THREE PROCESSES INVOLVED IN MEMORY CREATION

Three processes are involved in the creation of false childhood memories:

plausibility judgments, image and narrative construction, and source monitor- ing judgments (Hyman & Kleinknecht, 1999). First, an individual judges

the plausibility of a the suggested event: Is the event something that the person believes could have happened to them? For example, some partici- pants in the research by Hyman and his colleagues (Hyman & Billings, 1998; Hyman et al., 1995; Hyman & Pentland, 1996) did not create memo- ries of spilling a punch bowl at a wedding because they believed that they had never attended a wedding as child. They refused to accept the event as a plausible personal experience. Plausibility is a judgment that people make based on various types of information.

Various factors influence plausibility judgments, including: the source of a suggestion, an individual’s belief about the general frequency of the event, whether the individual has experienced similar events, the connec- tions made between the event and various aspects of the individual’s cur- rent state, the ease with which the event comes to mind. In addition, there are several methods for suggesting to an individual that an event is gener- ally, and individually, plausible. Event plausibility can be stated directly (25% of adults were sexually abused), tied to a particular characteristic that an individual may possess (the majority of people with that problem were abused as children), tied to an individual’s personality (many people like you were abused), or implied by social groupings (you are like the people in this group and they were all abused).

Once someone believes that an event is personally plausible, that per- son still must construct a memory: an image with a narrative. People can believe, or even know, that an event occurred, without having a memory of the event. Since Bartlett (1932), researchers have studied memory con- struction. Memory is not like videotape—people do not simply retrieve a memory and replay the experience. Instead, people construct a memory by combining schematic knowledge from various sources with personal experiences, suggestions, and current demands. All memories are con- structions.

Even when people believe an event is plausible and construct an image of the event, they still may not think that their knowledge is a personal memory. For example, all of the participants in the imagery condition of Hyman and Pentland’s (1996) study constructed an image of spilling the punch bowl at a wedding and described that image in a narrative. Many, however, did not claim the image as a memory; instead, they correctly at- tributed the source of the image to a creation in response to the sugges- tion. In contrast, others made a source monitoring error: They claimed the constructed images as a personal memory. This illustrates the final proc- ess involved in creating a false memory. In addition to accepting an event as plausible and constructing a memory, people must make a source mon- itoring error—they must claim the false memory as a personal memory. Many studies have shown that people experience difficulties remember- ing the source of information they have learned (see Johnson, Hastroudi, & Lindsay, 1993). In addition, source misattributions have been suggested as a primary cause of the misinformation effect—people remember the misleading postevent information and incorrectly attributed the informa- tion to the original event (e.g., Zaragoza & Lane, 1994).

Although the processes of plausibility judgment, memory construction, and source monitoring error may occur in a linear fashion and be depend- ent on the preceding step, we suspect that the processes are somewhat in- teractive. For example, producing a clear image may influence one’s as- sessment of the plausibility of an event having occurred (Garry, Manning, Loftus, & Sherman, 1996). It may be more accurate to claim that all three processes are necessary for false memory creation but that the processes are somewhat independent because different situational factors and indi- vidual differences may influence each process. False memory research can be interpreted in terms of this general framework of plausibility judg- ments, image and narrative construction, and source monitoring errors. We use the framework to integrate many of these findings and provide in- formation about how people make plausibility judgments and how source monitoring errors occur in autobiographical memories.

Plausibility Judgments

In order for someone to create a false memory, that person must first ac- cept the suggested event as plausible. Pezdek et al. (1997) documented the role of the event in plausibility judgments. They suspected that events that were similar to scripts from an individual’s childhood would more likely be adopted as personal memories. In their first experiment, the research- ers suggested false events that either did or did not match the religious background of their participants. The participants were either Catholic or Jewish. Thus, the false events were variations of Shabbat dinners and

Communion services. In agreement with their predictions, they found that individuals were more likely to create memories for events that matched their religious background than for events that did not (i.e., for a Catholic, the event involving Communion as opposed to the event involv- ing Shabbat). In a second experiment, Pezdek and colleagues suggested a plausible event (being lost in a mall) and a less plausible event (receiving an enema). They argued that people have script knowledge of being lost that makes the event more easily accepted and created. They found that people have a greater tendency to create a memory of being lost than a memory of receiving an enema. In both cases, Pezdek et al. argued that plausible events are more likely to result in false memories.

Plausibility is not, however, simply a matter of the event. Plausibility judgments also depend on whether the event matches an individual’s ex- pectancy for a class of experiences. People rate the likelihood of events dif- ferently. For instance, most people think abduction by extraterrestrials is unlikely. Others may consider such an event relatively common. For ex- ample, Spanos, Cross, Dickson, and DuBreuil (1993) looked for personal- ity factors to explain the difference between people who claimed to have had encounters with UFOs and individuals who did not claim such expe- riences. They found that belief in alien visitations was the primary vari- able that differentiated people who claimed such memories from individ- uals who did not. Knowledge and beliefs about the frequency of an event influence plausibility judgments. Knowledge and beliefs about the fre- quency of childhood abuse can influence individuals’ judgments of how plausible an abuse experience is for them. In today’s society sexual abuse is widely discussed and suggestions are made that many people have ex- perienced child abuse.

Not only will people judge plausibility based on personal experiences and beliefs about the general frequency of events, but it is also possible to manipulate people’s plausibility judgments. Kelley, Amodio, and Lindsay (1996) provided people with false feedback as a means of manipulating plausibility judgments and creating false memories. They gave partici- pants a series of tests that were supposedly designed to assess innate handedness: whether someone was truly right- or left-handed. All partici- pants were right-handed, and the tests were not actually constructed to provide information on native handedness. Nonetheless, Kelley et al. told some individuals that, based on the test results, they most likely were born left-handed. Other individuals were told that their test results indi- cated that they were right-handed. People believed this feedback even though the researchers told the participants that the tests were only pre- liminary. Kelly et al. suggested that the people try to remember times when they had been shaped to use their right hand rather than their left hand. A few days later, individuals who were given the false feedback

that they were born left-handed remembered many more instances of hand-use shaping than those who were told that they were right-handed. Loftus (1997) reported a similar investigation in which she and her col- leagues suggested to individuals that, based on test results of their visual abilities, the hospital most likely had hung colorful mobiles over their cribs when they were newborns. After time, many individuals claimed to remember seeing such a mobile over their crib—a memory that cannot be true given memory and visual development.

Similarly, Hyman, Chesley, and Thoelke (1997) used a Barnum-type methodology to provide false feedback and manipulate plausibility judg- ments of childhood experiences. The goal was to provide reasons for peo- ple to believe that certain events were likely to have occurred to them. Hyman et al. accomplished this by connecting rare childhood events to bogus personality feedback. In classic investigations of the Barnum effect, individuals took a personality test and were provided feedback suppos- edly based on the test. The feedback was not, however, based on the per- sonality test. Instead, all participants received identical feedback contain- ing statements that were vague and generally socially desirable and positive. The typical finding was that most individuals rated the resulting personality description as describing them.

Hyman et al.’s research on plausibility judgments began as a Barnum- type study. They administered two personality tests in a large introduc- tory psychology class. The students were told that the researchers were in- vestigating the relation between personality and autobiographical mem- ory. One week later all students were provided with a packet containing their “individual” feedback and a followup questionnaire on autobio- graphical memory. The individualized feedback was bogus—all students were provided with the same personality description. The students were asked to read their personality description and rate how well it described them. After the students rated the personality description, they were asked to respond to the autobiographical memory questionnaire: This was the extension they added to the standard Barnum methodology. All stu- dents were told that the autobiographical memory questionnaire included some events that were likely to have happened to them, and other events that were unlikely to have happened to them based on their personality type. The students rated each event on a 7-point scale ranging from 1 (did

not happen) to 7 (did happen).

Generally, the students rated the personality description as a good fit. Although there was an overall tendency for individuals to rate the events the researchers told them were likely as more plausible than the events they stated were unlikely, the effect was more profound for individuals who accepted the personality description. Individuals who rated the de- scription as a better characterization of themselves rated the events they

were told were more likely to have occurred as more plausible. Those in- dividuals who accepted the self-description also rated as more plausible the events that were tied to that self-description. In the Kelley et al. (1996) and Hyman et al. (1997) studies, event plausibility judgments were ma- nipulated by connecting childhood events to false personality feedback. Thus, plausibility judgments are assumed to be based on personal script knowledge of the event, general beliefs about the frequency of events, and connections of the suggested events to an individual’s personality charac- teristics, whether the personality feedback is true or false.

In an extensive series of studies, Loftus and her colleagues investigated other methods of affecting plausibility judgments. Previously, researchers have shown that imagining a possible future event can increase a person’s judgment of the likelihood that the event will occur (Carroll, 1978; Greg- ory, Cialdini, & Carpenter, 1982; Sherman, Cialdini, Schwartzman, & Reynolds, 1985). Imagining the event makes it come to mind with greater fluency in subsequent tasks. In many judgments, the ease with which an event comes to mind determines the judgment (Jacoby, Woloshyn, & Kelley, 1989; Tversky & Kahneman, 1973). Subsequently, Garry, Manning, Loftus, and Sherman (1996) wondered if imagining an event would have the same effect on plausibility judgments for past events.

Garry et al. (1996) used the Life Events Inventory (LEI) to rate whether or not a series of childhood events had happened to a group of college stu- dents. The participants were asked to rate each event using a Likert scale ranging from 1 (definitely did not happen) to 8 (definitely did happen). This rat- ing is a reflection of many possible sources of knowledge. A person can rate the event as definitely having occurred if they remember it, if they know about the event from other sources but do not remember it, or if they have some other reason for believing the event occurred. In a sepa- rate experimental session, participants were asked to imagine possible childhood events including events presented on the LEI. Participants were asked to complete the LEI again. The results demonstrated how im- aging affected ratings for events that participants previously rated as likely did not happen (a rating of 4 and below on the 8-point scale).

It was hypothesized that when participants imagined childhood events that they had previously rated as unlikely, the act of imagining would in- crease fluency for the events. Therefore, when the events were considered while completing the LEI, the events would come to mind more easily. This fluency would prompt people to inflate their ratings of the possibility that the event occurred. Garry et al. (1996) observed that individuals who imagined unlikely events were more likely to increase their ratings for those events than those who did not imagine the previously unlikely events. Imagining an event can affect fluency and increase plausibility judgments.

Using this method, Loftus and her colleagues explored a variety of manipulations that affect plausibility judgments, and in some cases con- tribute to the creation of childhood memories. For example, Pickrell and Loftus (1999) investigated if plausibility judgments are affected by partici- pants reading examples of an experience. If estimates of plausibility, or ratings of whether participants think the event happened to them, are based on the ease with which the event comes to mind, then any addi- tional recent experience with the event should inflate plausibility ratings. Pickrell and Loftus found that individuals who read examples of child- hood events rated the events as more likely to have occurred than did in- dividuals who did not read event examples.

Mazzoni and Loftus (Mazzoni & Loftus, 1998; Mazzoni, Loftus, Seitz, & Lynn, 1999) studied the effects of dream interpretation on event plausibil- ity ratings. First, participants completed a LEI. Next, the individuals par- ticipated in an apparently separate experiment involving dream interpre- tation. Regardless of the dream scenario that the individuals reported as part of the experiment, they were told that the dream indicated a critical childhood experience (such as being lost or being harassed by a bully). Later, the participants filled out another LEI, which included a critical item of being lost or harassed by a bully. Again, plausibility ratings on the LEI were inflated—the participants’ belief that the experience had hap- pened to them increased after the dream interpretation session. In addi- tion, the researchers asked the participants to report any particular memo- ries that they had of the disclosed experiences. Nearly half of the participants who experienced the dream interpretation reported actual ex- periences in agreement with the suggested experience. The dream inter- pretation not only affected plausibility estimates, but also resulted in com- plete memory creation for some individuals.

As Pezdek et al. (1997) argued, plausibility is a crucial factor in the cre- ation of false childhood memories. Pezdek et al. argued for a narrow defi- nition of plausibility related to an individual’s script knowledge for an event based on personal experience. In contrast, Hyman and Kleinknecht (1999) argued that plausibility is a judgment that people make based on a variety of information. Therefore, plausibility judgments are affected by beliefs about event likelihood (Spanos et al., 1993), by making connections to an individual’s understanding of self (Kelley et al., 1996; Hyman et al., 1997), by the availability of the event, which is influenced by imagining and reading about the event (Garry et al., 1996; Pickrell & Loftus, 1999), and by dream interpretation (Mazzoni et al., 1999). Undoubtedly, other factors also influence how people make judgments about event plausibility.

By themselves, manipulations of plausibility judgments may lead to the creation of false memories (e.g., Mazzoni et al., 1999). Often, however, people can accept that an event is plausible, that it is likely to have hap-

pened to them, without actually remembering the event. The second step in the creation of memories is the construction of a memory—an image with a narrative. Once individuals create an image and narrative, they still must make an additional judgment error—they must claim the constructed memory as a personal memory. In the next section we focus on research re- lated to source monitoring errors in autobiographical memories.

Source Monitoring Errors

People make a variety of source monitoring decisions about the contents of their memory. Some decisions focus on discriminating among external sources of information: trying to remember who told you a joke, whether you learned a piece of news from the newspaper or from television, or try- ing to remember what class covered which topic. Other source monitoring decisions focus on discriminating between internal and external sources of thoughts and images: Was that something I did or did I only imagine it, dream it, or plan to do it? Discriminating the source of an image and nar- rative created in response to a suggestion can be difficult. A person must decide if the event is a personal memory. Internal and external sources are not mutually exclusive: The individual may continue to recall hearing about the event from the interviewer, but may also decide that the event is also remembered.

Johnson and her colleagues (Johnson, Foley, Suengas, & Raye, 1988; Johnson, Hastroudi, & Lindsay, 1993) have argued that source decisions are made based on the qualities of a memory. When memories are clear and contain an abundance of sensory information, the implication is that the sensory information could only be due to recollections of the original experience. People often claim that such a memory is a personal recollec- tion. In contrast, if the contents of a memory are vague, include minimal sensory information, and contain a lot of information based on thought processes and reasoning, then people frequently decide that the experi- ence is not a remembered event.

In an attempt to investigate how people make source monitoring deci- sions, Johnson et al. (1988) asked participants to remember a childhood experience and imagine a childhood experience. The participants rated both their memory and their image according to scaled questions. Several questions focused on the sensory qualities of the memory. Johnson et al. found that participants rated remembered events as more clear on the sen- sory characteristics questions than events that they imagined. The results indicated that people rely on phenomenological memory characteristics to decide if they remember something or if they only imagined it. The deci- sion process is only reliable to the extent that the sensory characteristics are the result of directly experiencing an event. If the sensory characteris-

tics can be introduced by other means, then the decision process can lead to erroneous source monitoring decisions.

Based on Johnson’s source monitoring theory (Johnson et al., 1988; Johnson et al., 1993), Hyman, Gilstrap, Decker, and Wilkinson (1998) investigated how people make source judgments about autobiographical knowledge. The researchers relied on the remember–know distinction sug-