We are generally not aware of most of the previous experiences that we can some- times access. So in that sense, although remembering is part of conscious thinking, the memory (the ‘record’ or ‘store’) is not. Memory traces can be considered at the systems level as resources that can be accessed by the executive processor that gives rise to consciousness.
At the systems level then, the cognitive system includes a component, in effect the association cortex, that is able to in some sense represent previous experience in a form that allows later access to those ‘records’ of prior experiences. We represent current experience in memory so that we can in some sense access (remember) it later. As subjective experience is assumed to arise from processing at a certain level in the cog- nitive system, this implies that in some sense the output of processing is ‘stored’, and can later be accessed, leading to a subjective experience (e.g. something remembered) which is to at least some degree similar to the original experience (e.g. a perception).
Of course, we have no independent way to know if our experiences of remembering previous experiences are true to the original experience – and so we tend to assume that when we experience particularly vivid and apparently realistic ‘remembrances of things past’, then these experiences are true to the original experience being evoked. However, it is also a part of everyday experience that it is not unusual for two people who think they clearly remember the same past event to actually produce contrary reports which might lead us to suspect that we cannot always rely upon what appear to be clear memories of the past. A popular musical song, ‘I remember it well’ by Lerner and Loewe, draws upon such an experience for comic effect.
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As the physical basis of the processing that correlates with thinking at the mental level is considered to be electrical activity, then this would suggest that either the store must be some kind of maintenance of that particular pattern of electrical activity associated with that particular conscious experience or a representation of it in a different form. It appears that patterns of electrical activity are not themselves maintained in the brain permanently, but rather the activity level of different neural circuits shifts over time: a pattern of activity relating to an experience will die away, but may become active again at some later time.
Current thinking (at the physical, brain level) then is that the store does not consist of the original patterns of electrical activity, but rather modifi cation to circuits of neurons which when activated can reproduce something like the original pattern. In other words (at the functional, system level) memory storage involves another process of coding of information in a new form (e.g. from electrical signals to changes in synapse confi gurations), and memory retrieval involves reading the original information back, decoding it (activation of the network of neurons).
So it would seem that when we remember an object or event we previously experienced, we are decoding a representation of the processing we experienced as perception, that was itself (see Chap. 4 ) the output from a different part of the cognitive system as a result of preconscious processing of a signal from the sensory interface, where an original stimulus had been coded into an electrical pattern.
Long-Term Memory
The system component that is considered to be responsible for this ability to access and apparently relive previous experiences is usually known as long - term memory (LTM), as information stored in LTM is potentially accessible for decades. Other components of the cognitive system are considered to be able to store information in the shorter term, for example, to support the ‘high-level’ processing (when we are conscious of thinking about something or working on a problem).
LTM includes the means to make representations of different kinds: of different modes (visual, abstract, etc.) and degrees of integration and complexity. It has been noted that ‘long-term memory is replete with schemas, schemata, stories (experi- ences), procedures, behavioral sequences, patterns, and many other structures’
(Jonassen, 2009 , p. 18).
At one time LTM was considered to be complemented by another functional unit, widely known as short-term memory (STM), that was thought to be a discrete component of the system so that experiences were said to be stored in STM until they can be transferred into LTM. This idea is no longer widely accepted, and it has been argued, rather, that ‘the storage of short-term memories is inextricable from the reactivation of the long-term memories that, by context or similarity, any new experience evokes’ (Fuster, 1995 , p. 4).
There are components of the cognitive system that store information over short periods, but with different functions to that previously assigned to STM. So what is
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usually called working memory (WM), and seen as an aspect of executive function, is widely accepted as an important component of the cognitive system (see below).
WM relates to what is consciously being considered, rather than an intermediate memory store as STM had been understood. The buffers in which perceptual infor- mation is stored (see the previous chapter, including Fig. 4.8 ) can also be considered a form of short-term memory, although again this is not how STM was understood.
These buffers only operate over very short time periods to buffer information during active processing, not – as STM was understood – over durations of minutes and hours as a kind of queue of material ready to be stored in LTM.
LTM is considered to be in effect of limitless capacity. Clearly if LTM is made up at the physical level of neural ‘circuits’, then its capacity must actually be fi nite, but it is generally thought that the capacity of LTM is suffi cient to support its use throughout a human lifetime without becoming a limiting factor. Age may bring defi ciencies in memory function, but these arise from other characteristics of the system, not a limit in capacity.
It is widely suggested that once a representation is formed in LTM, through the formation of a memory trace, it is not actively erased, although the trace might get degraded. Certainly memories that are not activated for long periods may become very diffi cult to access, but the trace itself may be present, even if not readily located and activated. This is suggested by experiments during surgery on conscious patients, which have shown that electrical stimulation of parts of the cortex can trigger vivid recollections of experiences that the patient claims not to have thought about for many years. As the brain does not have pain receptors, brain surgery does not require general unaesthetic. Further, as each brain has a somewhat idiosyncratic mapping of functions onto the cortex, surgeons may actually use patient feedback as a guide during surgery. Memory circuits have a threshold of activation, and in normal con- ditions some may receive insuffi cient stimulation for activation – opening the skull and directly applying an electrical potential with an electrode presumably provides a suffi cient magnitude stimulus to activate an otherwise long-dormant circuit!
The key role of accessing representations during recall was, for example, noted by Wong in a study looking at how the use of self-generated analogies might support stu- dents’ (in this case, student teachers) developing scientifi c explanations. Wong noted that
When participants experienced diffi culty explaining the phenomena, the problem was often one of access rather than availability of knowledge. For example, although two participants had learned a great deal about air pressure during their undergraduate and graduate training in the physical sciences, neither was able to access or apply appropriate elements of this knowledge in their initial explanations. For both of them, analogies triggered relevant knowledge during the task. (Wong, 1993 , p. 1267)
The Cortical Basis of Memory
Perception and remembering are different functions carried out in the cognitive systems and so were shown in Fig. 5.1 as involving different modules. However, memory appears to be widely distributed in the cortex, and the basis of memory
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when we recall something may not be structurally distinct from the brain circuits that interpret experience to produce perceptions for us:
Memory is a functional property, among others, of each and all areas of the cerebral cortex, and thus of all cortical systems. This cardinal cognitive function is inherent in the fabric of the entire cortex and cannot be ascribed exclusively to any of its parts. Furthermore, as the cortex engages in representing and acting on the world, memory in one form or another is an integral part of all its operations. (Fuster, 1995 , p. 1)
Fuster argues that memory is ‘global’ and ‘nonlocalizable’ within the cerebral cortex, although individual memories can be ‘more or less widely distributed over the cortical surface’ (p. 1). According to Fuster, memory
is made of myriad idiosyncratic associations between that common fund of specifi c sensory and motor memory, which already lies in primary areas at birth, and the experience that has accrued thereafter in areas of so-called cortex of association, which means practically anywhere else in the neocortex. (Fuster, 1995 , p. 1)
Fuster offers the following basic notions about memory (p. 2):
• A memory is in effect a network of neocortical neurons and the connections linking them together.
• A memory is formed by the concurrent activation of ensembles of neutrons (which represent aspects of the internal and external environment and motor action).
• The networks are modifi able by further experience.
• Individual neuronal ensembles may be part of multiple networks and so a range of representations (in each of which the ensemble is part of a different network).
Furthermore, according to Fuster, ‘the cortical substrate of memory, with its many potentially infi nite representational networks, is very nearly identical to the connective cortical substrate for information processing, in perception as in action’
(p. 2, emphasis added ). This commonality between the substrate for ‘storing’
memories and for processing information (see Fig. 5.2 ) is potentially signifi cant for how we think about memory, that is, although it may be helpful to think of memory as functionally different to information processing, this could be misleading.
So in this respect our cognitive systems are quite different from an electronic computer where information that is stored and accessed in a discrete memory unit such as a hard drive or a USB pen drive is only changed when it is deliberately deleted or overwritten. The storage devices in our computer are just storage devices, and information has to be copied from them into the computer’s working memory for processing. In humans, however, a good deal of preconscious processing occurs in the ‘store’ itself, and potentially modifi es what is stored, so memories accessed by consciousness cannot be considered to have been securely stored since they were initially laid down.
From a biological and, in particular, evolutionary perspective, the notion that the same physical components may develop several functions will not seem surprising.
The evolutionary process seems to often involve existing structures being recruited
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for new roles. However, this interpretation of the physiology may be quite signifi cant for learning and remembering. Arguably:
• All of our perceptions are based upon the activation of combinations of existing neural networks, which in effect refl ect memories of previous experience.
• The activation of neural networks during perception modifi es neural connections and leaves those networks (which are in effect components of our memories) changed.
The former point is highly relevant to models of learning and in particular the basis of constructivist approaches to teaching and learning (see Chap. 15 ). If everything we perceive is based upon the activation of combinations of previous memories that have been ‘judged’ (in the cognitive system, through the activation of particular networks in the cortex) to give the best match to current sensory inputs, then there
Fig. 5.2 Considering memory and perception to be different functions of the same brain
structures
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is a strong biological basis for constructivist pedagogy. Constructivist ideas about teaching emphasise the importance of working from the learner’s current ways of understanding and thinking about topics (Taber, 2009b ).
Similarly, if our memories are being modifi ed all the time, then they cannot be considered to be accurate records of specifi c experiences, but rather should be seen more as some kind of democratic averaging of our interpretation of past experiences. This is an extreme suggestion of course, and it may seem to be over- stating the case. However, in principle, we cannot assume memories are accurate representations of distinct , specifi c experiences . This is something that will inform the discussion of students’ recollections later in this chapter.
It would also seem that if, as Fuster reports, information processing uses the same neural networks that act as the basis for memory, then studies into student thinking cannot in principle be separated from studies into memory. That is, the idea that there is a ‘content free’ processing apparatus into which the researcher can feed input to explore thinking is false. This point will be important when we consider the nature of research into student thinking (see Chap. 7 ).
Active Memory and Focus of Representation
The networks in the association areas that provide the basis for remembering may be active without us being aware of memories. The pattern of ‘active memory’ in various part of the cortex at any one time has been described as a form of parallel processing, and most of this activity occurs without conscious experience (Fuster, 1995 ). In a sense then, it seems memory may be active without our awareness.
This is something that would not surprise the adherent’s of Freud’s psychological theories. In contrast, a limited portion of this active memory that has been described as the ‘focus of representation’ and is considered to be activated by serial processing is linked to conscious experience (Fuster, 1995 , p. 5). This is represented in Fig. 5.3 .
Figure 5.3 offers two possibilities (metaphors) for how this might work. The left- hand fi gure is intended to imply that the ‘focus of representation’ involves transferring the representation from the active network and re-representing it in the executive module (e.g. within working memory, see below). However, another possibility is that the executive acts more like a metaphorical ‘spotlight’ highlight- ing the focus of representation, at which point it becomes conscious.
Memory Is Reconstructive
One of the least controversial – but most important – observations is that memory is not perfect. Instead, memory is prone to various kinds of errors, illusions and distortions.
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An important aspect of memory function, consistent with this way of thinking about memory within the cognitive system, is that remembering is a constructive process (Parkin, 1987 ). Certainly in the case of what is called episodic memory when we recall an ‘episode’ of previous experience, research suggests that what we recall may be considerably different from what is objectively recorded to have been the case – although we are not aware of these distortions – as what is presented to consciousness usually seems a complete account. In the everyday discourse of the lifeworld, there is a common distinction between remembering something or not remembering (forgetting), but it is usually taken for granted that what we clearly remember will be accurate. On occasions where what we remember clearly appears to be contradicted by strong external evidence, we are surprised and sometimes disturbed as what we feel we know based on our strong recollections is a key part of our foundations for understanding and acting in the world. Despite the common folk notion of memory as fallible but largely reliable, research suggests that ‘memory is not a literal reproduction of the past, but rather is a constructive process in which bits and pieces of information from various sources are pulled together’ (Schacter &
Addis, 2007 , p. 27).
Extreme cases that are found in clinical examination of patients with certain medical conditions are referred to as confabulation , that is, ‘fabricating an answer to cover up a memory defi cit’ (Parkin, 1987 , p. 114). Patients apparently give reports that they experience as genuinely remembered, although actually incorrect.
Kopelman ( 1987 ) reports one patient insistent that she needed to get home as it was part of her routine to cook for her mother – although the mother had actually been dead many years. As in this example, confabulation seems to be primarily a
Fig. 5.3 At any one time a range of networks representing memory traces will be active, but only one will be the ‘focus of representation’
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phenomenon of episodic memory, rather than semantic memory (Barba, 1993 ).
Clinical examples of confabulation tend to be considered as either ‘momentary’, that is, ‘sensible but untrue’ accounts based on genuine memories inappropriately accessed (reporting genuine but distant experiences as if recent or current) or ‘fantastic’, involving reports that ‘are often markedly bizarre and bear little, if any, relation to real events’ (Burgess, 1996 , p. 360).
Although confabulation is particularly associated with patents with memory defi cits, similar (non-fantastic) confabulation seems to be common in people with normal memory function. Kopelman reports a study comparing a group of patients diagnosed with particular medical conditions with a healthy comparison group.
As part of the procedure, the participants were read a short story and asked for immediate and delayed (45 minutes later) recall. The participants in the healthy group were also asked for a further report a week later.
The examples reported in Table 5.1 are from the ‘normal’ healthy participants, and those marked by an asterisk (*) were from the immediate recall condition.
Kopelman found that details confabulated in an early report tended to be repeated during later reports. It seems that the non-fantastic forms of confabulation known to be common in certain memory-impaired conditions may actually refl ect a char- acteristic of normal memory. To clarify, it seems that normal people when presented with an account , and asked for almost immediate recall , will not only ( as we might expect ) miss some details , but will actually ‘ remember ’ additional details that were never part of the account , and when they do those embellishments will then often be recalled on later occasions as being part of the original information . This account might well ring true to teachers, where common professional experience is that what pupils remember being taught often bears only limited similarity to what was actually presented by the teacher.
One interpretation of why memory is so fallible is that when the memory trace is activated, the pattern of neural activity usually under-specifi es the original experience that is being remembered. There is here, then, a kind of ‘fi lling-in’ (see Chap. 4 ) to construct a feasible account from the fragmentary information available. An alterna- tive, if potentially complementary, interpretation offered by Schacter and Addis ( 2007 ) sees the basis of this infi delity as adaptive. They suggest that the apparatus used for remembering is also that used for imagining future events and so has to be
Table 5.1 Examples of confabulation reported by Kopelman ( 1987 )
Source account Examples of ‘recalled’ detail reported
Anna Thompson of South Bristol, employed as a cleaner in an offi ce building, reported at the Town Hall police station that she had been held up on the High Street the night before and robbed of 15 pounds. She had four little children, the rent was due and they had not eaten for 2 days. The offi cers, touched by the woman’s story, made up a purse for her
She was a cleaner at a hospital who was stopped by police on the High Street*
Anna Thompson of Sussex*
Aged 44*
The police made up a sum of 50 pounds*
Thieves took her money near a railway station
She has a little boy, aged 2 The Nature of the Learner’s Memory Store