Verifying autobiographical facts

Cognition,

2

26 (1987) 39-58

Verifying

autobiographical

facts

M.A. CONWAY* MRC Applied Cambridge

Psychology

Unit,

Abstract The study of autobiographical memory has focused exclusively upon memories for specific experiences. Current models (Kolodner, 1983) postulate that autobiographical memories are represented in networks in which distinctive event features act as indices to related memories. But autobiographical knowledge, such as one’s name, drawn from a variety of frequently repeated experiences may be represented in memory independently of specific memories and so is unlikely to be indexed by event related information. Possibly, autobiographical facts are represented along with other types offactual knowledge (i.e., semantic knowledge). In order to investigate this a fact verification experiment was conducted in which subjects verified true and false autobiographical and semantic facts and were primed with semantic category names or with a neutral word. Verification of true autobiographical and semantic facts was fastest when primed with category names demonstrating that factual autobiographical information may be indexed by semantic information. Verification of false autobiographical facts was faster than verification of false semantic facts suggesting that the farmers’ lack of self-reference facilitated fast responding. Further evidence indicated that speed of verification of true and false autobiographical facts may, in part, be determined by the amount of related information already represented in memory. These findings indicate that not all autobiographical information may be represented in memories of specific experiences or indexed by event related information. It is argued that current models of autobiographical memory must take into account relations between factual autobiographical information and other types of factual information.

Recent research has reflected a growing interest in what has become known as ‘autobiographical’ memory, (i.e., memory for personally experienced events). Virtually all this research has required the retrieval of memories of *The author thanks Debra Bekerian for her helpful comments on various aspects of the research reported in this paper. This research was supported by the Medical Research Council of Great Britain. Reprint requests should be sent to: M.A. Conway, MRC Applied Psychology Unit, 15 Chaucer Road, Cambridge, U.K.

OOlO-0277/87/$6.50 0 1987, Elsevier Science Publishers B.V.

40

M.A. Conway

specific experiences (see e.g. Conway & Bekerian, in press; Crovitz & Schiffman, 1974; Reiser, Black, & Abelson, 1985; Robinson, 1976; Rubin, 1982). Autobiographical knowledge, however, may be represented in memory in different ways and not just in the form of memories of specific experiences. For example, personal information such as one’s name may be represented as an ‘autobiographical fact’ which is independent of any specific memory or set of memories. The purpose of the present study, then, was to examine the retrieval of autobiographical facts and to consider how such information might be organised in memory. Autobiographical

memories and autobiographical facts

One technique which has been recently employed to investigate autobiographical memory structure is that of priming (Conway & Bekerian, in press; Reiser et al., 1985). In these studies a subject is required to retrieve a memory to a specific cue and the cue is preceded by related information (the prime). Reiser et al. found that autobiographical memory retrieval was faster when contextual cues such as ‘Going to the cinema’ (called an ‘activity’) preceded the cue ‘Finding a seat’ (called a ‘general action’) compared to cue presentation in the reverse order (Finding a seat . . . Going to the cinema). Reiser et al. argue that retrieval was faster when the activity preceded the general action because specific memories are indexed in terms of sequences of contextually related activities. Retrieval was slower when the general action preceded the activity because general actions are associated with many contexts and, hence, additional processing must be undertaken to identify the target context. Reiser et al. propose that autobiographical memories are indexed by way of the knowledge structures employed in the original encoding and that these structures facilitate memory retrieval by making available likely features of a target memory. Conway and Bekerian (in press) conducted a series of primed autobiographical memory retrieval experiments. In these studies subjects retrieved memories to ‘personal history’ cues (e.g., Holiday in Italy), ‘semantic’ cues (e.g., Tennis) and ‘general action’ cues (e.g., Finding a seat). Prior to retrieval subjects were primed with related or unrelated information. Personal history cues were primed with ‘lifetime periods’ (e.g., Schooldays), semantic cues were primed with semantic category superordinates (e.g., Sports) and general actions were primed by ‘activities’ (e.g., Going to the cinema). Retrieval times to personal history cues were faster than retrieval times to all other cues and only lifetime period primes were found to speed retrieval. On the basis of these findings Conway and Bekerian proposed that autobio-

Autobiographical

facts

41

graphical memories may be indexed in terms of an abstracted personal history, or ‘life context’, which, in turn, indexes contextually based summaries of sets of memories (i.e., Holiday in Italy). These studies suggest that autobiographical memory may be highly structured and that abstract contextually related information may index specific memories. But what are ‘specific’ memories? Brewer (1986) points out that one distinguishing feature of ,autobiographical knowledge is that of self-reference. Moreover, autobiographical memories in addition to self-reference may be distinguished by their imaginal instantiation. That is to say that the types of memories selected for study typically (but not necessarily) involve some sort of image of the retrieved event. Related to this Conway and Bekerian found that cues relating to an individual’s life gave rise to the recall of memories of events high in personal importance and which were highly specific or vivid. Recall of memories to other types of cues were comparatively low in personal importance and specificity. Autobiographical memories are characterised by their self-reference, may be instantiated imaginally and are indexed by more abstract personal information. How, then, do autobiographical memories differ from autobiographical facts? Brewer argues that autobiographical facts are nonimaginal. For example, autobiographical information relating to one’s age may not be represented in memory in an imaginal form although, of course, this information may be closely associated with autobiographical memories. Autobiographical facts may, then, differ from autobiographical memories because of their nonimaginal nature. Furthermore, autobiographical facts may also differ from other types of facts in terms of their self-reference. For example, a semantic fact such as ‘cars have wheels’ may differ from an autobiographical fact such as ‘my car has a stereo’ because of the latter’s self-reference. Keenan and Baillet (1980) found that autobiographical facts relating to the self were responded to more quickly and better recognised than autobiographical facts relating to close friends and distant others. Keenan and Baillet also found that self related autobiographical facts were responded to more quickly than semantic facts. These authors argue that the elaborated memory representation of the self facilitates fast responding to information containing direct self-reference. An additional consideration, here, concerns TYPES of autobiographical facts. For example, a person who has only been to London once when answering the question ‘Have you ever been to London?‘, may draw upon information contained in autobiographical memories, whereas a person who regularly commutes to London may not access autobiographical memories in answering such a question. Linton (1982) makes a similar point when she observes that her own autobiographical memory for ‘meetings’ is restricted to the first and

42

M.A. Conway

last few meetings she attended and that other information concerning meetings was no longer tied to memories of specific meetings. Brewer (1986) similarly distinguishes between autobiographical facts drawn from single experiences and those drawn from many experiences. For present purposes the term ‘autobiographical fact’ will be employed to refer to memory for a frequently repeated experience (e.g., hearing/reading/writing one’s name). There is a further way in which autobiographical facts may differ from autobiographical memory and that is in terms of the way in which they are indexed in memory. If autobiographical facts are not associated with any specific memories then it seems unlikely that such facts could be directly indexed by information naming extended personal events (e.g., Holiday in Italy) or contextual activities (e.g., Going to the cinema). Moreover, autobiographical facts because they may be abstracted from many different experiences may not be associated with any specific contextual features other than the general context of the self. Autobiographical facts, as characterised here, are most similar to semantic factual knowledge. The two types of facts are similar in that they represent context-free information but differ in that autobiographical facts either represent, or may be indexed by, some form of self-reference. But, as autobiographical facts and semantic information share some similarities, it may be that purely semantic information can be employed to access autobiographical facts. For example, information represented in the semantic category Vehicles, such as ‘a car has wheels’ may also include autobiographical facts such as ‘my car has a stereo’. If such were the case then it should be possible to prime autobiographical fact verification by the prior presentation of a related semantic category name. The study reported below investigated this possibility. Verifying autobiographical facts There have been very few studies of autobiographical fact verification. One notable study was, however, reported by Kolers and Palef (1976). The central purpose of their study was to examine how people could rapidly and reliably assert that they did not know something. In one condition subjects were asked whether they had visited various cities. It was found that subjects were often faster at correctly asserting that they had not visited a city than correctly asserting that they had visited a city. These findings demonstrated that memory was not exhaustively searched in order to negate a query but, rather, that information became available early in the search process which facilitated correct rejection of the question.

Autobiographical

facts

43

Kolers and Palef argue that “recognition can occur as the reinstitution of the set of analytical operations that were first directed at a stimulus” (p. 557). They consider that such encoding operations have structure and that, at retrieval, this structure is accessed. The access procedure is characterised as a set of lock-and-key operations and fails when the retrieval process cannot produce a ‘key’ or find a ‘lock’. Kolers and Palef suggest that searches for what is ‘unknown’ would be rapid because the search procedure would quickly halt and return the message ‘unknown’. Glucksberg and McCloskey (1981) in a similar study found that ‘don’t know’ responses to questions concerning real world knowledge were made more quickly when no relevant facts concerning that knowledge were available in memory. They argue that question answering may be mediated by a two-stage retrieval process. In the first stage related information is retrieved from memory if, however, no related information is accessed a fast response may be executed. When related information is accessed then a second stage, that of evaluation of the retrieved information, may operate and this will act to lengthen responding. Thus both approaches emphasise that responses may be executed on the basis of the output of a memory search (fast response) or on the basis of an evaluation of retrieved information (slow response). In addition to this Kolers and Palef also found that their subjects employed various strategies in verification. One strategy was to elaborate a question such as ‘Have you been to Paris.7’ into ‘Have I ever been to France?‘. Thus, as subjects employed semantic category superordinates (country names) in the process of verification, the proposal of a close association between autobiographical and semantic facts has some tentative evidence in its favour. The present study investigated primed autobiographical and semantic fact verification. It was decided to collect from subjects overlearnt autobiographical information such as name, home town of parents, types of relatives, items of furniture in a person’s home, vehicles currently owned by a person, etc. These questions were so designed as to elicit autobiographical knowledge from subjects about items which were members of semantic categories. On the basis of this it was then possible to construct an experiment which involved the verification of true and false, autobiographical and semantic facts, half of which were primed with a semantic category name and half of which were primed with a neutral word. If (true) autobiographical facts can be indexed by semantic information then verification times should be facilitated by the prior presentation of a semantic category name. It is not clear, however, what effect priming will have on false autobiographical fact verification. Although one possibility is that verification of false autobiographical facts will be independent of priming and may, overall, be as fast as verification of true autobiographical facts

44

M.A.

Conway

(Kolers and Palef, 1976). Finally, semantic primes should facilitate verification of both true and false semantic facts. Holyoak and Glass (1975) found that one way in which subjects responded to false assertions concerning semantic category members was by generating the superordinate category name and employing this in the verification process. As superordinate category names are provided as primes in the present experiment, verification should be speeded in this condition. The superordinate categories may also activate category members and this should facilitate the verification of true semantic facts. Method Subjects Thirty-six subjects, all Cambridge undergraduates, took part in a two-phase experiment. Responses from 6 subjects on the first phase proved unsuitable and 30 subjects were selected for the next phase. Due to unavailability a further 2 subjects were omitted. The final subject sample was made up of 22 males and 6 females, giving a total of 28 subjects with a mean age 20.4 years. Design In phase one of the experiment subjects completed a two-part autobiographical memory questionnaire (described below). On the basis of subjects’ responses to the questionnaire the following fact verification experiment was constructed. A 2 x 2 x 2 x 8 within subjects design was employed. The first factor was whether the questions were True or False. The second factor was Priming, of which there were two levels, Prime and No-Prime. The third factor was question type, semantic fact or autobiographical fact. The fourth factor was the eight questions in each condition. There were 64 questions in all. Subjects were required to respond True or False to each question and the dependent variable was verification time measured in m illiseconds (ms). Stimuli selection In the first phase of the experiment subjects completed a two-part personal memory questionnaire. In the first part of the questionnaire subjects answered 27 questions designed to elicit information about overlearnt autobiographical information. These questions were also designed so that they drew on exemplars which were included in semantic categories. In the second

Autobiographical

facts

45

part of the questionnaire subjects wrote descriptions of life-time periods. The data from this latter task do not feature further in the present report. The first stage in the selection of questions from the autobiographical memory questionnaire involved identifying which of the 27 questions had been answered by the majority of the subjects. Twenty-three of the subjects had answered the same 16 questions but the remaining five subjects had only answered 14 of these questions. However, 2 other questions were identified which these five subjects had all answered. These additional two questions were substituted for the missing questions for these five subjects. Thus the question set was selected from a pool of 18 questions, which are listed with their category headings in the Appendix. In the original design of the questionnaire an attempt had been made to construct questions which, as far as possible, corresponded to categories reported by Battig and Montague (1969). In those cases where this was not possible categories were used that might reasonably be judged to be semantic. One such category was that of ‘A’ Levels. The majority of British undergraduates have at least three advanced (A) level passes in different educational subjects. The most typical combination for our subject sample was Physics, Maths, and Chemistry. Obviously there are a large number of ‘A’ level topics some of which may be more typical of the category than others. It was concluded that this category was similar to categories such as Furniture, Fruit and Sports, given a student subject population. In cases where subjects listed a number of responses to a question the first response was always used. Stimuli

construction

True autobiographical fact questions were constructed for each subject in each of the 16 categories. Although not always possible an attempt was made to include the semantic category name (the prime) in the question. However, for any subject only about 40% of the questions contained the semantic category name. These questions also varied in length between four and eight words. Corresponding true semantic fact questions were constructed by pairing the subject of the true autobiographical fact with its semantic category name. Word lengths of true semantic fact questions were matched with true autobiographical fact questions. All true semantic questions included the category name to be used as a prime. Examples of true autobiographical and semantic fact questions are listed in the Appendix.. False autobiographical fact questions were constructed by supplying a false fact about the subject of the true question. These questions varied in length between four and eight words. False semantic fact questions were constructed by pairing a typical exemplar from a category not already used in the total

46

M.A.

Conway

stimulus set with the same category of the false autobiographical fact question (see Appendix). The eventual stimulus set for each subject consisted of 16 true autobiographical facts, 16 false autobiographical facts, 16 true semantic facts, and 16 false semantic facts. For each subject, in each of the four conditions, eight facts were randomly allocated to the Prime condition and the remaining eight to the No-Prime condition. Questions were reallocated if a condition contained an imbalance of either short or long questions. Thus word length of all questions in different conditions was balanced but within conditions questions varied in length. The word ‘Ready’ was the No-Prime. Presentation of primes plus sentences was randomised for each subject. Apparatus

Stimuli were presented on Torch 280 plus BBC Acorn m icrocomputer running a programmable tachistoscope (Norris, 1984). Stimuli were presented in upper case on a black and white monitor. A two key response box was also employed. Procedure

Four to five months after completing the autobiographical memory questionnaire subjects were contacted and asked to take part in a further experiment. Subjects were unaware of the relationship between the two phases of the experiment. Subjects were seated at a table containing the monitor and response box. Subjects were given written instructions which outlined the sequence of events on any one trial of the experiment. The sequence of events were as follows: a Prime was displayed in the centre of the screen for 1000 ms followed by a blank field for 500ms, a question was then displayed, centred on the screen, until the subject responded. Response time was measured from question on-screen to key press. There then followed an inter-trial interval of 2000ms. The next trial followed automatically. Subjects were told to, “answer the question as quickly and as accurately as you can by pressing the appropriate response key”. The response keys were marked ‘Yes’ and ‘No’. Subjects held the response box in both hands with the thumb of each hand resting on the response keys. Subjects always pressed the Yes response key with their dominant hand. Key press was recorded. Subjects were also informed that each question would be preceded by a prime and that, when the prime was a word other than ‘Ready’, they should “read it silently and think about what it means”. In response to the

Autobiographical

facts

47

No-Prime subjects were told to look at the screen and prepare to answer a question. Subjects were also informed that the questions would be very easy to answer and in no case would they be unable to answer a question. After completing the verification task subjects were provided with printed lists of all questions and marked which questions were true and which were false. (Note, that very few discrepancies were observed between facts marked as true or false here and their corresponding status as true or false facts in the RT phase of the experiment. Only four subjects showed any discrepancies and these related to no more than two responses per subject. Such responses were treated as errors.) The experiment took less than 15 minutes to complete. Subjects received a small payment for their participation and were debriefed. Results The data was entered in a within subjects analysis of variance containing the following factors: true autobiographical facts, false autobiographical facts, true semantic facts, and false semantic facts formed the four levels of the factor Groups; Subjects were nested within Groups; prime and no-prime were the two levels of Primes; and the eight questions in each cell of the design comprised Items. Subjects and Items were treated as random variables (Clark, 1973) and Min F’ ratios were calculated. Errors in all conditions were less than 3% and did not vary systematically with treatment. All errors were replaced by the individual subject mean for that condition. A significant effect of Groups was observed, Min F’(3, 110) 2.8 p < .045. True facts were always verified more quickly than false facts and the overall mean RTs were: true autobiographical facts 1132ms, true semantic facts 1131ms, false autobiographical facts 1257 ms, false semantic facts 1274 ms. In general this finding does not support Kolers and Palef (1976) who found that false facts may be verified as quickly as true facts. A significant effect of Primes was found, Min F’(1, 8) 7.6 p < .025. Verification RTs to primed facts (1128ms) were reliably faster than verification RTs to unprimed facts (1269ms), indicating that the primes facilitated personal and semantic fact verification equally. No significant interaction of Groups and Primes was observed, however, prime effects were not consistent within groups and in order to examine this a-Newman-Keuls analysis was conducted (Winer, 1971, p. 80). Note that the analysis was first performed across Subjects and then, separately, across Items. Only comparisons which were significant across both Subjects and Items are reported. Table 1 lists all means in ascending order and shows which means differed significantly from each other.

48

M.A.

Table

1

Conway

Comparisons

of mean verification

times (in milliseconds)

Conditions”

Fact source Fact type

Primed Sem. True

Primed Aut. True

Primed Sem. False

No Prime Am. True

No Prime Sem. True

Mean

1038

1049

1192 ** **

1214 ** **

1234 ** **

Priming

(6)

(7)

(8)

Primed Aut. False

No Prime Aut. False

No Prime Sem. False

1270 ** ** ** **

1357 ** ** ** ** ** ** **

1244 ** ** **

(1)

(2) (3) (4) (5)

(6) (7)

‘Sem. = Semantic; Aut. = Autobiographical. Numbers in parentheses along the columns refer to the mean in that column. Numbers in parentheses on the rows refer to comparisons of all other means with the mean on that row. Columns marked ‘**’ differed significantly @ < .Ol for all comparisons) from the mean for that row. Unmarked colitmns did not differ significantly.

Verification of primed true autobiographical facts was reliably faster than verification of unprimed true autobiographical facts, (means (2) vs. (4) in Table 1). A similar reliable priming effect was found for verification of true semantic facts (means (1) vs. (5)). P rimed true personal and semantic facts did not differ in verification time (means (2) vs. (1)). Also unprimed true autobiographical and semantic facts did not differ in verification time (means (5) vs. (4)). Taken together these findings suggest that autobiographical and semantic facts may be accessed by similar information. Verification times to primed and unprimed false autobiographical facts did not differ (means (6) vs. (7)). H owever, verification times to primed and unprimed false semantic facts differed significantly (means (3) vs. (8)). Furthermore, RTs to primed false semantic facts were significantly faster than RTs to primed false autobiographical facts (means (3) vs. (6)) and RTs to unprimed false semantic facts were significantly slower than RTs to unprimed false autobiographical facts (means (7) vs. (8)). Thus, primes had little effect upon the correct rejection of false autobiographical information which was reliably slower than the correct rejection of primed false semantic facts and reliably faster than the correct rejection of unprimed false semantic facts.

Autobiographical

facts

49

These findings suggest that the rejection of false autobiographical facts may take place on the basis of information not directly associated with a semantic category but which, nevertheless, affords a more rapid judgement than rejection of unprimed false semantic facts. For example, if RTs to unprimed false semantic facts reflected a verification process which entailed generation of superordinate category names (Holyoak & Glass, 1975; Kolers & Palef, 1976), then this took more time than the verification process mediating rejection of false autobiographical facts. Finally reliable differences were observed between RTs to true and false facts; RTs to true autobiographical facts were significantly faster than RTs to false autobiographical facts (means (1) vs. (6); (2) vs. (3)) and RTs to true semantic facts were significantly faster than RTs to false semantic facts (means (4) vs. (7); (5) vs. (8)) and this was the case for both primed and unprimed verification. Thus, the verification of true facts was reliably faster than the verification of false facts in all conditions. Discussion The central findings were that access of true autobiographical knowledge was facilitated by semantic knowledge but thatcrejection of false autobiographical knowledge was unaffected by the prior presentation of related semantic information. Furthermore, time taken to respond to false information was always longer than time taken to respond to true information and this contrasts with the findings of Kolers and Palef (1976). These findings have implications for models of autobiographical memory organisation and for models of memory search. Autobiographical

memory

organisation

Semantic category superordinates were found to speed the verification of both autobiographical and semantic facts, when those facts were true. Speed ,of responding to primed autobiographical and semantic facts was virtually identical. These findings contrast sharply with those of Conway and Bekerian (in press). In that study superordinate semantic category primes did not produce faster retrieval of autobiographical memories cued by category exemplars compared to cued retrieval primed with a neutral word. Clearly, memory retrieval and fact verification may involve different processes, nevertheless, the present findings demonstrate that autobiographical fact access, unlike autobiographical memory retrieval, can be facilitated by the prior presentation of semantic information. These findings indicate that factual knowl-

50

M.A. Conway

edge concerning frequently repeated experiences (i.e., driving one’s car, using one’s bank) may be indexed by semantic knowledge structures such as semantic categories. One way in which these findings might be interpreted is in terms of a spreading activation model of memory retrieval (Anderson, 1983; Collins & Loftus, 1975). Prior presentation of a semantic category superordinate activates the corresponding concept in memory and activation spreading from that representation activates associated concepts such as category exemplars (Loftus, 1975). If autobiographical facts are conjointly represented with, or indexed by, category exemplars then these will also be activated and hence the facilitatory effects of the prime upon both autobiographical and semantic fact verification. This explanation, however, only applies to the verification of true facts and RTs to false facts indicated that verification of negatives may have been mediated by strategic processes acting in addition to memory search. As autobiographical facts (or at least the majority of facts employed in this study) must be abstracted from many experiences one of the features of the abstraction process would be to decontextualise the factual information. However, the abstraction process must maintain the self-reference of the information otherwise it would no longer be an autobiographical fact (Brewer, 1986). One way in which this might be achieved would be to add information to already existing context-free representations. For example, information stating that a person owns a car, perhaps what type of car, and pointers to associated autobiographical memories might be added to semantic knowledge of cars. This interpretation contrasts with previous proposals concerning autobiographical memory organisation. Kolodner (1983) argued that autobiographical memories may be represented in a network and connected by DIRECTED links. Directed links are represented by pointers between events and pointers index events according to event properties. Salient properties of events which make effective pointers depend upon the context in which an event takes place. For example, a salient feature of a meeting between two statesmen may specify the purpose of the meeting, for example, arms control, whereas the type of clothing worn by the participants, for example, suits, would be less distinctive (cf. Kolodner, 1983, p. 254). Such a model may capture important aspects of ways in which autobiographical MEMORIES are represented and accessed but it is difficult to see how this model could account for the organisation of factual autobiographical knowledge. Autobiographical facts are related to many events and thus event related information is unlikely to provide distinctive indices for factual information. Intuitively it seems unlikely that prior information such as ‘International

Autobiographical facts

51

arms control meeting’ would prime a response to the query ‘Do you own a suit?‘. The same argument applies to other models of autobiographical memory which focus on events and contexts (i.e., Conway & Bekerian, in press; Reiser et al., 198.5). Autobiographical facts may, then, be more directly indexed by other less contextually dependent factual knowledge. These findings also lend some support to current versions of the episodicsemantic distinction (Tulving, 1984, 1985). Recently Tulving (1985) has argued that there may be some embeddings between episodic and semantic memories. Clearly, semantic memory must be involved in the encoding of events and, presumably, in the abstraction of indices employed to access memories of specific events. The present findings suggest that, in addition to this, factual knowledge relating to one’s own life may be closely associated with semantic information. Perhaps then, there are two principle ways in which episodic and semantic knowledge are embedded. One embedding may be in terms of the indices (event features) of memories of specific events. Presumably, such indices form part of semantic knowledge (i.e., as an ‘abstracted’ personal history, see Conway & Bekerian, in press) but, of course, these indices must be idiosyncratic with respect to the memories they index. In addition to this autobiographical factual knowledge may represent a second way in which semantic and episodic memories are embedded and such factual self-related knowledge may be represented along with, or indexed by, purely semantic knowledge. Thus, autobiographical facts may represent one of the more direct embeddings of personal and semantic knowledge. Autobiographical

facts and knowing not

In direct contrast to Kolers and Palef (1976) the present study failed to find equally fast responses to true and false facts and true facts were always responded to more quickly than false facts. Moreover, it was also found that primes speeded verification of false semantic facts but not verification of false autobiographical facts. One reason for these findings may relate to differences between the two experiments. In the autobiographical memory component of the Kolers & Palef study subjects judged whether they had visited various cities. Times taken to make negative responses to stimuli such as ‘Paris’ were, in many cases, faster than times taken to make positive responses to stimuli such as ‘Washington’. But one problem with this procedure is that the frequency of personal experiences, relating to a target city, is not known. If autobiographical facts contain context-free information and are indexed by semantic knowledge structures then comparatively fast verification times might be expected. If, on the other

52

M.A. Conway

hand, autobiographical factual information is contained within an autobiographical memory then slower verification times might be expected. This is because a memory must be accessed and information retrieved from the trace. Time taken to retrieve a memory is, typically, about 3 seconds (Conway & Bekerian, in press; Reiser et al., 1985) whereas time taken to verify a fact is, typically, about 1 second (Holyoak & Glass, 1975). In the present study autobiographical facts referred to objects which, in general, would have been frequently experienced. Thus, it seems reasonable to assume that such information would be represented independently of specific memories and, as a consequence, could be retrieved with comparative speed. In contrast, verifying that one had visited a city, when that city had in fact only been visited once, may have required the retrieval of a specific memory and hence a long response latency. In this way judgements of true facts may vary in verification times. Factual statements which entail the retrieval of a specific memory may give rise to slow verification times in comparison to factual statements which only entail retrieval of context-free information. Faster latencies to false facts may reflect the early termination of the memory search as Kolers and Palef suggested. As these differences were not evident in the present study it may be that in this case autobiographical fact verification did not entail autobiographical memory retrieval. There was also a reliable difference between verification times to false and true autobiographical facts: times taken to affirm negation of the question ‘Do you own a car?’ were slower than times taken to positively respond to the question ‘Do you play squash?’ and this was the case for both primed and unprimed presentations. However, false autobiographical facts were created by pairing a similar item with a true item and a subject who in fact owned only a bicycle would be asked if s/he owned a car. Kolers and Palef point out that verifying false autobiographical facts concerning cities in countries one has visited takes longer than verifying similar facts concerning countries one has not visited (cf. Glucksberg & McCloskey, 1981). Kolers and Palef speculate that a false statement such as ‘Have you visited Paris’ can be quickly negated by recalling that one has never visited Europe. This superordinate strategy cannot be employed when verifying that one has never visited Manchester when one has visited other English cities. Stimuli in the present study were similar to this latter type. A subject may not have owned a car but s/he did own a vehicle of some description or a subject may not have played football but did regularly play another sport and this was the case for all the stimuli. Thus, RTs to false autobiographical facts may have been reliably longer than RTs to true autobiographical facts because all potential affirmations to the false question had to be eliminated prior to executing a negative response

Autobiographical

facts

53

whereas retrieval of a single item which matched a true question led to rapid responding. Furthermore, superordinates in the form of primes may have facilitated true responses by some process of spreading activation, as argued earlier, but a negative response would require the elimination of ALL potential true responses activated by the prime. Presumably, not all facts would have received equal activation and this may have further lengthened the process of rejection, for even weakly activated targets would have had to be eliminated from the search set prior to response. This line of argument suggests that the time taken to reject a false assertion will, in part, be determined by the extent of a subject’s knowledge of information related to the assertion (as Glucksberg & McCloskey, 1982 proposed). This constraint may, however, only restrict responding in a general sense. If virtually nothing is known about a topic then, as Kolers and Palef proposed, processing can quickly return a verdict of ‘unknown’ without an exhaustive search and this is because processing either cannot be initiated or rapidly fails. If some information related to a false fact is available, as was the case in the present study, then this information must be accessed and evaluated (Glucksberg & McCloskey, 1981) prior to correct responding. Moreover, different types of retrieved information will, presumably, differentially speed or slow a response. The above argument suggests an explanation for the differences between verification times to false personal and semantic facts. It will be recalled that semantic category superordinates primed negation of false semantic facts but not negation of false autobiographical facts. Moreover, negation of primed false semantic facts was reliably faster than negation of primed false autobiographical facts. This latter difference may have been the product of additional processing undertaken in response to these stimuli. Although it was the case that false personal facts were indeed false it was not clear whether these facts were ABSOLUTELY false. For example, a subject who did not frequently play squash would respond ‘no’ to the question ‘Do you frequently play squash?‘. That subject may, however, have infrequently played squash. Similarly a subject who responded negatively to the question ‘Do you own a car?’ may, nevertheless, have owned a car at some point in the past. Possibly, then, some additional processing of personal information indirectly related to the false questions was undertaken. This additional processing may have weakened any processing advantages conferred by the activation effect of prime. Prime effects upon the verification of false semantic facts may have been mediated by some form of heuristic such as the generation of counter-examples (Holyoak & Glass, 1975). For instance, in response to the question ‘Is an orange a vehicle?’ a subject may have retrieved the counter-example ‘An

54

M.A.

Conway

orange is a fruit’ and inferred that vehicles are not fruit. When primed with Fruit this process would have been speeded because of the prior activation of the counter-example. When the question was ‘Are oranges your favourite fruit?’ the superordinate counter-example strategy would be irrelevant. However, assuming that the prime did in fact activate a subject’s favourite fruits (all subjects’ autobiographical facts were comprised of typical category exemplars) then a counter-example to the false question should have been quickly available although not as quickly as a semantic counter-example which was available in the prime. This may account for the difference between primed false semantic and autobiographical fact verification. Finally, verification of unprimed false autobiographical facts was signjficantly faster than verification of unprimed false semantic facts. Holyoak and Glass (1975) f ound that subjects employed a number of strategies in order to reject false semantic facts, such as generation of counter-examples and contradictions. (i.e., a car cannot be eaten therefore it is not a fruit). The findings indicate that in the absence of a prime these strategies appear to be comparatively slow acting. In contrast, faster responding to unprimed false autobiographical facts may, in this case, have risen because such strategies did NOT mediate verification. False autobiographical facts may have been verified by some process which looked for records of self-reference (Keenan & Baillet, 1980). For example, once semantic information associated with the autobiographical fact had been accessed the failure to find any pointers to autobiographical memories and self-relevant information may have led directly to a fast ‘No’ response without any additional computation. Although the memory search may have been somewhat longer in this case given that other, related, autobiographical knowledge may also have been activated. In general, then, false autobiographical facts take longer to verify than true autobiographical facts. But this may only be the case when other autobiographical information relating to the false assertion is already present in memory. When related information is not present verification may be faster because processing cannot commence (Kolers and Palef, 1976). Verification of false autobiographical facts may be faster than the verification of false semantic facts because the search process quickly fails to find any record of self-reference for the false autobiographical assertion. Verification of false semantic facts requires additional computation. These findings extend the proposals of Kolers and Palef, however, other aspects of the findings question the assertion that autobiographical facts are closely associated with encoding conditions. Both Kolers and Palef. (1976) and Schank (1982) argue that autobiographical information is encoded in terms of the operations or activities undertaken at encoding and this may, indeed, be the case for memories of specific events.

Autobiographical facts

55

For autobiographical knowledge drawn from many different episodes, however, some recoding must take place and recoded autobiographical information may be represented independently of specific autobiographical memories (encoding contexts). Hence, the prime effects of semantic category superordinates upon true autobiographical fact verification in the present study. Thus, the findings indicate that autobiographical facts relating to frequently repeated experiences are closely associated with corresponding semantic information. Semantic information such as semantic categories may index autobiographical facts and this contrasts with models of autobiographical information which only emphasise event memory and single out distinctive event features as the primary form of indexing. Clearly, models of autobiographical memory which do not encompass factual personal knowledge are incomplete. The findings of this study suggest that more complete models of autobiographical memory must take into account possible embeddings between autobiographical and other types of knowledge.

Appendix Semantic categories and personal fact questions Occupations Sports Clothes Fruits Furniture Vehicles Banks Schools Names ‘A’ Levels Relatives Colleges Foods Diseases T.V. programmes

What is your father’s occupation? List up to three sports which you play frequently. What is the colour of the coat you wear most frequently? What is your favourite fruit? Do you have a desk in your room? Do you own a bicycle? What is the name of your bank? What was the name of the school you attended at the age of nine? What is your name? List three of your ‘A’ levels Do you have a sister(s) and or brother(s)? If so please list their names. If not then please give the name of a close relative about your own age. Which college are you in? List your three favourite foods. Have you had chicken pox? Have you had measles? What is your favourite television programme?

56

M.A. Conway

Toys Films Towns

What was the toy you played with most frequently as a child? What is your favourite film? In which town do your parents live?

Examples of true and false autobiographical and semantic facts True autobiographical facts Prime: FRUITS Prime: SPORTS Prime: BANKS

Question: Are apples your favourite fruit? Question: Do you often play football? Question: Do you bank with Lloyds?

True semantic facts Prime: FRUITS Prime: SPORTS Prime: BANKS

Question: Is an orange a fruit? Question: Is rugby a sport? Question: Is National Westminster a bank?

False autobiographical facts Prime: FRUITS Prime: SPORTS Prime: BANKS

Question: Are pears your favourite fruit? Question: Do you often play cricket? Question: Do you bank with Barclays?

False semantic facts Prime: FRUITS Prime: SPORTS Prime: BANKS

Question: Is an express train a fruit? Question: Is teaching a sport? Question: Is the South Pacific a bank?

References Anderson, J.R. (1983). The architecture of cognition. Hillsdale, NJ: Erlbaum. Battig, W.F., 81 Montague, W.E. (1969). Category norms for verbal items in 56 categories. A replication and extension of the Connecticut category norms. Journal of Experimental Psychology Monograph, 80 (3, pt. 2). Brewer, W.F. (1986). What is autobiographical memory? In D.C. Rubin (Ed.), Autobiographical memory. London: Cambridge University Press. Clark, H.H. (1973). The Language-as-fixed-effect fallacy; A critique of language statistics in psychological research. Journal of Verbal Learning and Verbal Behaviour, 12, 335-359.

Autobiographical

Collins, A.M., Review,

facts

57

& Loftus, E.F. (1975). A spreading activation theory of semantic processing. Psychological 82, 407-428.

Conway, M.A., & Bekerian, D.A. (in press). Organization in autobiographical memory. Memory and Cognition.

Crovitz, II., & Schiffman, H. (1974). Frequency of episodic memories as a function of their age. Bulletin of the Psychonomic Society, 4, 517-518. Glucksberg, S., & McCloskey, M. (1981). Decisions about ignorance: knowing that you don’t know. Journal of Experimental Psychology: Human Learning and Memory, 7, 311-32.5. Holyoak, K.J., & Glass, A.L. (1975). The role of contradictions and counterexamples in the rejection of false sentences. Journal of Verbal Learning and Verbal Behaviour, 14, 215-239. Keenan, J.M., & Baillet, S.D. (1980). Memory for personally and socially significant events. In R.S. Nickerson (Ed.), Attention and Performance VIII (p. 651-669). Hillsdale, NJ: Erlbaum. Kolers, P.A., & Palef, S.R. (1976). Knowing not. Memory & Cognition, 4, 553-558. Kolodner, J.L. (1983). Maintaining organization in a dynamic long-term memory. Cognitive Science, 7, 243280. Linton, M. (1982). Transformations of memory in everyday life. In U. Neisser (Ed.), Memory observed. Oxford: W.H. Freeman. Loftus, E.F. (1975). Spreading activation within semantic categories: comments on Rosch’s “Cognitive representation of semantic categories”. Journal of Experimental Psychology: General, 104, 234-240. Norris, D. (1984). A computer based tachistoscope for nonprogrammers. Behavioral Research Methods, Instrumentation,

and Computers,

16, 23-27.

Reiser, B.J., Black, J.B. & Abelson, R.P. (1985). Knowledge structures in the organization and retrieval of autobiographical memories. Cognitive Psychology, 17, 89-137. Robinson, J.A. (1976). Sampling autobiographical memory. Cognitive Psychology, 8, 578-595. Rubin, D.C., (1982). On the retention function for autobiographical memory. Journal of Verbal Learning and Verbal Behaviour, 21, 21-38. Rubin, D.C., & Kozin, M. (1984). Vivid memories. Cognition, 16(l), 81-96. Schank, R.C. (1982). Dynamic memory: A theory of reminding and learning in computers and people. New York: Cambridge University Press. Tulving, E. (1984). Precis of elements of episodic memory: Author’s response. The Behavioural and Brain Sciences, 7(2), 257-263. Tulving, E. (1985). How many memory systems are there? American Psychologist, 40, (4), 385-398. Winer, B. (1971). Statistical principles in experimental design. New York: McGraw-Hill

L’Ctude de la memoire auto-biographique s’interesse exclusivement aux souvenirs d’experiences specifiques. Les modeles actuels (Kolodner, 1983) postulent pour les souvenirs auto-biographiques une representation en reseau, oti des traits distinctifs d’evenements servent d’indices permettant d’acceder a des souvenirs associes. Mais le savoir auto-biographique (comme la connaissance de notre nom), qui provient d’experiences variees et frequemment rep&es, peut avoir une representation dans la memoire independante de tout souvenir specifique, et n’est done probablement pas index6 par de l’information sur des Cvenements. 11est possible que les faits auto-biographiques soient represent& comme d’autres types de connaissances factuelles (par exemple, les connaissances semantiques). Afin d’etudier cette possibilite, nous avons realist une experience de verification de faits dans laquelle les sujets devaient verifier des faits semantiques et auto-biographiques vrais ou faux apres presentation d’un nom de categoric semantique ou d’un mot neutre. La verification de faits auto-biographiques et stmantiques vrais Ctait plus rapide lorsqu’elle suivait la presentation d’un nom de categoric, ce qui demontre que I’information auto-biographique peut &tre indexte par de I’information semantique. La verification de don&es autobiographiques fausses Ctait plus rapide que la verification de donnees semantiques fausses, ce qui suggere que l’absence d’auto-reference des premieres permettait une reponse rapide. D’autres

58

M.A. Conway

resultats ont montre que la vitesse de verification des donnees auto-biographiques depend peut-&tre en partie de ia quantite d’informations associees dejri presentes darts la memoire. Ces resultats montrent que tomes les informat~ons auto-biographiques ne peuvent pas &tre representees conjointement avec les souvenirs d’exptriences specifiques ni indexees par de I’information associee a des Cvenemcnts. Notre conclusion est que les mod&s actuels de la memoire auto-biographique doivent tenir compte des relations entre l’information auto-biographique factuelle et d’autres types d’information factuelle.