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Journal of Physiology - Paris 101 (2007) 223–229

Development of extended memory

Katherine Nelson *

Graduate Center of the City University of New York, 50 Riverside Drive #4B, 365 Fifth Avenue, New York, NY 10016, USA

Abstract

Memory development is described in terms of a bio-social–cultural theory of human cognition. The development from a privateunshareable system of basic memory in infancy and very early childhood is framed within an experiential perspective wherein all memoryis derived from experience. It is the nature of changing experience, the result of both biological and social–cultural conditions that even-tuates in a changed memory system that enables long-term retention of episodic memories, thus establishing the autobiographical mem-ory system. The sequence of developments that interact to bring this about, many dependent on the acquisition of language, arediscussed.� 2008 Elsevier Ltd. All rights reserved.

Keywords: Memory; Experience; Development; Representation; Language and memory

1. Introduction

The ‘‘extended mind” in contemporary writing refers tothe extension of mind beyond the brain, specifically interms of embodied acquisition and use of information. Inthis account the extension of memory refers to embodimentand also to social and cultural sources. In a different way itrefers both to extending the retention of memory to longerperiods of time and to the extension of the contents ofmemory to sources beyond self experience, a topic that isof central theoretical interest here.

Memory is central to any theory of cognition. At everypoint in its development, memory reflects the interests andneeds of the organism; in humans these are often stronglyinfluenced by, even determined by, social conditions anddirections. Human memory is inexhaustible – it grows inresponse to needs and develops through self-organization.In recent decades the study of memory development ininfancy and early childhood has progressed steadily inmany directions, from its biological basis in the brain tothe socio-cultural basis of autobiographical memory

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* Tel.: +1 212 724 1538.E-mail address: knelson@gc.cuny.edu

(Nelson and Fivush, 2004). Much of this understandinghas been achieved from the bio-social perspective in cogni-tive developmental psychology that emphasizes thedynamic of change as new forms and functions emergefrom prior structures and their functions. These changesnecessarily involve the interactions of the organism withthe social and cultural environment as well as physicalaspects of the environment.

Dynamic systems theories have made important contri-butions to these developmental issues. Thelen and Smith(1994) and Smith and Thelen (2003) have made a convinc-ing case for the necessity of systems analyses to encompassthe complexity of developmental processes, although up tonow they have not considered social and cultural condi-tions as part of the cognitive system. A multi-causal sys-tems approach is central to Developmental SystemsTheory (DST; Oyama et al., 2001) which derives from abiological (rather than physics) base, appropriate to therange of complex contributions to human cognitive devel-opment, from neural systems to cultural systems of knowl-edge storage. Two broad questions are in focus inconsidering memory development in the early childhoodyears from this perspective. The first question asks what

aspect of memory develops in the first years of life. Ismemory in infancy like memory in later childhood and

Interactive Encounters

ecological

past experience

socially embedded

enculturedevolvedspecies

embodied

Fig. 1. Conditions on the experience and meaning derived from encoun-ters in the world that interact to produce memory. Based on Fig. 1.1 (page19) of Nelson (2007).

224 K. Nelson / Journal of Physiology - Paris 101 (2007) 223–229

adulthood? If not, in what way is it different? The secondquestion asks how memory develops from an earlier stateto later states. Is such development confined to the brainor are other capabilities or domains of competenceinvolved? If so, what are they and how are they involved?

2. Experience and memory

All memory begins in experience, and it is thereforeimportant to consider the nature of experience and howit changes with development in order to ground the discus-sion of memory development itself. Experience results fromencounters of individuals in interaction with the outsideworld, thus it is constrained by both internal characteristicson the one hand and external (i.e., environmental) charac-teristics on the other. Fig. 1 labels six facets of encountersof the organism in the world that influence the content andmeaning1 of an experience (Nelson, 2007). The bottom andleft side of the hexagon label bio-experiential characteris-tics, while conditions external in nature are found on thetop and right hand side. All are continually interactingand mutually influencing. The following brief descriptionsflesh out this representation.2

2.1. Evolved characteristics of the species constrain whatwe as members of the humankind can see, hear, or perceivein other ways, or act on, or bring to mind. This includeslifespan developmental limitations, such as the incapacitiesof infancy and regressions later in life. For example, infantbrains continue to grow rapidly for two years after birth,producing new neurons and pruning synapses, dependenton sensory-motor experience for registering and analyzingboth expected (by the evolved system) and unexpectedsights and sounds to complete perceptual connections, ana-lyze patterns and form categories. This high degree of post-natal neuronal growth and plasticity is unique to humans.Neuronal plasticity and the resulting functional flexibilitycontinues throughout childhood; major changes in thebrain take place in response to injury, in addition to thegrowth of old (e.g., executive function) and new parts(e.g., those for reading and writing, arithmetic and mathe-matics). These conditions are essentially the same for allunimpaired members of the species, but they affect experi-ence in different ways at different ages.

2.2. Embodiment is a variable quality that determineshow experience differs depending on the way the body isinvolved in the activity, as well as the size and conditionof the body. It includes the developmental state of thebrain, motor ability, and other basic systems. It also

1 I use ‘‘meaning” in contexts where often ‘‘information” would appear.This practice accords with the claim of the subjectivity of memory and itscontents. ‘Information’ is a neutral term that allegedly refers to objectivematters. Information is held to exist in the world and to be processed inthe mind. However, the claim here is that what gets into the mind and intomemory is subjective and is meaningful to the individual (consciously ornot). Thus meaning is the appropriate term for what is processed byindividuals.

2 See Nelson (2007) for details.

applies to aspects of abilities such as speech and literacy.The body changes rapidly and dramatically in the earlyyears, and at other points in development (e.g., puberty),and bodily characteristics vary widely among people bothin childhood and in maturity. For example, women gener-ally are smaller than men and thus experience many every-day encounters in a different way than most men do. Therapid growth of infancy and early childhood implies con-stantly changing experience. That memory is short-termin infancy and early childhood appears to be adaptive forthat period, when new sights and relations easily overrideprior memories.

2.3. Ecological conditions also change with different sit-uations and vary across geography and cultures. Theseconditions imply an adaptive advantage of general ratherthan specific cognitive capabilities in the human species.Too much specificity of innate knowledge would be a dis-advantage to a species that must adapt to a broad rangeof physical and cultural conditions.

2.4. Social embeddedness is a condition of all humanencounters, even those that we design for ourselves whenalone: we cannot escape the social world. Infants andyoung children are in the most thoroughly social worldof all: all of their most intimate functions – eating, sleeping,voiding and defecating – are overseen by supervisory oth-ers. The unusual biological immaturity of the human infantat birth and for many months and years thereafter requiresan extraordinary dependence on social caretaking and pro-tection to sustain the infant’s life. Thus the biological con-dition of human infancy is inevitably also socio-culturalwith implications for further development (Nelson, 2007).

2.5. The cultural conditions of experience overlap theecological (e.g., the artifacts, buildings, etc.) and the social(e.g., who interacts with the self, their hierarchical andfamilial place, and so on), and include also the languageand other symbols used in a situation, and the institutions(economic, educational, governmental, spiritual) that maydetermine the very nature of the encounter (is it play?

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school? work?). For the infant and young child prior toachieving good language competence much of the culturalsurround that might have special significance for adultslacks symbolic meaning for the child. This is true for muchof the language that is used daily, including for example,reference to past or future time. Cultural artifacts, institu-tions, and symbolisms that surround the child are inter-preted initially in terms of their subjective and pragmaticmeanings from the child’s perspective.

2.6. The last component – the history of prior experi-

ence, or memory – influences what meaning is taken froman encounter and how it may relate to or change what isalready in memory. Memory is essential to the derivationof meaning from any new experience, affecting the pro-cesses of differentiating, analyzing, categorizing, and repre-senting the experience in whole or in part. Far from beingan inert, objective, and neutral repository of information,memory is personal, subjective, meaningful, and dynamic.Experience and meaning are inherently subjective; theinterplay of the internal and external components ofencounters, that all vary with age, time, social conditions,and prior experience, produces for each individual a uniquemeaning and memory.

2.7. Perhaps the most important of the unique advanta-ges of the human mind is its capacity for sharing contentswith others.3 Whereas a child’s memory begins as totallyprivate in character – that is, it is unshareable – eventuallyit becomes largely social and cultural and only partly expe-riential and private. The principle vehicle for mind-sharingin human affairs is of course language, oral or written. Howlanguage enters and may change memory, and how itenables memory to be represented to self and others arecritical developmental questions. These questions havebegun to be investigated, as shown in what follows, butmuch more remains to be known from the bio-culturalperspective.

3. What develops in memory in infancy and early childhood?

3.1. We know a good deal about the parameters of mem-ory in infancy – how much and for how long a visual orauditory presentation or association may be retained, fromhours to weeks over the first 7 months (Rovee-Collier andHayne, 2000). Most memory researchers now generallyattribute infants and very young children with proceduralmemory (memory for routines and action sequences), andimplicit memory or perceptual representational systems(PRS). Implicit memory is unconscious; it becomes accessi-ble in context but cannot be voluntarily recalled out of con-text. It enables recognition of things previously experienced.These memory systems may be thought of as basic memory,systems likely shared with all mammals, although of coursevarying in their perceptual and motor inputs.

3 Yet memory as a function, process, or structure is almost alwaysstudied as an individual characteristic situated in the brain or mind.

3.2. The beginnings of a more clearly declarative or rep-resentational and recallable memory system have beentraced in recent years through the use of a delayed imita-tion paradigm (see Bauer, 2006 for review). Declarativememory is identified as conscious, voluntary recall notdependent on cues from the context of its acquisition.Adults as well as young children often display recognitionmemory that is inaccessible to voluntary recall and thusdoes not qualify as declarative memory. In the delayed imi-tation paradigm the infant watches a series of actions car-ried out with a set of objects and then after a delay intervalof days, weeks, or months, she is shown the objects againand encouraged to manipulate them. Replicating thesequence of actions observed earlier demonstrates recalland thus declarative memory (Bauer et al., 1994; McDon-ough and Mandler, 1994). This paradigm has successfullytraced the expansion of infant and toddler memory fromslight evidence of recallable memory at 6 months to moresecure memory lasting as long as one month at 9 months,and increasing intervals to at least one year by 2 years ofage (Bauer, 2006). It should be noted that memory for anepisode or an event sequence by infant or toddler rarelyincludes all of the available information critical to taskcompletion. Children remember aspects of the experiencesalient to themselves, and after one to three exposures tod-dlers may later remember part but not all of a three-partsequence of goal-oriented actions.

3.3. Declarative memory includes two sub-systems:semantic and episodic memory. Semantic memory orga-nizes cumulated facts, categories, and so on; episodic mem-ory retains single coherent episodes. Tulving (2005) arguesthat episodic memory is specific to humans, and is the onlymemory system that is both self-specific (autonoetic or self-

knowing) and about the past. Other memory systems aresaid to be atemporal, not about the past, in the sense thatthey preserve information from a nonspecific past of priorexperiences for use in a nonspecific future in relation topresent or future goals, actions, or plans. In other words,the function of a basic memory system is to serve the pres-ent and future; it is not designed for the retention of pastexperience for its own sake. This characterization appliesto PRS and procedural memory, types of implicit basicmemory in infancy. Semantic memory, which is usuallythought of as conceptual or factual memory, that is, gen-eral knowledge, is also not about the past, althoughacquired in the past. Tulving emphasizes that episodicmemory is private and subjective, representing an experi-ence as a memory of the past self, whereas semantic mem-ory may be personal and also have its source in and bewidely shared across social and cultural communities.

Although the delayed imitation studies provide evidenceof declarative memory, whether toddlers have episodicmemory is a controversial issue. Similarly, comparativepsychologists are actively seeking evidence for episodicmemory in other primates and other mammals and birds(Terrace and Metcalfe, 2005). They are attempting todisprove claims of the unique human characteristics that

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Tulving has made, especially given that it is difficult to dis-prove their existence in those without language. This is alsoa problem for those who claim that episodic memoryemerges in children at 4 or 5 years and that delayed imita-tion is not evidence for it (Perner, 2000).

3.4. The question of whether young children have epi-sodic memories is related to a striking phenomenon ofadult memory – the phenomenon known as childhood

amnesia – that many memories of childhood appear to lastvirtually for a lifetime with the exception of memories forevents prior to about 3½ years of age.4 On average thenumber of memories that adults can retrieve from child-hood under standard experimental conditions follows atypical ‘‘forgetting curve” back to the age of 5 or 6 whenthe number falls precipitously and approaches zero atabout the age of 3 years. Thus the time since the event doesnot explain its nonretention in memory.5 The memoriesinvolved are episodic – accounts of one’s life experiencesfrom the perspective of the self, located in a particular timeand space. Together with other memories and semanticfacts these make up the person’s autobiographical memory,

which typically begins to form around 5 years of age.In recent years much research has been carried out in the

effort to explain the origin of autobiographical memory(Nelson and Fivush, 2004). Childhood amnesia seems toimply that before the age of 3½ years children do not havethe kind of episodic memory that is retained in autobio-graphical memory. Recent research has focused specificallyon what children are able to remember from past experi-ences, in real life or in the laboratory, spontaneously orwith the support of parental questions and elaborations.This work has shown that children’s memories developfrom simple statements of facts and bits recalled to increas-ing complexity of narratives about personal experiences.How this advance is supported by language practices is dis-cussed in the next section in the context of an overallaccount of memory development in the preschool years.

3.5. It is clear that memory for an event is retained forincreasingly longer periods of time over the course ofinfancy and early childhood, and that declarative memorysoon supplements the implicit memory of early infancy.However, these changes over the early years cannot inthemselves explain developments in memory that eventuatein autobiographical memory at the end of the preschoolperiod. An additional factor traditionally held to be centralto memory development is how many items can be storedin short-term or working memory. With random lists ofwords or digits memory expands from 2 items at 2 yearsto 4 items at 5 years, implying that with age more can beremembered. However, Miller’s famous discovery of the7 ± 2 item limit on perception and memory (Miller, 1956)

4 This is not an absolute time barrier. For some people memories areavailable from the age of two, for others not before 8 or 9 years of age.

5 This is most easily understood by comparing the inability of 20-year-old students to recall events from 17 years in the past with the ease ofrecall by people in their 30s and 40s to recall events from their 20s.

was followed later by demonstrations that the problemsof both quantity and complexity can be reduced by symboluse. Thus, greater quantities of meaningful material,whether words or stories, can be remembered than appearsto be the case using random digits. For example, whenwords are presented in meaningful sentences more wordscan be remembered than when the words are presented aslists. Children certainly are more restricted in memory spanthan adults, but how this affects acquisition of meaningfulmaterial and its retention is unclear.

4. From basic memory to memory complexity

In this section I outline a proposed sequence of develop-ments of memory over the infant and early childhood yearsresulting in an adult-type autobiographical/episodic systemthat emerges from basic memory, is dependent to a largeextent on the incorporation of language into the system,and requires the differentiation of different sources andfunctions of memory in mind. The sketch of a developmen-tal scheme shown in Table 1 indicates the components ofthe system that become activated over time.

4.1. Basic memory

Basic memory can be assumed to constitute a beginningstate for infants, as well as for nonhuman mammals in gen-eral. As stated previously, basic memory consists of percep-tual patterns and action procedures. This kind of memoryserves sensory-motor functions and remains unconscious(thus implicit rather than explicit or declarative memory).As I first formulated this idea (Nelson, 1993) basic memorywas held to consist of events cumulated over time to form aknowledge base that could support decisions about actionsin the present and future. This proposal was based on workthat my colleagues and I had done with young children’sunderstanding and memory of familiar everyday events(Nelson, 1986). In such a system, recurrent situations andevents would be most relevant as the foundation for plan-ning action, while single episodes would be of less utilityunless they were in some way life-threatening. This divisionimplied a long-term general event knowledge system plus amemory for single non-repeated episodes that was rela-tively short-term.6 If the same kind of episode was notexperienced again, it would be overwritten after a shorttime, or its components might be redistributed as possibleentries in some other event.

4.1.1. Over-writing of prior knowledge appears to beadaptive to the changing conditions of early life. Theknowledge that infants derive from their experiences aredoubtlessly useful to successful adaptation to infant life,but much of this knowledge (e.g., actions involved in dia-

6 This division bears a family resemblance to the division betweensemantic and episodic memory in the declarative memory system, asdescribed earlier. As such, it might be that the continued retention of anepisode would account for some of the developmental changes observed.

Table 1Summary of developments in extended memory from infancy through early childhood

Beginning: Basic memory – implicit memory for events

Basic memory + recall (mimesis)Basic memory + biological (neurological)/experience ? mimesis 6–12 months

Mimesis (imitation, representation) + bio. dev. ? longer retention & consolidation 2 years+ social experience w/language ? word learning 2 years

+Basic language ? effects on retention: what, how long 2–3 years+Conversation (past, present, self, other, mental states) ? complex comprehension 3–4 years?Stories, narratives?Autonoesis, long-term episodic memory: self in time

Memory differentiation ? more than one memory stream, competing memoriesRestricted re-writing of past with presentOther source different from own experience ? autonoesis 4–5 years?Autobiographical memory 5–6 years

Note: ? indicates ‘‘enables” or ‘‘leads to”.

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per-changing or nursing) will have little applicability tolater interactions with people and things in the world.Over-writing of prior knowledge is quite generally observedin children’s task performance. For example, in a standard‘‘representational change” task (used in the study of theoryof mind) children are first asked what they think is in afamiliar-looking box of candies (responding ‘‘candies”),and are then shown that the box contains pencils. Childrenare then asked what they thought was in the box before thebox was opened, and 3-year-olds (often) respond ‘‘pencils.”As Gopnik and Astington (1988) commented, theyappeared to overwrite their first memory with the later‘‘correct” or ‘‘real” information. When a conflict existsbetween what one thought was the case and what the evi-dence shows to be reality it is certainly adaptive to overwritethe former with the latter in one’s permanent knowledgesystem. It seems that this is what young children are pre-pared to do. In some cases, however, it is better to keep bothalternatives in mind – when they do not conflict and wheneach might be useful but under different conditions; thisdoes not appear to be what young children are prepared for.

4.2. Mimesis, recall, representation

The relation of the findings from delayed imitation stud-ies with infants to Donald’s (1991) theory of mimesis as aprerequisite for the evolution of language is striking (Nel-son, 1996). Mimesis refers here to forms of imitation thatreflect the ability to recall and replicate prior actions ormodels voluntarily. In Donald’s (1991) theory representa-tion of memory contents in voluntary recall is a character-istic of mimetic functioning, which appeared in thehominid line 1½ million years before the appearance ofHomo sapiens. In the developmental scheme, mimesisemerges in the toddler period through imitation and playthat first enable the child to make public representationsof what had been strictly private mental contents in basicmemory. In agreement with Donald, I believe that this firstexternalization of individual mental content is a major steptoward the evolution and development of distinctivelyhuman minds.

As already stressed with respect to infant memory, basicmemory in any embodiment is private, unshareable. Otherpeople’s actions may be observed and retained in thechild’s memory as any other perceptually-derived meaningis. But others cannot directly implant information, mem-ory, or knowledge into the child’s own system; demonstra-tion and imitation – social learning – are strictly limited inthis respect. New knowledge or beliefs that are attainedthrough perception and action remain subjective and pri-vate, even though they may have been modeled on orinferred from someone else’s actions. Others’ perceptions,knowledge and beliefs are closed to the child’s system.Thus, in mimetic cognition, exchange of meanings in eitherdirection from or to the self is strictly limited.

4.3. Language and memory in development

Language used in the second year, typically only singlewords, clearly has an effect on retention of a memory,although its exact mechanism is unclear. The delayed imi-tation evidence from toddlers indicates that verbalizingaspects of an event at the time of delayed recall (but notat the time of the experience) increases the length of reten-tion of the memory (Bauer, 2006). However, other studieshave found that only children who knew words for theprops in an event experienced at 2 years could recall theevent 2 years later (Simcock and Hayne, 2002). These earlyeffects of language on memory seem to imply that wordsare used as markers or reminders rather than being animportant component of the event memory itself.

An important point in a child’s mastery of languageoccurs when language becomes an alternative system ofrepresenting the world such that the child can understandsomeone else’s account of an event – a story, or a recount-ing of something that happened, shared or not. At thispoint, language can serve as an alternative medium toactive experience in entering memory. In this regard, agreat deal of research has documented the positive effectsof conversations about the past on children’s growing abil-ity to recall episodes in detail and within a narrative frame-work that includes setting, mental states, highpoints, causal

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strings, and evaluations (Reese et al., 1993; Fivush andNelson, 2006). Such practices introduce the child to waysof representing their own experiences as meaningful wholesthat can be shared with someone else. Children of motherswho elaborate more on the child’s memory accounts pro-vide more details and story components on their own whenrecounting memories as much as two years later. Theweight of the evidence supports the conclusion that experi-ence with the practice of talking about what the child hasexperienced in the past, in terms of narratives about selfand other in specific times and contexts is associated withthe child’s early engagement in episodic remembering. Dif-ferent strands of research also indicate that children’s con-cepts of self and of relative time (past–present–future)advance with their engagement in memory talk (Nelsonand Fivush, 2004).

In addition, cross-cultural studies show differences in thecharacteristics of parent-child ‘‘memory talk” as well asrelated differences in the age and type of memories pro-duced by children and adults (Fivush and Nelson, 2004;Wang, 2003). Further, deaf children of hearing parents,whose parents typically do not have sign language and thusdo not engage in conversations about past events, are latein forming personal episodic memories. Children with aut-ism syndrome, even those with adequate language skill, donot engage in social exchange of memory talk, and theytend to remember few episodes from the personal past;memories that are recalled are composed of incomplete bitsand pieces typical of younger children (Goldman, 2003). Itis through social exchanges in conversations about pastevents that the different experiences of self and other arehighlighted as well as the distinctiveness of the past in con-trast to the present.

4.4. The problem of source

We can understand the effects of language practices onlong-term memory in the early childhood years in terms ofa new and distinctly different avenue of experience openedup to memory. But this is an avenue with pitfalls built intoit. Opening memory – previously restricted to the experienceof the self – to verbal accounts of others is of obvious impor-tance to human cognition, but it is also obviously less trust-worthy than personal experience. One’s own perceptualexperience may be flawed, but subjectively it is a solid sourceof knowledge. Indeed, the drawbacks to an ‘‘open socialmemory” for both adults and children is revealed throughresearch on suggestibility and source confusions. In fact, asingle weakness – omission of source information – appearsto explain both forms. Young children’s suggestibility isrelated to the now well-established effects on later recall inadults of post-event misleading information (Loftus,2004). Adults often incorporate misleading ‘‘facts” into theirmemories, and three- to five-year-old children appear to beeven more disposed to incorporate parts of episodes heardfrom another or even to adopt the whole episode as theirown memory (Ceci and Bruck, 1993). Suggestibility is a

threat to accurate memory at any age, but is especially sofor children of 5 years and under. Source errors are impli-cated inasmuch as the person remembering could rejectthe misleading information by noting which informationhad its source in the direct experience of the event and whichin a report or question from someone else. ‘‘Marking” thememory as to source appears to be a good insurance policyagainst unreliable information.

However, young children appear to ignore source infor-mation of all kinds (Roberts and Blades, 2000). For exam-ple, they fail to note how they came to know the location ofobjects in an experiment, through viewing, hearing aboutit, or guessing. Remarkably, 4-year-old who are told anovel fact and are asked minutes later how they came toknow it are typically unable to say that someone told them;instead many will claim that they have always known it.These errors are similar to suggestibility effects in that chil-dren do not distinguish between information that arrivesfrom someone else through language and its source in theirown experience, once both have entered into memory.

It is not surprising that the memory system in the youngchild appears to be undifferentiated as to source given thatprior to language the system is confined to individualunmediated direct experience. When language is used toimpart knowledge it crosses the internal–external boundaryin a new way; one cannot see another’s experience, but onecan understand another’s linguistic account of experience.What seems puzzling is that linguistic accounts are notapparently distinguished from experience itself. Thisimplies that, once learned, language and direct experienceenter in the same way into the memory system. Recall thatin basic memory old knowledge is overwritten when newinformation comes in that conflicts with the old; the systemis updated. Together, these facts – adaptive overwritingand undifferentiated sources – account for suggestibilityeffects: for the child, what someone says happened has asmuch validity as what was observed to happen, andbecause it comes later in time it takes precedence, overwrit-ing the previous account.

4.5. The disadvantages of the private and undifferenti-ated system compared to the later dual mode system areseveral: there is no distinction made between self and othersources, no specificity of self-knowing or autonoesis, thusno episodic system. Moreover, there is no need for makinga distinction about when in the past something happenedbecause the past can be overwritten when new informationcomes in; old information is then discarded. Episodes fromthe past have no ‘‘keeping” power – they are not held ontowhen life progresses to a new set of experiences. Theseweaknesses of children’s memory system are endemic tobasic memory and become apparent when it comes in con-tact with reports from others.

5. Conclusion

Development of a mature, more complex, time-orientedepisodic memory system emerges in conjunction with the

K. Nelson / Journal of Physiology - Paris 101 (2007) 223–229 229

establishment of a self/other memory distinction. A quali-tative change takes place in the memory system that differ-entiates episodic memory on the basis of its source,establishes the distinctive qualities of episodic memory,and restricts re-writing of old memories enabling the indef-inite retention of meaningful autobiographical memories.These developments require that children become con-scious of when information should be discarded or over-written and when conflicts in accounts should be retainedfor further consideration. Current research indicates thatdevelopments of these kinds take place around the age of5 and 6 years and are related to other developments insocial cognition (Nelson, 2007).

Thus far the question of extending memory in the direc-tion of social–cultural influences has been only obliquelyaddressed, but it is implied by the fact the once languageis acquired its influence is unbounded. Language is not sim-ply a code, it is a socially and culturally shared symbol sys-tem that enters into the neural and mental establishmentand organization of learning and memory. The proposalbriefly presented here rests on the recognition that oncelanguage is acquired by the child memory and all othercognitive processes must and do adapt to its power andto the contents and organization that it makes available.Linguistic minds are different from non-linguistic minds.This proposition does not rest, however, on the so called‘‘language module” (Chomsky, 1965) (actually a grammarmodule) but on the social and cultural functions and effectsof language on the mind as described here. That said, itshould be noted that non-linguistic human minds (e.g.,deaf adults without sign language) experience the worldunder the same general conditions that others do (seeFig. 1). They are, however, differently accessible to thesocial and cultural narrative and conceptual resources ofothers, and their brains and minds can be expected to beorganized differently as well (Donald, 1991, 2001). Theseconsiderations, and the developments described here, implythe need for more inter-disciplinary research on braindevelopment and linguistic and cognitive development inthe early years of life to understand the process by whichlanguage takes over the mind and memory of almost allhuman children and adults.

References

Bauer, P.J., Hertsgaard, L.A., Dow, G.A., 1994. After 8 months havepassed: long-term recall of events by 1-to 2-year-old children. Memory2, 353–382.

Bauer, P.J., 2006. Event memory. In: Kuhn, D., Siegler, R. (Eds.),Cognition, perception and language, second ed., . In: Handbook ofChild Psychology, vol. 2 John Wiley & Sons, Inc., New York, pp. 373–425.

Ceci, S.J., Bruck, M., 1993. Suggestibility of the child witness: a historicalreview and synthesis. Psychol. Bull. 113, 403–439.

Chomsky, N., 1965. Aspects of a Theory of Syntax. MIT Press,Cambridge MA.

Donald, M., 1991. Origins of the Modern Mind. Harvard UniversityPress, Cambridge MA.

Donald, M., 2001. A Mind So Rare: The Evolution of HumanConsciousness. Norton, New York, NY.

Fivush, R., Nelson, K., 2004. Culture and language in the emergence ofautobiographical memory. Psychol. Sci. 15, 573–577.

Fivush, R., Nelson, K., 2006. Parent-child reminiscing locates the self inthe past. Brit. J. Dev. Psychol. 24, 235–251.

Goldman, S., 2003. Unpublished Ph.D. Diss., City University of NewYork, New York, NY.

Gopnik, A., Astington, J.W., 1988. Children’s understanding of repre-sentational change in its relation to the understanding of false beliefand the appearance-reality distinction. Child Dev. 59, 26–37.

Loftus, E.F., 2004. Memories for things unseen. Curr. Dir. Psychol. Sci.13, 145–147.

McDonough, L., Mandler, J.M., 1994. Very long-term recall in infants:infantile amnesia reconsidered. Memory 2, 339–352.

Miller, G.A., 1956. The magical number seven, plus or minus two: somelimits on our capacity for processing information. Psychol. Rev. 63,81–97.

Nelson, K., 1986. Event Knowledge: Structure and Function in Develop-ment. Lawrence Erlbaum Assoc., Hillsdale NJ.

Nelson, K., 1993. The psychological and social origins of autobiographicalmemory. Psychol. Sci. 4, 1–8.

Nelson, K., 1996. Language in Cognitive Development: The Emergence ofthe Mediated Mind. Cambridge University Press, New York.

Nelson, K., 2007. Young Minds in Social Worlds: Experience, Meaning,and Memory. Harvard University Press, Cambridge, MA.

Nelson, K., Fivush, R., 2004. The emergence of autobiographicalmemory: a social cultural developmental theory. Psychol. Rev. 111,486–511.

Oyama, S., Griffiths, P.E., Gray, R.D. (Eds.), 2001. Cycles of Contin-gency: Developmental Systems and Evolution. MIT Press, CambridgeMA.

Perner, J., 2000. Memory and theory of mind. In: Tulving, E., Craik,F.I.M. (Eds.), The Oxford Handbook of Memory. Oxford UniversityPress, New York, NY, pp. 297–312.

Reese, E., Haden, C.A., Fivush, R., 1993. Mother-child conversationsabout the past: relationships of style and memory over time. CognitiveDev. 8, 403–430.

Roberts, K.P., Blades, M. (Eds.), 2000. Children’s Source Monitoring.ERlbaum Assoc., Mahwah, NJ.

Rovee-Collier, C., Hayne, H., 2000. Memory in infancy and earlychildhood. In: Tulving, E., Craik, F.I.M. (Eds.), The Oxford Hand-book of Memory. Oxford University Press, New York, NY, pp. 267–279.

Simcock, G., Hayne, H., 2002. Breaking the barrier? Children fail totranslate their preverbal memories into language. Psychol. Sci. 13, 225–231.

Smith, L.B., Thelen, E., 2003. Development as a dynamic system. TrendsCogn. Sci. 7 (8), 343–348.

Terrace, H.S., Metcalfe, J. (Eds.), 2005. The Missing Link in Cognition:Origins of Self-Reflective Consciousness. Oxford University Press,New York.

Thelen, E., Smith, L.B., 1994. A Dynamic Systems Approach to theDevelopment of Cognition and Action. MIT Press, Cambridge, MA.

Tulving, E., 2005. Episodic memory and autonoesis: uniquely human? In:Terrace, H.S., Metcalfe, J. (Eds.), The Missing Link in Cognition.Oxford University Press, New York, NY, pp. 3–56.

Wang, Q., 2003. Infantile amnesia reconsidered: a cross-cultural analysis.Memory 11, 65–80.