulving (1985) was one of the first cognitive psychologists to realise that the multi-store models view of long-term memory was too simplistic and inflexible. Tulving proposed that there are in fact three LTM stores, containing quite different types of information. He called them episodic memory, semantic memory and procedural memory.
Episodic memory
Refers to our ability to recall events (episodes) from our lives. This has been likened to a diary, a record of daily personal experiences. Some examples are: your most recent visit to a dentist, a gig you went to last week. These memories are complex.
First of all, they are ‘time-stamped’- in other words you remember when they happened as well as what happened. Episodic memories also store information about own events relative to each other in time.
Second, your memory of a single episode will include several elements, such as people and places, objects and behaviours. All of these memories are interwoven to produce a single memory. Third, you have to make a conscious effort to recall episodic memories. You do this quickly, but you are still aware that you are searching for your memory of what happened when you went to the dentist.
Semantic memory
This store contains our shared knowledge of the world. It has been likened to a combination of an encyclopaedia and a dictionary. So it includes knowledge of such things as: how to apply to university, what an orange tastes like, what zombies like for dinner and the meaning of words. This last one is important. Your semantic memory contains knowledge of an impressive number of concepts such as ‘animals’, ‘love’ and ‘frozen’.
These memories are not ‘time-stamped’. We don’t usually remember when we first heard about the new frozen film, for example. Semantic knowledge is less personal and more about facts we all share. It contains an immense collection of material which, given its nature, is constantly being added. According to Tulving, it is less vulnerable to distortion and forgetting than episodic memory.
Procedural memory
This is our memory for actions or skills, or basically how we do things. We can recall these memories without conscious awareness or much effort (eventually). A good example is driving a car. Our ability to do this become automatic through practice. We change gear without having to recall how. We indicate left or right without even realising we’ve done so.
These are the sorts of skills we might even find quite hard to explain to someone else.
Strength-clinical evidence
Evidence from the famous case studies of HM (Henry Molaison) and Clive Wearing. Episodic memory in both men was severely impaired due to brain damage (caused by an operation and infection respectively). But their semantic memories were relatively unaffected. They still understood the meaning of words. For example, HM could not recall stroking a dog half an hour earlier but he did not need to have the concept of ‘dog’ explained to him. Their procedural memories were also intact. They both still knew how to walk and speak, and Clive Wearing (a professional musician) knew how to read music, sing and play piano. This evidence supports Tulvings view that there are different memory stores in LTM-one store can be damaged but other stores are unaffected.
Counterpoint- studying people with brain injuries can help researchers to understand how memory is supposed to work normally. But clinical studies are not perfect. A major limitation is that they lack control of variables. The brain injuries experienced by participants were usually unexpected. The researchers had no way of controlling what happened to the participant before or during the injury. The researcher had no knowledge of the individuals memory before the damage. Without this, it is difficult to judge exactly how much worse it is afterwards.
This lack of control limits what clinical studies can tell us about different types of LTM.
Limitation-conflicting neuroimaging evidence
Conflicting research findings linking types of LTM to areas of the brain. For example Randy Buckner and Steven Petersen (1996) reviewed evidence regarding the location of semantic and episodic memory. They concluded that semantic memory is located in the left side of the prefrontal cortex and episodic memory on the right. However, other research links the left prefrontal cortex with episodic retrieval (Tulving et al. 1994).
This challenges any neurophysiological evidence to support types of memory.
Strength-real world application
Understanding types of LTM allows psychologists to help people with memory problems. For example, as people age, they experience memory loss. But research has shown this seems to be specific to episodic memory- it becomes harder to recall memories of personal events/experiences that occurred relatively recently though past episodic memories remain intact. Sylvie Belleville et al. (2006) devised an intervention to improve episodic memories in older people. The trained participants performed better on a test of episodic memory after training than a control group. This shows that distinguishing between types of LTM enables specific treatments to be developed.
