Amnesia as a Key to Developing Evidential Theories About Memory

Memory has been widely defined as the information that is learned and stored inside of our brains. Attkinson and Shiffron (1968) put forward the initial basic structure of the memory. It included three major stores: the sensory store; short-term store and long-term store in which information is passed through linearly. There are three different established processes by Melton (1963) that allow the retention of a memory within the brain. The first process is encoding, which is where information is gathered, collected and processed in different ways; the main ways being visual, acoustically and semantically. The semantic form refers to the application and association of a memory to a meaning. The secondary process begins in which, the information is stored in the short-term memory, and it stays there for a duration of time – one which varies from individual to individual. If the particular memory is rehearsed, it is transferred into the long-term memory of the brain.

Finally, the last stage is retrieval; where information that is stored within the long-term memory is then retrievable on demand. Contrastingly, Amnesia is a term which refers to a condition in which the memories are not easily retrievable. This inability extends beyond the everyday forgetfulness and shows a failure at a certain point of the memory retention process mentioned beforehand. Amnesia can occur for various different reasons, including neurological causes such as physical injury and psychogenic causes, like mental disorders or post-traumatic stress, even from alcohol abuse known as Korsakoff’s syndrome. This essay will articulate our understanding of the connection between memory and amnesia and the latter shaped the former. As previously stated, the two major storage systems of memory are the short-term and long-term memory. The short-term memory stores information for a more restricted period of time with a quite limited capacity. As opposed to the long-term memory, which stores information for a significantly longer duration with a potentially unlimited capacity. The limit of the capacity of the long-term memory is unmeasurable, as the typical brain stores a vast variety ranging from language, grammar, etiquette, social norms, education as well as personal memories. We understand the immensity more, particularly if we look at an extreme of the spectrum - at individuals with photographic memories, all the information they gather is all stored into their long-term memories for their entire lives.

The other end of this spectrum is represented by those with amnesia who are often unable to retain or collect memory at all. This understanding of memory would not exist in such detail if not for the studies of patients with conditions such as amnesia, which has provided better insight into the functionality of memory. These findings by psychologists have enabled us to divide amnesia into types. The first type of amnesia is referred to as retrograde amnesia, which is the inability to remember or retrieve past memories. The type of amnesia enables us to separate the three processes that aid retention, identify and pinpoint where the brain is failing. This appears to occur within the final process of retention; retrieval. Due to the trauma, instead of the brain to allow access to these particular memories on demand, it fails to locate them leaving those with this condition in varying states. Some have lost only recent memory, from a few weeks to months and some are left without memory going on years. It is interesting to note that these memories are often not lost but rather hidden, and how re-immersing patients into familiar settings can trigger retrieval.

Memory has been widely defined as the information that is learned and stored inside of our brains. Attkinson and Shiffron (1968) put forward the initial basic structure of the memory. It included three major stores: the sensory store; short-term store and long-term store in which information is passed through linearly. There are three different established processes by Melton (1963) that allow the retention of a memory within the brain. The first process is encoding, which is where information is gathered, collected and processed in different ways; the main ways being visual, acoustically and semantically. The semantic form refers to the application and association of a memory to a meaning. The secondary process begins in which, the information is stored in the short-term memory, and it stays there for a duration of time – one which varies from individual to individual. If the particular memory is rehearsed, it is transferred into the long-term memory of the brain.

Finally, the last stage is retrieval; where information that is stored within the long-term memory is then retrievable on demand. Contrastingly, Amnesia is a term which refers to a condition in which the memories are not easily retrievable. This inability extends beyond the everyday forgetfulness and shows a failure at a certain point of the memory retention process mentioned beforehand. Amnesia can occur for various different reasons, including neurological causes such as physical injury and psychogenic causes, like mental disorders or post-traumatic stress, even from alcohol abuse known as Korsakoff’s syndrome. This essay will articulate our understanding of the connection between memory and amnesia and the latter shaped the former. As previously stated, the two major storage systems of memory are the short-term and long-term memory. The short-term memory stores information for a more restricted period of time with a quite limited capacity. As opposed to the long-term memory, which stores information for a significantly longer duration with a potentially unlimited capacity. The limit of the capacity of the long-term memory is unmeasurable, as the typical brain stores a vast variety ranging from language, grammar, etiquette, social norms, education as well as personal memories. We understand the immensity more, particularly if we look at an extreme of the spectrum - at individuals with photographic memories, all the information they gather is all stored into their long-term memories for their entire lives. The other end of this spectrum is represented by those with amnesia who are often unable to retain or collect memory at all. This understanding of memory would not exist in such detail if not for the studies of patients with conditions such as amnesia, which has provided better insight into the functionality of memory. These findings by psychologists have enabled us to divide amnesia into types. The first type of amnesia is referred to as retrograde amnesia, which is the inability to remember or retrieve past memories. The type of amnesia enables us to separate the three processes that aid retention, identify and pinpoint where the brain is failing. This appears to occur within the final process of retention; retrieval. Due to the trauma, instead of the brain to allow access to these particular memories on demand, it fails to locate them leaving those with this condition in varying states.

Some have lost only recent memory, from a few weeks to months and some are left without memory going on years. It is interesting to note that these memories are often not lost but rather hidden, and how re-immersing patients into familiar settings can trigger retrieval. Contrastingly, anterograde amnesia is described as the inability to acquire and retain new information, after the development of amnesia. This type of amnesia represents a breakdown of the established processes of retention starting from the second step, as the brain completely lacks the ability to transfer the information into the long-term memory.

Patients are able to gather information, but this is retained for a significantly shorter period of time, even as short of a few mere seconds. Albeit, this is the worse of the two types as it has no cure, but simultaneously it is the more interesting aspect of amnesia as we are able to explore the other capabilities of the brain. The two main distinctions of long-term memory are a declarative/explicit memory and non-declarative/implicit memory. The former store's information that requires a conscious recollection. This memory can be further divided into two sub-divisions: episodic memory and semantic memory.

Episodic refers to memories of personal experiences including their time and the location of these events. Whilst the semantic memory retains knowledge we have obtained through education such as worldly facts and history. Studies and observations into the sub-divisions by Spiers et al (2001) found that the two were distinctively different. He examined 147 cases of patients with amnesia with damage to the hippocampus area and discovered that there were impairments to episodic memory in all cases, however no substantial damage to the semantic memory. However why this occurs is still being explored. On the other hand, non-declarative memory stores learned skills that can be retrieved unconsciously, allowing individuals to perform actions by rote. This can also be subdivided into two categories: procedural memory and priming. Procedural memory pertains to skills such as riding a bicycle or tying your shoelaces, these motor actions do not require any conscious thought or effort in most cases. Finally, priming refers to how the prior exposure of a stimulus affects the processing of a later stimulus, both of which share a relation.

For example, an individual who is presented with an auditory stimulus of a dog allows a later auditory stimulus of a dog to become easier to recognize, due to their connection. Thus, the first audio would be referred to as the prime, which aids the processing of the audio when presented the second time. Henry Gustav Molaison (1926-2008), familiarly known as H.M was a patient suffering from amnesia, from whom studies were developed that were particularly influential in the development of the understanding of memory. The patient suffered from extreme epilepsy, that resulted in the surgical removal of his medial temporal lobe and parts of the hippocampus and amygdala. Through the surgery his epilepsy improved, however, the consequences came in the form of anterograde amnesia, that comprised his abilities to create new memories.

Despite his difficulty in forming new declarative memories, his procedural and short-term memory that Alan Baddeley (1974) refers to as the working memory, remained intact. Brenda Milner (1957) also learned that his digit span was completely normal she observed this when she tested his ability to repeat the numbers that spoke, which he was able to do perfectly – however his retention of those numbers was only for a number of few seconds, due to damage to his brain. Milner also examined H.M’s motor skills by presenting him with a mirror-tracing task, where he would draw the outline of the images in front of him by merely looking at the mirror. His task performance gradually improved over time as he was able to unconsciously retrieve this skill memory, however, he was unable to actually remember learning or practicing it each time. This shows that perhaps there is some leak from the short term memory to the long-term memory, particularly when it comes to unconsciously learned skills. The observation of HM resulted in the belief that the removal of or damage to the hippocampus, can result in a deficit in the long-term memory, H.M was able to provide us with some of the earliest insights into anterograde amnesia and the case study shows that long-term memory is not necessarily indefinitely and only stored in the hippocampus since H.M was able to recall memories prior to his surgery.

A double disassociation was also established through the studies of amnesia, in this case, it is where the short-term memory and long-term memory are connected in a way where both can undergo damage but with the other still intact. Patients with amnesia typically experience damage to their long-term memory with either little or no impairment to their short-term memory. This is generally caused by damage to the medial temporal lobe and hippocampus, hence effecting episodic memory. It can also occur conversely however it is rarer; patients can undergo damage to the short-term memory with unimpaired long-term memory. This is usually caused by damage to the parietal and temporal lobes. In addition, semantic dementia patients lack semantic memory retrieval whereas their episodic memory is unaffected. In contrast, amnesic patients have a deficiency in episodic memory however their semantic memory remains rather intact.

To conclude, the various studies of amnesia have provided us with crucial information that is key to developing evidential theories about memory. Psychologists and Neurologists alike, have been able to systemically divide and organize the different sectors that the memory consists of, their differences and the distinct way in which they work together to retain information. It has also aided in the understanding of the functionality of the brain in relation to memory. Nonetheless, as our knowledge is predominately based on case studies and their findings, it is difficult to then generalize to the wider population, as these studies are largely based on unique individual cases.

Contrastingly, anterograde amnesia is described as the inability to acquire and retain new information, after the development of amnesia. This type of amnesia represents a breakdown of the established processes of retention starting from the second step, as the brain completely lacks the ability to transfer the information into the long-term memory. Patients are able to gather information, but this is retained for a significantly shorter period of time, even as short of a few mere seconds. Albeit, this is the worse of the two types as it has no cure, but simultaneously it is the more interesting aspect of amnesia as we are able to explore the other capabilities of the brain. The two main distinctions of long-term memory are a declarative/explicit memory and non-declarative/implicit memory. The former store's information that requires a conscious recollection. This memory can be further divided into two sub-divisions: episodic memory and semantic memory.

Episodic refers to memories of personal experiences including their time and the location of these events. Whilst the semantic memory retains knowledge we have obtained through education such as worldly facts and history. Studies and observations into the sub-divisions by Spiers et al (2001) found that the two were distinctively different. He examined 147 cases of patients with amnesia with damage to the hippocampus area and discovered that there were impairments to episodic memory in all cases, however no substantial damage to the semantic memory. However why this occurs is still being explored. On the other hand, non-declarative memory stores learned skills that can be retrieved unconsciously, allowing individuals to perform actions by rote. This can also be subdivided into two categories: procedural memory and priming.

Procedural memory pertains to skills such as riding a bicycle or tying your shoelaces, these motor actions do not require any conscious thought or effort in most cases. Finally, priming refers to how the prior exposure of a stimulus affects the processing of a later stimulus, both of which share a relation. For example, an individual who is presented with an auditory stimulus of a dog allows a later auditory stimulus of a dog to become easier to recognize, due to their connection. Thus, the first audio would be referred to as the prime, which aids the processing of the audio when presented the second time. Henry Gustav Molaison (1926-2008), familiarly known as H.M was a patient suffering from amnesia, from whom studies were developed that were particularly influential in the development of the understanding of memory. The patient suffered from extreme epilepsy, that resulted in the surgical removal of his medial temporal lobe and parts of the hippocampus and amygdala. Through the surgery his epilepsy improved, however, the consequences came in the form of anterograde amnesia, that comprised his abilities to create new memories. Despite his difficulty in forming new declarative memories, his procedural and short-term memory that Alan Baddeley (1974) refers to as the working memory, remained intact. Brenda Milner (1957) also learned that his digit span was completely normal she observed this when she tested his ability to repeat the numbers that spoke, which he was able to do perfectly – however his retention of those numbers was only for a number of few seconds, due to damage to his brain. Milner also examined H.M’s motor skills by presenting him with a mirror-tracing task, where he would draw the outline of the images in front of him by merely looking at the mirror. His task performance gradually improved over time as he was able to unconsciously retrieve this skill memory, however, he was unable to actually remember learning or practicing it each time. This shows that perhaps there is some leak from the short term memory to the long-term memory, particularly when it comes to unconsciously learned skills. The observation of HM resulted in the belief that the removal of or damage to the hippocampus, can result in a deficit in the long-term memory, H.M was able to provide us with some of the earliest insights into anterograde amnesia and the case study shows that long-term memory is not necessarily indefinitely and only stored in the hippocampus since H.M was able to recall memories prior to his surgery. A double disassociation was also established through the studies of amnesia, in this case, it is where the short-term memory and long-term memory are connected in a way where both can undergo damage but with the other still intact.

Patients with amnesia typically experience damage to their long-term memory with either little or no impairment to their short-term memory. This is generally caused by damage to the medial temporal lobe and hippocampus, hence effecting episodic memory. It can also occur conversely however it is rarer; patients can undergo damage to the short-term memory with unimpaired long-term memory. This is usually caused by damage to the parietal and temporal lobes.

In addition, semantic dementia patients lack semantic memory retrieval whereas their episodic memory is unaffected. In contrast, amnesic patients have a deficiency in episodic memory however their semantic memory remains rather intact. To conclude, the various studies of amnesia have provided us with crucial information that is key to developing evidential theories about memory. Psychologists and Neurologists alike, have been able to systemically divide and organize the different sectors that the memory consists of, their differences and the distinct way in which they work together to retain information. It has also aided in the understanding of the functionality of the brain in relation to memory. Nonetheless, as our knowledge is predominately based on case studies and their findings, it is difficult to then generalize to the wider population, as these studies are largely based on unique individual cases.