MEMORY: types of long term memory

AO1

LTM is divided into two main types: explicit/ declarative memory and implicit/ procedural memory.

Distinction between knowing THAT and knowing HOW.

Episodic and semantic memories are examples of knowing THAT - explicit/ declarative memories.

procedural memories = knowing how to do things

declarative memories = knowledge of the information

Episodic memory

• are about knowing THAT

• this kind of memory is concerned with your personal experiences, e.g. recollection of your first day at school, a family holiday etc - episodic/ events

• may also recall associated emotions felt at the time of the episode -

• episodic memories have three elements - specific details of the event, the context and the emotions.

Semantic memory

also about knowing THAT, but instead of knowing the first day at school was scary, you also know that people of a certain ge go to school and that 2+2=4 and the capital of England is London

• knowledge about the world which is shared by everyone rather than personal experiences

• may relate to functions, social norms, appropriate behaviour

• generally begin as episodic memories because we acquire knowledge from personal experiences

Procedural memory

• concerned with skills, such as playing the piano, knowing how to dive, how to read etc.

• Remembering how to do something rather than knowing the rules of what to do

• typically acquired though repetition and practice, unlike episodic and semantic memory, this kind of memory is IMPLICIT (without consciously thinking of them)

• they become automatic so we are less aware of them

• when thinking too much about the procedural memories this can inhibit our ability to perform them well - this attention to the step by step process disrupts the well learned, automatic performance

• it is important that procedural memories are automatic so we can focus our attention on other tasks while performing these everyday skills

AO3 - evidence of brain scans

the distinction made between the three kinds of LTM is supported by the brain scan research

episodic memory is associated with the hippocampus and other parts of the temporal lobe where the hippocampus is located, as well as with activity in the frontal lobe. Semantic memory also relies on the temporal lobe.

procedural memory activation is associated with the cerebellum, which is involved in the control of fine motor skills as well as the motor cortex. The basil ganglia and limbic system are also involved in this kind of learning.

brain scans therefore indicate that three types of memory are found in different parts of the brain and so are separate

AO3 - distinguishing procedural and declarative memories

evidence from case studies offers further support for different types of LTM

The case study of HM - his ability to form new LTMs was affected by the destruction of his hippocampus (parts of his temporal lobes were destroyed) but he retained his pre-existing LTMs.

After the surgery, HM could still form new procedural memories but not episodic or semantic memories. For example, he was able to to learn how to draw a figure by looking at its reflection in a mirror, a skill called mirror drawing - this is a procedural memory. However he had no memory THAT he had learned this (episodic/ semantic memory)

this supports the distinction between procedural and declarative memories, and hence the existence of multiple types of LTM

AO3 - problems withe evidence from patients with brain damage

It is difficult to reach a firm conclusion studying brain damaged patients

Same difficulty with brain damaged patients from WMM apply here too - in addition, the difficulty with study on amnesiacs, including HM, is that it is difficult to be certain of the exact parts of the brain that have been affected until a patient has died. Most studies are conducted with living patients. Damage to a particular area of the brain does nor necessarily mean that area is responsible for a particular behaviour - it may be acting as a relay station. Malfunction of the relay station would impair performance

this means that we cannot establish a casual relationship between a particular brain region and type of LTM.

AO3 - distinguishing episodic and semantic memories

further support for different types of LTM comes from studies of patients with Alzheimers

researchers have sought to examine the relationship between episodic and semantic memories by studying patients with Alzheimers disease and found some paitents who retain the ability form new semantic memories but not episodic memories. this is a single dissociation i.e separation between two abilities. a second dissociation was found by Irish et al in Alzheimers patents who have the reverse - poor semantic memories but generally intact episodic memories

this double dislocation suggests that episodic and semantic memories are separate, and that episodic memories may be a gateway to semantic memory, but it is possible for semantic memories to form separately.

AO3 - case study support

One strength of the types of LTM comes from clinical evidence. For example, the case of HM (Henry Molaison), who had parts of his hippocampus removed to treat epilepsy, provides strong support for the distinction between different types of LTM. After the surgery, HM could no longer form new episodic or semantic memories, but he retained his procedural memory, such as learning to draw a figure by looking in a mirror. This supports the view that different types of LTM are stored in different brain areas.

Further support comes from neuroimaging studies. Brain scans show that different types of LTM are associated with activity in different areas of the brain. For example, Tulving et al. (1994) found that episodic and semantic memories are stored in different parts of the prefrontal cortex. This biological evidence increases the validity of the theory.

AO3 - case study use

Additionally, most research into LTM types is based on case studies, such as HM or Clive Wearing. While these provide valuable insight, they are based on individuals with unique brain damage and may not be generalizable to the wider population. This reduces the external validity of the findings.