Memory: Types of LTM
Key Terms
Episodic Memory – A long term memory store for personal events. It includes memories of when the events occurred 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.
PET scan – Positron Emission Tomography. A brain-scanning technique used to study activity in the brain. Radioactive glucose is ingested and can be detected in the active areas of the brain.
Hemispheres – The forebrain (largest part of brain) is divided into two halves or hemispheres.
Control Group – In an experiment with an independent groups design the control group is a group of participants who receive no treatment. Their behaviour acts as a baseline against which the effect of the independent variable may be measured.
Declarative Memory – Memories that are consciously recalled, explicit and can be put into words.
Introduction
Endel Tulving (1985) was one of the first psychologists to realise that there were 3 types of LTM and the Multi-store model was too simplistic and inflexible to demonstrate this. He named them episodic, semantic and procedural.
Episodic Memory
This refers to our ability to recall events/episodes from our lives, like a record of daily happenings. Examples of this include your last family holiday, the last wedding you went to, what you had for dinner last night, or that dentist appointment you went to last month (etc…).
All of these episodic memories are ‘time-stamped’ – you can recall when they happened. In addition to this, you’ll remember key details and elements of the event, such as who was there, the location of the event, behaviours you observed or what objects where present. Lastly, you have to make a conscious effort to remember episodic memories. You may be able to do so quickly, but you are still aware you have to search for it.
Semantic Memory
This store contains our knowledge of the world. This includes facts but in the broadest possible sense. Examples of this includes the taste of an orange, applying to university and meaning of words (this last one is very important). It also contains knowledge of a vast range of concepts such as love.
These memories are not ‘time-stamped’ like episodic memory is, and is less personal containing facts we all share. However, it is constantly being added to and is an immense collection of material.
Procedural Memory
This is our memory for actions, skills, or basically how we do things. We can recall these without conscious awareness or a great deal or effort. These are the types of skills we might find it hard to explain to someone else. Such as driving a car. If you try to describe it, the task itself may become more difficult.
AO3 Evaluation: Clinical Evidence
The famous case studies of Henry Molaison and Clive Wearing are relevant here. Both had severely impaired episodic memory, they had great difficulty recalling events, but there semantic memory were relatively unaffected as well as their procedural.
This evidence supports Tulving’s view that there are different types of LTM. One store can be damaged but other stores are left intact. This is clear evidence that not only are these types of memories different, but they are stored in different parts of the brain.
Neuroimaging Evidence
Tulving et al (1994) got ps to perform memory tasks whilst having a PET scan. They found that episodic and semantic memories were both recalled from the prefrontal cortex. This area is divided into two hemispheres of the brain, the left was semantic and the right was episodic.
The strength of this finding is that it supports the view that there is a physical reality to the different types of LTM within the brain. It has also been confirmed many times in later research studies, further supporting the validity of this finding.
Real-Life Application
The benefit of being able to distinguish between types of LTM is that it enables scientific treatments to be developed. For instance, Belleville et al. (2006) demonstrated that episodic memory could be improved in older people who had a mild cognitive impairment. The trained ps performed better on a test of episodic memory after training than a control group.
Problems with Clinical Evidence
By studying people with brain injuries like Clive Wearing and Henry Molaison has provided psychologists with a lot of useful information about what happens when memory is damaged. However, such clinical evidence is not perfect. For instance, there is a serious lack of control of all sorts of different variables in clinical studies.
Three types of LTM or Two?
Cohen and Squire (1980) disagree with Tulving’s division of LTM into three types. They accept that procedural memories represent one type of LTM. However argue that semantic and episodic memories are stored together in one LTM store that they call Declarative Memory.
