– In 1985 Endel Tulving realised that the MSM’s view of LTM was too simplistic and inflexible.
– He proposed that there are three different LTM stores, containing different types of information.
– He also divided these into two main types of memory: explicit or implicit memory
– This is the distinction between knowing about and knowing how
– Episodic and semantic memories are examples of knowing about
– Procedural memories are knowing how
EPISODIC MEMORY
– Knowing about not how
– Refers to our ability to recall events from our lives.
– These types of memory are concerned with your personal experiences eg. First day of school, birthdays
– These memories are time-stamped and include several elements, such as people and places, objects and behaviours and even the context and emotions surrounding the events
– You also have to make a conscious effort to recall them.
– Therefore, episodic memories have three elements: The details of the event, the context and the emotions
SEMANTIC MEMORY
– Knowing about not how
– This store contains out knowledge of the world.
– For example, the taste of a certain food and the meaning of words.
– Semantic memories begin as episodic memories as we learn based on personal experiences
– Then there is a gradual transition from episodic to semantic memory when the memory slowly loses its association to particular events
– These memories are not time-stamped (However, some people still have a strong recollection of where and when they learned the information)
– It contains an immense collection of material which is constantly being added to.
PROCEDURAL MEMORY
– Knowing how not about
– Our memory for actions, skills or how we do things.
– Eg. Riding a bike or tying a shoelace
– Remembering how to do something rather than knowing the rules if what to do
– We can recall these memories without conscious awareness or a great deal of effort.
– For example, driving a car.
– These memories are acquired through repetition and practice
– We are less aware of these memories as they are automatic
– It is important that they are automatic so we can focus our attention on other tasks while performing these skills
EVALUATION OF THE TYPES OF LONG TERM MEMORY
STRENGTHS
Research Support
– The case studies of HM and Clive Wearing both support the idea of different stores of LTM.
– Episodic memory and forming new long term memories in both men was severely impaired as a consequence of amnesia.
– They had great difficulty recalling events that had happened to them after getting amnesia but their semantic memories are relatively unaffected. For example, they still understood the meaning of words.
– So HM won’t remember watching the TV half an hour ago but he won’t need the concept of a TV explained to over and over again and they both knew how to tie their shoelaces, walk and speak
– Clive Wearing knew how to read music, sing and play the piano.
– They could not form new episodic LTMs but their semantic and procedural memories were working fine
– This means that not only are these types of memory different but the different types of LTM are also stored in different parts of the brain.
Neuroimaging evidence
– In 1994 Tulving got their participants to perform various memory tasks while their brains were scanned using a PET scanner.
– They found that episodic and semantic memories were both recalled from an area of the brain known as the prefrontal cortex.
– This area is divided in two, one on each hemisphere of the brain.
– The left prefrontal cortex was involved in recalling semantic memories and episodic memories were recalled from the right prefrontal cortex.
– This is a strength because 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
LIMITATIONS
Problems with Evidence
– It is difficult to reach a firm conclusion by studying brain damaged patients.
– There are problems of evidence from brain damaged patients.
– In addition, the difficulty with studies of amnesiacs, including HM, is that it is difficult to be certain of the exact parts of the brain that have been affected until the patient has died.
– Most of these studies are conducted with living patients and it is hard to tell what has been affected without doing a post-mortem (after death)
– Damage to a particular area of the brain does not necessarily mean that the area is responsible for a particular behaviour, it may be acting as a relay station.
– Malfunction of the relay station would impair the performance.
– This means we cannot establish a causal relationship between a particular brain region and type of long-term memory.
Problems with Clinical Evidence
– Clinical studies involve people who have had brain injuries, usually due to an accident and these are unexpected.
– The researcher has no control over what happened to the patient/participant before they experienced the injury.
– For example, in the case of amnesia, the psychologist will have very little idea of what the patient’s memory was like before the injury.
– Therefore, they won’t know how much worse it is now than it was then.
– If the patient achieves a digit span of just three items on a test of STM capacity they wouldn’t know if it was worse or the same before the injury.
– This means it is hard to know what has caused the amnesia – the injury to a certain part of the brain, or other variables that could not be controlled
– Therefore, the conclusions researchers have reached about memory, based on clinical studies, may not be valid.