Cognitive Psychology
The Brain and its Role in Memory
Within the human brain it-self is the function of memory, which in essence is the way in which information is encoded, retained, and then recalled in order to process current information. It is this process that allows us to draw on past information and experiences in order to respond to situations on a current level, and it is from this as well in which our perceptions stem (Sternberg, 2006). Key to this process is a portion of the brain called the hippocampus, and which plays a pivotal role in the process of memory, and is the area of the brain within the cerebral cortex where the different sensations we experience are processed and then stored. This is particularly important in terms of episodic memories, which is where our personal experiences and the important events of our lives as stored for retrieval, and which are "established" within the hippocampus (Buzsaki, 2005). The hippocampus encodes the "declarative information" it receives by "integrating and consolidating" the information and then works in the transfer process of that information into the long-term memory, also known as the information we know or learn (Sternberg, 2006).
The memory process first begins with sensory information first being encoded within the brain, and then organized within the memory system in a manner in which representation is assigned to that information. Once the information is encoded, it can then be organized and stored within the various levels of the memory system for later retrieval. These are three distinct stages that occur, and depending on what school of thought subscribed to, the information is transferred through the neurons in the brain and the memory stores that information into our memory system to be used by our working memory. It is these networks of neurons within the hippocampus that is thought to link the spatial navigation system to episodic memory, which originated within the hippocampus itself (Buzsaki, 2005).
The hippocampus is "considered a single giant cortical module with rich recursive excitatory connections" (Buzsaki, 2005, p.1). These connections, also known as neurons, within the hippocampus work in different combinations or networks, and it is this "ensemble" of place cells within the hippocampus that form a map within our memory, which we later follow when retrieving stores information (Buzsaki, 2005). These maps are carefully encoded so that no interference within the memory process are experienced in order to ensure that memories are stored and re-mapped separately, and not mixed up when retrieved. In addition, Buzsaki (2005) cites that the neuron networks within the hippocampus encode the information received into "firing patterns", and these patterns are what form the maps that are used to retrieve the episodic memories.
Most important, these patterns are then revisited during sleep, information is purged and stored, and research now shows that it is during this process that learning actually occurs (Miller, 2005). Current research has shown that REM sleep actually plays a big part in the processing of our memories and the learning process, and actually aids in the "consolidation of procedural learning and memory tasks" (Stickgold et. al, 2001). More specifically, it is now thought that our dreams are actually the representation of this process, and go much father than Freud could have ever imagined. This implies that there is actually a "physiology of sleep" and, research on memory, sleeps and rats suggests the following:
"Theta rhythms in REM may support information transfer from neocortex to hippocampus, where theta waves enhance LTP, considered critical for hippocampal memory formation. Neural network simulations have suggested that such an alternating "hippocampo-neocortical dialog" could enhance the encoding of hippocampally dependent memories in the neocortex. Phasic ponto-geniculo-occipital (PGO) waves, which activate visual and motor cortices as well as the amygdala and hippocampus, are seen during the transition from NREM to REM and throughout REM. These waves may play an important role in memory consolidation in the rat and have been proposed to reactivate memory traces during REM dreaming"(Stickgold et. al., 2001).
Current research also suggests that there are varied forms of neuron patterns that can occur within the hippocampus, and which imply that the codes used to separate neuronal patterns for episodic and spatial memory can differ. This is thought to be the result of different "firing rates" within the networks of neurons within the hippocampus, however the locations of the firings within the neuron networks did not change. This is important because "these independent encoding schemes may enable simultaneous representation of spatial and episodic memory information", which means the hippocampus does have the ability to create spatial and non-spatial episodic memories (Leutgeb et. al, 2005) depending on the place condition within the chambers of the hippocampus.
The hippocampus actually works in different stages, and these stages are connected and work "recurrent" of one another to create representations needed for memory. Again, it is these neuronal networks that differentiate these stages, also known as stages CA3 and CA1. Leutgeb (2004) cites that these stages are a "recurrent network of densely interconnected pyramidal cells (CA3) and a feed-forward network with almost no intrinsic excitatory connections (CA1)", and each stage plays an important, but separate part in how memories are created. Each stage has separate and specific firing place conditions, which create different "input patterns", and which insure that interference does not occur, which would result in stored information becoming confused, corrupted or forgotten.
As with any part of the brain, when damage occurs to the hippocampus, memory loss can occur. These cognitive losses are usually the result of lesions on the brain, and the losses that occur are not a function of forgetting, but a function of an inability for stored information to be recalled and sometimes even acquired (Gaffan, 2005). When this happens, a person will experience an inability to retrieve information stored in the brain that they otherwise would be able to do, and also may even be unable to fire the neurons within the hippocampus required for learning and retaining knowledge. Research suggests that the reason this happens is that a person is unable to retrieve the representation needed to in turn retrieve the memory from within the memory stores of the hippocampus, resulting in memory loss. It is much like losing an important path in a computer necessary to find a file on a hard drive, and without that path, the information is lost within the information stores on the hard drive. Loss of memories can be devastating to an individual as our memories are what make us different from one another, and give "continuity" to our experiences and our lives overall they are what make us who we are as they are the foundation of our perceptions and our behaviors (Miller, 2005).
Main Theories of Forgetting
The two main theories of forgetting are Interference Theory and Decay Theory. Both of these theories work to try and understand why we forget some information easily while other information we never forget. Sternberg (2006) states that interference "occurs when competing information causes us to forget something" while decay "occurs when simply the passage of time causes us to forget" (p. 207). Both of these processes take place within working memory where the information is stored, and are believed to be a resolved within the frontal lobes of the brain by a series of "multiple cognitive control mechanisms" that actually work to overcome the interference response (Badre & Wagner, 2005, p.1).
Interference Theory looks at the way that we recall information stored in our short-term memory, and how competing information causes a problem in recall, sort of like a hiccup in the memory process. In this theory it is proposed that it is the delay intervals between the information is what causes the interference, or forgetting occurs, particularly when rehearsal or repetition was not possible. It is thought that the rehearsal of incoming information is what cements it in our working memory for easy recall later, and is one of the aspects of interference theory that make it more easily tested and thought to be more reliable than other theories of forgetting (Sternberg, 2006).
Interference Theory there is thought to be two distinct types of interference, which are retroactive interference and proactive interference. Retroactive interference is the result of some type of activity that occurs after the learning process has been completed, but we have not had the recall it as of yet. In other words, as a result of the interference we experience, we are unable to recall information that we have already learned and that is stored in our working memory. Again, the link appears to be with the need for repetition and using that information again before it is forgotten. The theory suggests that it is repetition that eliminates the interference and causes easy recall of stored information which stays stored within the memory, but is not recalled.
Proactive interference is the result of interference actually occurring during the learning process, causing a block between the information being learned and stored in the short-term memory. In other words, it is the result of "a memory of a past experience can interfere with processing during a subsequent experience" (Badre & Wagner, 2005, p.1). Most important to note is that people utilize the different schemas, or structures, within their minds to organize the information they receive, and those individual schemas do seem to play a part in their memory processes and the amount of interference or "distortion" they experience (Sternberg, 2006). Proactive interference also seems to be affected by the amount of time that occurs between the presentation of information and the retrieval process.
Both retroactive and proactive interference are now thought to be a "complementary phenomenon" rather than two separate experiences as once thought, and each type may be more dominant depending on the situation and the delay times associated with the experience (Sternberg, 2006). Task interference is also rooted in Interference Theory and "task interference primarily reflects an attention allocation policy stored in memory when intentions are encoded" (Loft et. al., 2008. p.1). In other words, new research suggests that it is actually our underlying intentions that actually affect the amount of interference we experience and our ability to recall or re-perform a task. One example might be getting the phone number of a person you want to talk to again as compared to one that you do not intend to ever speak to again. Chances are high that you will recall the number of the person you intend to speak with again while forgetting the number if the person you did not intend to speak to again. This research does create a weak point in the theory as is suggests that we actually have control over the amount and type of interference we experience within our working memory.
Decay Theory is another view of forgetting that "asserts that information is forgotten because of the gradual disappearance, rather than the displacement, of the memory trace" (Sternberg, 2006, p. 211). Unlike interference theory, this theory suggests that a memory must be used or it will literally disappear from the working memory rather than be stored there, but not easy to recall. The "use it or lose it" concept applies here, and unlike Interference Theory, the memory will be gone for good should it not be used.
This is actually a very controversial part of past memory recall, and particularly regression therapy, where accuracy and validity are often in question. Colbert et. al (2007) cited that "although previous studies have consistently reported different forgetting rates for true and false memory when tested with recall, studies comparing the rates of decay for true and false recognition have reported inconsistent results" (p.1). This shows a substantial weakness in the theory because of its difficulty to test and because of the inconsistent results reported when decay rates were tested. Most important, the result of Colbert's research suggest that false memories actually decay at a faster rate than true memories, and false memories are the result of a person wanting to believe that it actually did happen causing them to have to "distort" the memory or recreate it within their memory.
Sternberg (2006) and current research does suggest that interference theory holds more water than decay theory because if its ease in testing. However, interference theory does have its problems, particularly in terms of how it affects the long-term memory, which can also lead to "memory distortions" as in decay theory. In addition, new research also suggests that there are actually more than one "rehearsal mechanism" that can explain why some memories are easily recalled in some while others are not so easy to recall. The difference seems to lie in verbal working memory, and in particular the information waiting to be processed in the working memory that has a limited capacity and limits the amount of information that can be processed and recalled, explaining why we experience interference during this process (Hudjetz et. al., 2007).
Levels of Processing Memory
The levels of processing model of memory is a model that suggests memory is not broken down into three levels, or any "specific" levels for that matter, but that memory actually is continuous and the depth of its ability depends on the depth of one's ability to encode information. This model theorizes that the possibilities are endless in relation to memory and one's ability to have varying levels of memory. Sternberg (2006) states that "there are no distinct boundaries between one level and the next, and the emphasis in this model is on processing as the key to storage". (p. 167). In other words, a person's ability to store and process memory is dependent on their ability to encode it, and how easily a piece of information is recalled is dependent on how deeply it was processed within the memory system.
The levels of processing in this model appear to be tied to three orders of depth, which are "physical, acoustical and semantic" (Sternberg, 2006). Sternberg (2006) cites that current research suggests that the deeper the processing required for these levels, the easier and faster it was for people to recall that information, and particularly if the information was connected or linked to other information. This model does fall in line with other theories of memory that suggest we organize and categorize information within cognitive structures within the brain. Some examples would be theories of schematic representations and procedural models, which all use the concepts of cognitive structures and processes of categorization within the theories.
Also important to note in this theory is that recall seems to be connected to the meaning assigned to the information being processed, also known as the self-reference effect (the semantic level of processing) (Sternberg, 2006). If the information presented invokes a personal experience or is something that the person can relate to on a deep level, it is stored much deeper within the memory and is therefore recalled much easier. These memories are connected to the schematic representations within our cognitive structures, and the level ability to recall is directly tied to the sequence and levels of encoding that are important to us, which causes our working memory to search for matches or patterns within the memory structures (the acoustical level of processing).
The physical level of processing in this theory is connected to the visual aspect of the memory process. Current research suggests that it is the symbols within memory that create the connection for recall. This is particularly true in cognitive reading system where meaning is actually assigned to symbols (letters, punctuation etc.). It is the meaning and representations assigned to those symbols that determine how that information will be encoded, stored and organized for later recall (Reimer, Lorsbach & Bleaknet, 2008). It is also the representations assigned to the symbols that make it possible for the brain to cognitively process and recall the words and meanings assigned to the symbol, or words. Research by Inhoff et. Al. (2008) also shows that the visual processing that assigns meaning to those symbols that also have a role in how deeply that information is recalled.
Memory and Eyewitness Testimony
When considering whether eyewitness testimony should be used as the sole or primary form of evidence in a court case, the research clearly shows that this should be avoided as "mistaken eyewitness identification is understood to be a leading cause or at least precursor of erroneous conviction" (Devenport & Cutler, 2004, p.1). The first and most important thing to note is that there are "limitations" on eyewitness testimony as it is based on memory and recall, as well as emotional responses and perception, which can differ from person to person (Ogloff & Cronshaw, 2001). As stated by Ogloff and Cronshaw (2001), it is the responsibility of the judge and jury to examine and analyze eyewitness testimony, and although there is "common sense" involved, a judge and jury must be aware of how to accomplish this in order to analyze and judge the eyewitness accounts accurately. In order to do that, a judge would need to be clear on what limitations there are on memory, the science behind cognitive processes. In addition, it must be clear as to what things can affect recall and how memory is received, processed, encoded and stored into memory and that this process, although physically the same for everyone, is not the same in terms of mental ability. This means that eyewitness testimony cannot be the only form of evidence as its accuracy can be in question.
One of the main problems is that a judge or jury are not a mental health professionals and therefore not qualified to judge whether a person may be suffering from a mental health issue and how that can affect their recall, which is why having a psychiatrist or psychologist as an expert witness there to assist is recommended (Ogloff & Cronshaw, 2001). However, this also is not guarantee that the testimony will be accurate or factual as the mental health professional is also acting on their mental and cognitive abilities, and testifying based on their perspectives, which are also not necessarily factual and can be based on their opinions and cognitive schemas. Also important is that even though ethics is at the foundation of the scientific fields, some expert witnesses (mental health professionals as well) can be "bought" or have an agenda themselves (Ogloff & Cronshaw, 2001).
On addition, eyewitness testimony is opinion based and therefore not always grounded in fact, and this must be carefully considered when examining these testimonies. Objectivity and sticking to the facts is the only way a judge or jury can consider all of the eyewitness testimony and try and make a determination. As stated before, the cognitive limitations or the existence of possible mental disorders can cloud the facts and make is possible that a person is unable to accurately process and then recall information. One example would be the limitations experienced by a person who has suffered trauma in a case and may be suffering from PTSD. One empirical study found that there are severe reliability measure deficiencies in a person's recall who may be suffering from PTSD, and this is especially higher during the first year after a person has experienced a severe trauma, which is the case with many victims during a trial (Koch et. al., 2005). The extreme emotional ups and downs associated with PTSD can interfere with the person's regularly ability to function, and recall is also a part of that functioning, and "what is important for legal purposes is that these adverse emotional states cause sufficient harm that compensation is appropriate" (Koch et. al., 2005, p.2).
Also important is the problem with "memory suggestibility", which is a particularly important problem when considering the testimony of children and those with past or repressed memory recall. Current empirical research has shown that the differences in cognitive ability and the "level of suggestibility" does seem to differ greatly, with "individual differences in accuracy were related to participant's gender, education and ethnicity" (Quas et. al., 2005, p. 1). These studies also show that there are many different variables that determine the reliability of not only the reliability of recall, but also in a child's ability to accurately and completely express what they recall. The current research on child testimony reliability has now even become more in question as scientific methods prove the unreliability and high levels of suggestibility possible.
For this reason many experts are stressing the importance of judges and jurors being trained in the scientific methods necessary to determine reliability in eyewitness testimony, specifically the encoding, storage and retrieval processes associated with the memory process (Quas et. al., 2005). The importance of this lies in the current research that shows juror judgment is affected by eyewitness testimony, and most importantly, can easily be swayed and influenced by opposing arguments and council (Devenport & Cutler, 2004). This is why expert testimony can help ensure that jurors and the judge get the facts as much as possible and are not easily swayed or affected emotionally in their decision process as a result of their own emotions, perspectives and / or experiences.
The next question that must then be considered is whether or not eyewitness testimony should be considered a viable tool in the court system and the answer really lies in the research on human memory. The answer is yes because "over the last two decades, valuable advances in the scientific understanding of eyewitness perception and memory have been made which can assist the court in their evaluations of eyewitnesses' reports" (Yarmey, 2001, p.1). What is important and does affect the reliability of the eyewitness testimony also falls on the courts in terms of how the eyewitness is instructed and how the questions are worded when presented. Current memory research and studies on memory patterns shows that these factors can affect understanding and memory recall, and when presented correctly have proven to be very reliable (Yarmey, 2001, Peters, 2001). When questions are presented correctly, eyewitness memory is probed and prompted for "optimal memory search" and "domain-specific information" (Brailey et. al., 2001).
As stated above, the neurological makeup of the human memory system varies from person to person in terms of ability, and this also seems to be true in terms of domain knowledge (Brailey, 2001). The key seems to be in the complex networks connections within a person's memory system, and their depth of ability to exhibit memory flexibility and selective memory search processes. Brailey et. al. (2001, p.2) cite that this process can be defined in Long -Term Working Memory Theory, which: "Posists that knowledge structures are formed in long-term memory that include both information relevant to a problem and a retrieval structure that can be cued easily from short-term memory. Thus, information about the conditions of retrieval can be combined with relevant knowledge with long-term memory to form intermediate knowledge structures that can be retrieved rapidly and altered as conditions within short-term memory dictate".
The implications of this research means that the conditions in which the information is received, encoded and stored can affect recall as well as the ability of a person's short term memory processes. Again, these vary from person to person and are dependent on numerous variables, such as race, gender, education, ethnicity all affecting domain structures within the brain. All of these affect perception, which not only affect the recall of an expert witness, but also the ability to remain unbiased and factual on the part of a judge or jury. Scientific and expert testimony should be considered as an important factor in analyzing eyewitness testimony, especially in cases of repressed memories and children, where "reliability and validity can be in question and must be carefully weighed against the facts as the concept of repressed memories becomes even more controversial when it forms the basis of either criminal or civil action against an alleged perpetrator" (Sugarman & Boney- McCoy, 1997, p.1).
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