Exploring Memory's Role in Self-awareness: Episodic and Semantic Memory, Study notes of Psychology

Download Exploring Memory's Role in Self-awareness: Episodic and Semantic Memory and more Study notes Psychology in PDF only on Docsity! KLEIN ET AL.COMPONENTS AND DISORDERS OF AUTOBIOGRAPHICAL MEMORY A THEORY OF AUTOBIOGRAPHICAL MEMORY: NECESSARY COMPONENTS AND DISORDERS RESULTING FROM THEIR LOSS Stanley B. Klein, Tim P. German, Leda Cosmides, and Rami Gabriel University of California, Santa Barbara In this paper we argue that autobiographical memory can be conceptualized as a mental state resulting from the interplay of a set of psychological capaci- ties—self-reflection, self-agency, self-ownership and personal temporal- ity—that transform a memorial representation into an autobiographical personal experience. We first review evidence from a variety of clinical do- mains—for example, amnesia, autism, frontal lobe pathology, schizophre- nia—showing that breakdowns in any of the proposed components can produce impairments in autobiographical recollection, and conclude that the self-reflection, agency, ownership, and personal temporality are individually necessary and jointly sufficient for autobiographical memorial experience. We then suggest a taxonomy of amnesic disorders derived from consideration of the consequences of breakdown in each of the individual component processes that contribute to the experience of autobiographical recollection. THE SELF Scholarly investigations of the self can approach their subject matter from either an ontological or an epistemological perspective. The former examines the status of the self as an object of scientific and philosophical inquiry, attempting to ascertain what the self is. Theorists pursuing the ontology of self immediately find themselves immersed in a host of thorny issues about mind and body, subject and object, object and pro- 460 Social Cognition, Vol. 22, No. 5, 2004, pp. 460-490 We wish to thank John Tooby and Judith Loftus for their contributions to the ideas ex- pressed in this article. Correspondence may be addressed to Stan Klein, Department of Psychology, University of California, Santa Barbara, CA 93106; E-mail: Klein@psych. ucsb.edu. cess, the homunculus, free will, self-awareness, and other puzzling mat- ters (e.g., Bermudez, 1998; Cassam, 1994; Dalla Barba, 2002; Flanagan, 2002; Gallagher & Shear, 1999). The enduring nature of these problems has led some to question whether a conceptual understanding of the self is possible in practice (e.g., Olson, 1999) or in principle (e.g., McGinn, 1989). Although deeply interested in the complex issues raised by the prob- lem of ontology, our concern in this article is with first-person epistemol- ogy—how we come to know who and what we are. We start by taking the existence of self as an undeniable fact of human first-person experi- ence. Despite its problematic nature as an object of analysis, the self, as Descartes famously observed (1637/1970), is beyond doubt—it is a per- sonal truth given by virtue of its direct phenomenological acquaintance. But what is the basis of this acquaintance? In what ways do we come to know ourselves? How do we know we possess some features or charac- teristics but not others? Not only are these important questions, they may be analytically prior to an analysis of what the self is. As Strawson notes, the “sense of the self is the source in experience of the philosophi- cal problem of the self. So the first thing to do is to track the problem to this source in order to get a better idea of what it is” (Strawson, 1999, p. 2). Questions about first-person epistemology have long been a focus of scholarly inquiry. Much of this interest has been directed toward under- standing the part played by memory in the experience of self (e.g., Green- wald, 1981; Grice, 1941; James, 1890; Kihlstrom & Klein, 1994; Klein, 2001; Klein, Loftus, & Kihlstrom, 1996; Locke, 1690/1731; Shoemaker, 1963; Singer & Salovey, 1993; Snygg & Combs, 1949). The basic idea is that one’s sense of self depends, in a fundamental way, on memories of one’s past experiences and the capacity to call those experiences to mind. One of the earliest proponents of this view, John Locke (1690/1731), maintained that a person’s identity, which is to say his or her selfhood, extends to that por- tion of his or her past he or she can remember. Along similar lines, Grice (1941) argued that the self is constructed from the recollection of personal experiences and, therefore, “is to be defined in terms of memory” (p. 340). The view that the sense of self arises from memory alone may be too extreme. In this article, we discuss some of the additional computational machinery that may be necessary for memory to serve as a basis for self-knowledge. Our goal is to provide an initial step toward mapping some of the psychological processes needed to transform a memory trace into an autobiographical memorial experience. COMPONENTS AND DISORDERS OF AUTOBIOGRAPHICAL MEMORY 461 DISTURBANCES OF THE COMPONENTS OF AUTOBIOGRAPHICAL MEMORY SELF-REFLECTION Disturbances in higher-order cognitive function often accompany frontal lobe pathology. Although symptoms may vary both with the nature and location of the damage (for reviews, see Blumer & Benson, 1975; Miller & Cummings, 1999; Stuss & Benson, 1986), a consistent and prominent pathology consists in a reduced capacity to engage in self-reflection (e.g., Ackerly & Benton, 1947; Brickner, 1936; Macmillan, 1986; Stuss, 1991). In line with these clinical findings, re- cent neuroimaging studies suggest that the capacity to self-reflect de- pends critically on structures located in the frontal lobes (e.g., Baron-Cohen et al., 1994; Kelley et al., 2002; Morin, 2002: Vogeley et al., 2001; see Stuss & Anderson, in press, for a review). Given our analysis of the relation between self-reflection and autobio- graphical self-knowledge, we should expect to find frontal lobe pathol- ogy accompanied by impairments of episodic memory. The literature suggests that this is often the case (e.g., Della Sala, Gray, Spinnler, & Trivelli, 1998; Della Sala, Laiacona, Spinnler, & Trivelli, 1993; Levine et al., 1998; Levine et al., 1999; Markowitsch et al., 1993; for a comprehen- sive review, see Wheeler, Stuss, & Tulving, 1995). By contrast, memory that does not require awareness of re-experiencing personal happenings from one’s past (e.g., procedural and semantic) typically is spared (e.g., Della Sala et al., 1993; Della Sala et al., 1998; Levine et al., 1998; Levine et al., 1999; Wheeler et al., 1997). Persons with autism also evidence limited capacity for self-reflection (e.g., Baron-Cohen, 1989, 1991; Baron-Cohen et al., 1994; Frith, 1989; Hobson, 1993; Jordan, 1989; Russell, 1996; Tager-Flusberg, 1992). Stud- ies have shown that, compared to normally developing children, chil- dren with autism have problems reflecting on their mental states (e.g., Baron-Cohen, 1995; Tager-Flusberg, 1992). Similarly, clinical descrip- tions of autistic patients frequently make mention of their inability to self-reflect (e.g., Baron-Cohen, 1989; Bishop, 1993; Hobson, 1993). Per- sons with autism also appear to have problems with episodic recollec- tion. Compared with nonautistic controls, autistic individuals perform significantly worse on tests of recall (e.g., Bennetto, Pennington, & Rog- ers, 1996; Boucher, 1981b; Boucher & Warrington, 1976; Ozonoff, Pen- nington, & Rogers, 1991; Tager-Flusberg, 1991), particularly when testing requires recollection of personally experienced events (e.g., Boucher, 1981a; Boucher & Lewis, 1989; Klein, Loftus, & Chan, 1999; Klein, Cosmides, Costabile, & Mei, 2002; Powell & Jordan, 1993) By con- 464 KLEIN ET AL. trast, they typically perform nearly as well as controls on tasks that rely on semantic and procedural memory (e.g., Ameli, Courchesne, Lincoln, Kaufman, & Grillion, 1988; Boucher & Lewis, 1989; Boucher & Warrington, 1976; Bowler, Mathews, & Gardiner, 1997; Goldstein, Minshew, & Siegel, 1994; Klein et al., 1999; Tager-Flusberg, 1985a, 1985b, 1991; Ungerer & Sigman, 1987; but see Klinger & Dawson, 1995). AGENCY AND OWNERSHIP Pathologies of personal agency/ownership are among the hallmark symptoms associated with schizophrenia (for reviews of schizophrenic symptomology, see David & Cutting, 1994; Frith, 1992). Disturbances in personal agency are reflected in symptoms such as delusions of control and thought withdrawal (e.g., Daprati et al., 1997l; Gallagher, 2000; Frith 1992, 1996). For example, patients suffering delusion of control experi- ence their own thoughts and actions as having been caused by an exter- nal agent rather than the self (e.g., Vogeley et al., 1999). Disturbances in the experience of personal ownership are reflected in symptoms such as thought insertion and auditory hallucinations (e.g., Frith, 1992; Vogeley et al., 1999). Thought insertion, for example, consists of patients dis- avowing ownership of their own thoughts, attributing them instead to an outside source (e.g., Frith, 1992). If personal agency and personal ownership are among the prerequi- sites for autobiographical self-knowledge, and if schizophrenia repre- sents a breakdown in these capacities, it follows that schizophrenics should experience impairments of episodic memory. A review of the lit- erature shows this to be the case (e.g., Bazin & Perruchet, 1996; Berthet et al., 1997; Feinstein, Goldberg, Nowlin, & Weinberger, 1998; Huron et al., 1995; Keri et al., 2000; Lussier, Stip, & Coyette, 1997; Rizzo, Danion, Van Der Linden, & Grange, 1996; Rushe, Woodruff, Murray, & Morris, 1999). Importantly, these impairments are disproportionately pronounced in comparison to other memory deficits in schizophrenia (e.g., Bazin & Perruchet, 1996; Huron et al., 1995; Lussier et al., 1997; Rushe et al., 1999), suggesting that episodic memory loss is not simply part of a pattern of general mental deterioration. THE SENSE OF PERSONAL TEMPORALITY Episodic memory differs from other forms of memory in that it alone en- ables one to mentally travel through subjective time to relive personal events from one’s past. If a precondition for “mental time travel” is the COMPONENTS AND DISORDERS OF AUTOBIOGRAPHICAL MEMORY 465 capacity to become aware of the temporal dimensions of one’s own ex- perience, it follows that an individual suffering impairments of personal temporality should find it difficult to experience declarative knowledge as part of his or her past. Although very few studies have examined the effects of pathologies of subjective temporality on memory, those that have generally are sup- portive. One source of evidence comes from the case of patient D.B., who suffered brain damage as a result of anoxia following cardiac arrest (Klein, Cosmides, Costabile, & Mei, 2002; Klein, Kihlstrom, & Loftus, 2002). Neuropsychological assessment of D.B.’s temporal orientation (Mini-Mental States Examination (MMSE); Cockrell & Folstein, 1988, and General Practitioner Assessment of Cognition ( GPCOG); Brodaty et al., 2002) showed severe disorientation with respect to the present. For example, he did not know the day of the week, the current year, or even his age. Additional testing revealed that D.B. was unaware that he had a past and unable to imagine what his experiences might be like in the fu- ture. Not surprisingly, D.B.’s episodic memory is severely impaired: he cannot consciously bring to mind personal experiences from any point in his past. A severe disturbance of temporality also is found in the case of patient K.C. (for reviews, see Tulving, 1985, 2002). For example, when asked by his physician what he did “before coming to where he is now, or what he did the day before, he says he does not know. When asked what he will be doing when he leaves ‘here,’or what he will be doing ‘tomorrow,’ he says he does not know” (Tulving 1985, p. 4). Although K.C. shows dis- turbances in his thinking about past and future, he can function in the present moment within some kind of psychologically constructed event boundary. He is able to play a hand of bridge, for example, as long as nothing interrupts the bidding. Yet he forgets what happened if a phone rings in midplay. K.C.’s amnesia is profound: He is unable to con- sciously bring to mind a single personal experience from any point in his past. Admittedly, while these findings support the hypothesis that disrup- tions of personal temporality compromise episodic memory, they also could support the argument that impairments in episodic recollection result in pathologies of personal temporality. However, a review of the literature reveals that episodic memory loss is not necessarily associated with impairments of temporal consciousness. For example, patients with retrograde amnesia cannot remember their personal past, but they can remember events occurring after the brain trauma that left them am- nesic; other amnesic patients report other types of temporal gaps in their personal narrative. Yet there is no evidence to suggest that these impair- ments invariably lead to disruptions in the experience of the personal 466 KLEIN ET AL. within a temporal framework—are involved in the transformation of declarative knowledge into an autobiographical memorial experience. On this view, episodic retrieval—the generation of autobiographical memorial experiences—cannot occur unless all of these capacities are in- tact. Possessing an intact database of event memories is necessary for episodic retrieval, but it is not sufficient. Amnesia is the inability to retrieve episodic memories. When the data- base of event memories has been damaged, amnesia should occur. But if the view outlined above is correct, there should be several distinct amne- sic syndromes, each associated with damage to a different component of the system necessary for re-experiencing these autobiographical events. Even if the database of events is intact, amnesia could result from damage to the ability to self-reflect, damage to the machinery that creates a sense of personal agency/ownership, or damage to the sense of temporality. Brain trauma, disease, or developmental disorders could, in principle, damage one of these components while leaving the others intact. Different amne- sic syndromes should result, each characterized by a different pattern of episodic memory impairment, depending on which component (or set of components) is damaged (e.g., Klein, Cosmides, Tooby, & Chance, 2002). Before discussing these predictions, we first consider whether self-re- flection, personal agency/ownership, and temporality reflect the opera- tion of a single system, or can be considered functionally distinct components, capable of independent breakdown. METAREPRESENTATIONS AND AUTOBIOGRAPHICAL SELF-KNOWLEDGE With the rise of the cognitive sciences, various components of the self be- gan to be conceptualized as computational systems and the databases they access. For example, research on theory of mind reframed the abil- ity to “reflect upon the self” as the ability to form metarepresentations, which are representations about other mental representations, whether one’s own or others’ (Baron-Cohen, Leslie & Frith, 1985; German & Leslie, 2000; Leslie, 1987). In Leslie’s (1987, 2000b) account, these M-rep- resentations are data files with a particular format, including slots for an agent (e.g., “I,” “You,” “Dad,” “Ellen”), that agent’s attitude toward a proposition (e.g., “believe,” “doubt,” “hope,” “remember”), and an em- bedded proposition (e.g., “it is raining,” “I became anxious at the zoo,” “I thought that modern art is ugly”) (see Figure 1). Because the agent can be the self and the embedded proposition can it- self be a metarepresentation about the self, this data format allows the formation of self-reflective representations, such as “I remember that I COMPONENTS AND DISORDERS OF AUTOBIOGRAPHICAL MEMORY 469 became anxious at the zoo” or “I doubt that I thought that modern art is ugly.” On this view, English expressions of this kind are generated by at- taching lexical items to data files in the language of thought: M-repre- sentations whose slots are filled in as follows: [Agent: Self]-[Attitude: remember]-[Proposition: I became anxious at the zoo] and [Agent: Self]-[Atti- tude: doubt]-[Proposition: ([Agent: Self]-[Attitude: thought]-[Proposition: modern art is ugly])]. M-REPRESENTATIONS AND SEMANTIC MEMORY According to Leslie (1987, 1994a, 2000a), storing a proposition in an M-representation decouples it from semantic memory. Decoupling pre- 470 KLEIN ET AL. Self? Harry? Mom? Attitude slot remember? doubt? believe? I pretended to be sick I sang in the park Harry made me mad Proposition slot event Agent slot FIGURE 1. Hypothesized data format for the M-representation, consisting of three slots and the links between them (after Leslie & Thaiss, 1992). The M-representation is a “file” in the language of thought that represents information about an agent (self, Harry, Mom); the agent’s mental state (i.e., propositional attitude: remember, hope, believe…); and a representation of a state of affairs that the agent remembers, doubts, believes, etc. When information is represented in this data format it is “decoupled” from semantic memory; that is, inferences can be made about the content of the agent’s mental states without them conflicting with or being stored as “true” in se- mantic memory (Leslie, 1987, 1988). Complementary mental machinery inserts the appropriate concept into each slot, resulting in representations—some autobio- graphical—such as [Self]-[remembers]-[I sang in the park]. It remains an open ques- tion whether the proposition slot is restricted to propositional representations or whether it can also take event memories that have quasi-perceptual qualities. COMPONENTS AND DISORDERS OF AUTOBIOGRAPHICAL MEMORY 471 vents the corruption of databases in semantic memory while still allow- ing useful counterfactual inferences to be drawn. On this view, the purpose of semantic memory is to store information about the world that is true—or at least consistent enough with reality to effectively guide behavior. This encyclopedia of world knowledge will be less use- ful to the extent that it becomes corrupted with false or misleading infor- mation. Leslie argues that the specialized data format of the M-representation has an important function: It allows useful inferences to be made while preventing false information from being stored as true in semantic memory. For example, let’s say you know (as a matter of se- mantic knowledge) that Ellen’s class is on Tuesday, but you hear her say that it is on Wednesday. By embedding her stated belief —Ellen’s class is on Wednesday —in the M-representation Ellen believes Ellen’s class is on Wednesday, you can make inferences about Ellen’s behavior (e.g., if no one tells her otherwise, Ellen will miss her class) without becoming con- fused as to the true state of affairs. An architecture capable of decoupling is necessary for any form of counterfactual or suppositional thinking; without it, we would be incapable of hearing fiction, making plans, or generating as-yet-unconfirmed hypotheses without becoming delu- sional. Delusions are false beliefs: Without decoupling mechanisms that keep some information distinct from the semantic knowledge database, stories, plans, speculations, pretenses, and falsehoods would be stored as—and therefore confused with—real events and facts (for discussion and extensions, see Cosmides & Tooby, 2000). M-REPRESENTATIONS AND SELF-REFLECTION The computational machinery that produces metarepresentations ap- pears to come on-line at about 18 months, when toddlers begin to pro- duce and understand pretend play (e.g., Baron-Cohen, 1995; Leslie, 1987), and it can be selectively impaired. For example, individuals with autism understand that photos—physical representations of the world—can misrepresent the facts, but have difficulty understanding that beliefs—mental representations about the world—can do the same (e.g., Charman & Baron-Cohen, 1995; Leslie & Thaiss, 1992). Autism, it has been argued, disrupts the development of metarepresentational ma- chinery, either directly (e.g., Baron-Cohen, 1995, 2000; Baron-Cohen, Leslie, & Frith, 1985; Frith, Morton, & Leslie, 1991; Leslie, 2000b) or per- haps as a result of disruptions to components responsible for detection and representation of agency based on perceptual cues (e.g., Adolphs, Pears, & Siden, 2001; Baron-Cohen, 1995; Dawson, Meltzoff, Osterling, Rinaldi, & Brown, 1998; Klin, Jones, Schultz, Volkmar, & Cohen, 2002; ership. Below, we discuss the various types of amnesia and other disturbances of episodic memory that such disruptions could cause. SPECIES OF AMNESIA Inspection of Figure 1 shows that the M-representation is composed of (at least) three subcomponents—the agent slot, attitude slot, and propo- sition slot—as well as the links between them. This suggests that there are a number of distinct ways in which this data file format can break down: 1. Any of the three slots could be damaged. 2. Any (or all) of the links between the slots could be damaged. 3. The machinery that fills the slots could be damaged. 4. Some (or all) of the concepts that can fill the slots can be damaged. For example, disruption of the agent slot or the machinery that fills it would result in a disruption in the sense of personal agency/ownership. Disruption of the attitude slot would disconnect agents from the content of their thoughts. The failure of a particular mental state concept to de- velop could result in a disconnection syndrome that disrupts the forma- tion of some M-representations but not others. Failure of decoupling (resulting from any of the above) could create delusions. Machinery that creates temporality, in conjunction with intact M-representations, would create a different pattern entirely. In this view, episodic memory impairment, including amnesia, would not be a single disorder caused by the loss of a database of event memo- ries, but a heterogeneous set of disorders, each with a different symptom profile. As a thought experiment, we consider what kinds of impair- ments in autobiographical self-knowledge would result if there were damage to only one of the components hypothesized to contribute to the experience of an episodic memory. 1. Damage to the database of events. Classic amnesic syndrome is usually assumed to involve damage to a database of episodic event memories (e.g., Cremak, 1984; Parkin, 1997; Tulving, 1983). Head trauma, for ex- ample, can cause a retrograde amnesia: The person cannot remember events that happened before the accident, but has no trouble remem- bering events that happened afterward. In these cases, there is no obvi- ous disturbance in the ability to self-reflect, in the sense of personal agency/ownership, or in temporality (events occurring after the acci- dent are remembered in correct temporal order). That is, the machinery 474 KLEIN ET AL. to form M-representations appears entirely intact, along with the sense of temporality, and there are no impairments to other memory systems (working memory, semantic memory, procedural memory, the per- ceptual-representational system; see Klein et al., 2002, for a review). This profile of spared and impaired abilities is consistent with the no- tion that a portion of a database of event memories has been destroyed. This is the profile that most often comes to mind when one thinks of ep- isodic amnesia. But the perspective above suggests that there will be other forms, associated with damage to the other systems that cooperate in creating autobiographical self-knowledge. 2. Disruptions of the agent slot of the M-representation. Imagine that the ma- chinery that fills in the agent slot is disrupted. The agent slot provides a source tag: It specifies which individual—the self or someone else—re- membered, believed, doubted, etc., the proposition or event in question. These source tags might be important both at encoding and at retrieval. If the agent tags get scrambled, then thoughts generated by the self will be attributed to other individuals and vice versa. Schizophrenia (along with other dissociative disorders) is particu- larly interesting in this regard. Schizophrenia disrupts the experience of personal agency/ownership, without necessary affecting one sense of temporality. When an individual with schizophrenia “hears voices,” they are not experienced as in the outside world: The thoughts are “heard” inside the individual’s own head. As the Friths (e.g., Frith, 1992) have argued, this is consistent with the hypothesis that there has been damage to the machinery that fills the M-represen- tation’s agent slot (or damage to the slot itself): Thoughts, intentions, and memories generated by the individual are attributed to other agents during positive symptoms of schizophrenia, or to no agent at all, as the disease progresses and periods of negative symptoms become longer and longer. As the machinery that inserts agents into the agent slot breaks down—or as the slot itself breaks down—all thoughts would be experi- enced noetically, none autonoetically. This means that opinions and be- liefs, whether true or false, would be retired to semantic memory as true, corrupting the individual’s database of world knowledge with false or misleading information (e.g., Cosmides & Tooby, 2000; Leslie, 1987, 1994a). It also means that the person would appear to have an episodic amnesia: At retrieval, events that happened to the individual would be experienced as facts of the world, not as personal memories. As in classical amnesia, there would be no damage to working mem- ory, procedural memory, or the perceptual-representational memory (e.g., Klein et al., 2002). However, when memory traces of events are re- COMPONENTS AND DISORDERS OF AUTOBIOGRAPHICAL MEMORY 475 trieved in an M-representation to produce an episodic memory experi- ence, the agent slot might be incorrectly filled. This could produce the following profile of episodic memory effects: (a) If another agent is inserted rather than the self, then an event expe- rienced by the schizophrenic individual would be recalled as hav- ing happened to someone else; one would experience oneself as telepathically “remembering” someone else’s memories. Inten- tions generated by the individual will be experienced as having been generated by someone else: Someone else will seem to con- trolling one’s actions, and this “external control” will be remem- bered as such. (b) If the self is inserted inappropriately, one might “remember” having participated in events that are fictional or were described to one by others. After reading The Lord of the Rings or seeing the movie, one might vividly “remember” visiting the Shire with Frodo, a memory trace that was not derived from first-person experience. (c) If no agent was inserted into the agent slot, thoughts and memo- ries originating in the individual will not be experienced as first-person knowledge, that is, as ideas or events that were ex- perienced directly by the individual. They will be experienced instead as facts about the world. In this situation, the person will have difficulty recalling any episodes as having happened to the self. Moreover, thoughts and opinions will be stored in semantic memory (whether true or not). The individual’s database of knowledge will slowly accumulate false information and be- come increasingly discrepant with the knowledge of others. Im- pairments to the database of nonpersonal semantic knowledge is relatively rare in classic amnesic syndrome due to head injury, but these do occur in schizophrenia (McKenna, Mortimer, & Hodges, 1994). The first two effects, (a) and (b), are typical when an individual with schizophrenia is experiencing positive symptoms; they make the per- son’s autobiographical self-knowledge appear false or delusional. But as the disease progresses untreated, and periods of so-called neg- ative symptoms predominate, the profile is more consistent with the situation described in (c), where no agent is inserted at recall. Eventu- ally the person seems simply amnesic, with some distortions in se- mantic knowledge. An individual with schizophrenia need not be disoriented as to time. However, their personal narrative might have holes (due to the amnesia). Moreover, if the content of memory traces is used to reconstruct the temporal order of past events (e.g., remem- 476 KLEIN ET AL. cluding goal states or perceptual states. Such a person would be totally unable to remember a personal past. Although patients with Alzhei- mer’s disease do seem to have a self-as-agent concept in the early and middle stages of the disease (e.g., Klein, Cosmides, & Costabile, 2003), the very latest stages, in which the patient does not seem able to remem- ber or even identify family members or themselves (e.g., Hehman, Ger- man, & Klein, in press), may involve a breakdown in these agent concepts. There may be certain drugs that temporarily disrupt the Self agent concept. Although it is difficult to know how to analyze reports of phe- nomenal experiences, the hallucinogen Dimethyltryttamine (DMT) sometimes is experienced as breaking down any sense of a self as exist- ing in space and time (e.g., Shanon, 2002; Strassman, 2001). Moreover, temporarily attaining this experiential state is the goal of certain meditative traditions. 5. Disruptions of temporality. Imagine a person who has intact M-repre- sentations, intact agent concepts, and an intact database of event memo- ries. However, the machinery of temporality is disrupted, such that the person cannot order retrieved memories with respect to time, nor distin- guish past from present. An individual with this pattern of impaired and spared abilities would present a distinctive profile of episodic memory impairment. Such an individual might be able to remember events from a personal past, but would be deeply confused as to when things hap- pened. Events that happened years ago might be remembered as having happened last week, and vice versa. The amnesic patient D.B. has no obvious impairments with regard to self-reflection, personal agency, or personal ownership (e.g., Klein, Rozendal, & Cosmides, 2002). He did, however, suffer severe pathology of personal temporality (and may have also sustained some damage to his da- tabase of event memories). In response to prompts, he usually was unable to recall episodes from a personal past. On occasion, however, he did accu- rately recall events, but with wildly incorrect time assignments (Klein, Lof- tus, & Kihlstrom, 2002). For example, D.B. recalled having visited with friends from the East Coast during the prior week, an event that his daugh- ter reports happened 41 years ago. And he incorrectly “remembered the fu- ture”: in the past, he had driven down the coast with his parents (now dead), yet he reported this as a future plan “I will be driving down the coast with my parents soon”. Time confabulations of this kind also occurred in K.R., who had midstage Alzheimer’s disease (Klein et al., 2003). 6. Disruptions of inhibitory control. Although the M-representation and decoupling may be necessary for orderly self-reflection, other mecha- COMPONENTS AND DISORDERS OF AUTOBIOGRAPHICAL MEMORY 479 nisms are also required. For example, Leslie (2000b) argues that believ- ing what is true is a prepotent response, which must be inhibited in order to form an M-representation that reflects the fact that someone else holds a false belief. The ability to coordinate action and inhibit pre- potent responses increases as the frontal lobes mature (e.g. Gerhstadt, Hong & Diamond, 1994) and decreases with frontal lobe damage (e.g., Archibald, Mateer, & Kerns, 2001; Lhermitte, 1983). Leslie and col- leagues (German & Leslie, 2000; German & Nichols, 2003; Leslie, 1994b, 2000b; Leslie, German & Pollizi, in press; Leslie & Pollizi, 1998; see also Bloom & German, 2000) propose that inhibitory control must be present, alongside M-representations, for children to calculate cor- rectly the contents of false beliefs (see also Carlson & Moses, 2001; Carlson, Moses & Breton, 2002). This implies that damage to inhibitory control could result in another species of episodic memory impairment, even when metarepresentational machinery, temporality, and a database of events is intact. A person who lacks inhibitory control but nothing else might be able to retrieve episodic memories but unable to weave them together into a coherent narrative of his or her life story (e.g., Young & Saver, 2001). As the semantic content of one retrieved episode cues some other thought or episode, the episodes would come tumbling out one after the other in a disorderly way. Remembering an episode that occurred yes- terday might cue the content of an episode from childhood, which in turn cues an episode from last year, which cues an episode from adoles- cence, and so on. In each case, the individual would be able to accurately report when the event happened (in childhood, adolescence, adulthood, etc.). However, the individual would have great trouble telling the story of his or her life, of stringing the events of his or her personal past to- gether into a coherent, temporally ordered narrative life that another person could follow. 7. Damage to multiple systems. One problem with neurological evidence, from the investigator’s point of view, is that disease, developmental dis- orders, or brain damage often impair multiple mechanisms. For exam- ple, persons with frontal lobe damage may show disturbances in personal temporality (although not to the degree evidenced by patients K.C. and D.B.; for review, see Damasio, 1985; Robinson & Freeman, 1954); patients with autism sometimes evidence a diminished sense of personal agency and ownership (e.g., Bosch, 1970; Hobson, 1993); and schizophrenics may eventually develop difficulties with inhibitory control (Langdon et al., 2002). We have argued that a number of different cognitive components are necessary for autobiographical recollection, with its distinctive 480 KLEIN ET AL. phenomenological tone, to occur. Above, we tried to illustrate what pro- file of episodic memory impairment would occur if one—and only one—component of the several necessary for producing these recollec- tions were impaired. Although there may be few pure cases of this kind, our hope is that the taxonomy of amnesic disorders outlined above may help clinicians identify which cognitive components are damaged in any particular case, even if there is impairment to multiple mechanisms. There is a movement in clinical neuropsychology to move away from the characterization of “syndromes,” and instead focus on identifying which mechanisms are manifesting a dysfunction and thereby causing the symptoms observed (e.g., Frith, 1992). As Frith argues, this is what happens as medical science matures: What was first identified symp- tomatically (e.g., “produces a fever”) is eventually identified by the causal agent that produced the symptom (a strep infection, flu virus, meningitis, etc.). By identifying the causal agent, more effective treatments can be found. We offer the above taxonomy in the same spirit. It may be a mistake to think of “amnesia” or of “episodic memory impairment” as a single, overarching syndrome. Each species of amnesia may involve episodic memory impairment, just as different pathogens can all cause a fever. However, different profiles of episodic impairment may occur, depend- ing on which procedure(s) or databases are damaged. The same multiple-systems perspective suggests that results from brain imaging should be interpreted with caution. There have been a number of attempts to locate constructs such as “autobiographical mem- ory” in the brain (for reviews, see Nilsson & Markowitsch, 1999; Nyberg & Cabeza, 2000). But if the above perspective has any merit, then many different mechanisms participate in creating an autobiographical me- morial experience. To locate a database of events in the brain, it may not be sufficient to have the control task involve retrieval of semantic knowl- edge. Episodic recollection may require the activation of M-representa- tions in a way that semantic retrieval does not. 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