Can a witness report hearsay evidence unintentionally

When eyewitnesses are exposed to misinformation about an event from a co-witness, they often incorporate this misinformation in their recall of the event. The current research aimed to investigate whether this memory conformity phenomenon is due to change in the witness‟s memory for the event, or to social pressures to conform to the co-witness‟s account. Participants were shown a crime video and then asked to discuss the video in groups, with some receiving misinformation about the event from their discussion partners. After a one week delay some participants were warned about possible misinformation before all participants provided their own account of the event. In Study 1, participants made remember/know judgments about the items recalled, and in Study 2 they indicated the source of their memories. Co-witness information was incorporated into participants‟ testimonies, and this effect was not reduced by warnings or source monitoring instructions, suggesting memory change may have occurred. However, there was some indication that remember/know judgments may help distinguish between „real‟ memories and co-witness information. Discussion and Eyewitness Memory 3 Can a witness report hearsay evidence unintentionally? The effects of discussion on eyewitness memory Within the legal system it is commonly held that the most reliable eyewitness evidence is that given by independent eyewitnesses who have not communicated with one another (e.g., Heaton-Armstong, 1987). Consequently, many legal procedures are designed to prevent eyewitnesses from discussing the crime with one another. For example, a survey of police officers has revealed that they often attempt to separate witnesses and discourage them from talking about the event with one another (Paterson & Kemp, 2005). Despite these attempts, it is clear that witnesses often do talk to each other about the event they saw. Recent studies have found that the majority of eyewitnesses reported discussing details of the event with their co-witness (Paterson & Kemp, 2006a; Skagerberg & Wright, 2008). Discussion between witnesses is problematic because research has shown that exposure to co-witness information about an event after it has occurred often causes people to incorporate this information into their accounts of the event. In fact, research has shown that co-witness information presented in this way is a more influential method of presenting misinformation than leading questions or written postevent narratives (Paterson & Kemp, 2006b). Similarly, another study has shown that postevent information encountered through co-witness discussion was significantly more influential than that encountered through a non-social source (Gabbert, Memon, Allan, & Wright, 2004). This phenomenon has become known as „memory conformity‟ (e.g., Gabbert, Memon, & Allan, 2003; Wright, Self, & Justice, 2000). Research has shown that participants who have discussed an event with a cowitness who supplies misinformation show less accurate memory for the misled items than non-misled items (e.g., Hoffman, Granhag, See & Loftus, 2001; Schneider & Discussion and Eyewitness Memory 4 Watkins, 1996; Shaw, Garven, & Wood, 1997) and their memory is also less accurate for misled items than individuals who did not discuss the event (e.g., Gabbert, Memon, Allan, & Wright, 2004; Hollin & Clifford, 1983). Despite this clear evidence of co-witness memory conformity, we do not know why witnesses often report information provided by a co-witness. Some researchers have attempted to address this issue (e.g., Azad, Lindsay& Brimacombe, 2010; Gabbert et al., 2007; Paterson & Kemp, 2006), however it remains unclear whether the conformity is due to memory distortion or other factors. Memory conformity could occur without any memory distortion if the participant reports co-witness information for other, more social, reasons. For example, an individual may conform in order to gain social approval (normative social influence), or they may report the second-hand information because they believe it to be correct (informational influence; Deutsch & Gerard, 1955). These mechanisms require that witnesses remember the co-witness information and that it was obtained from a second-hand source. For this reason, Betz, Skowronski, and Ostrom (1996) refer to these mechanisms as “source-tagged mechanisms.” An alternative explanation for memory conformity suggests that memory change does occur. For example, according to the source monitoring theory (e.g., Johnson, Hashtroudi, & Lindsay, 1993; Lindsay & Johnson, 1989), a witness may remember the information provided by the co-witness, but forget that it was obtained secondhand. Thus, source-monitoring theory suggests that people report co-witness misinformation because they misremember the source of information they recall. The investigation as to why participants often report co-witness information has important legal implications. If witnesses are unable to distinguish what they actually experienced from information obtained from a co-witness, then they may, in Discussion and Eyewitness Memory 5 effect, be reporting hearsay evidence without knowing it. The legal concept of „hearsay‟ embodies the notion that “a witness‟s assertions of relevant facts should be based upon his or her own experiences” (Forbes, 2003, p. 59) and not those of another. However, implicit in this concept is the assumption that witnesses are able to distinguish their own experiences from information they obtain second-hand (e.g., from a co-witness). That is, within the legal system there is an assumption that witnesses would only report hearsay evidence because of social influence and not because of memory change, but this may not be the case. If witnesses are unable to distinguish their „real‟ memories from second-hand information then their testimonies are considered „contaminated‟ and this may lead to the unintentional presentation of hearsay evidence. Researchers have employed three techniques in an attempt to identify the mechanism responsible for memory conformity. The first method has been to ask participants to make a remember/know judgment (Tulving, 1985) for each item they recall following the discussion. Roediger, Meade and Bergman (2001) had participants recall items from images of common household scenes in alternation with a confederate who sometimes recalled items that were not in the scenes. Participants were asked to produce a remember/know judgment for each item they recalled. If they consciously remembered seeing the object in the scene they would indicate that they “remembered” it. In contrast, “know” responses were used to indicate items for which the participants did not have any specific recollection, but which they believed to be in the scene. When participants incorrectly reported items mentioned by the cowitness, they were more likely to claim that they “knew” the suggested items had been in the scenes than to report that they specifically “remembered” seeing them there. These results were replicated in studies by Meade and Roediger (2002). This Discussion and Eyewitness Memory 6 implies that participants are at least partially able to discriminate between information obtained from a co-witness and that obtained first-hand from the scene. The second experimental technique used to determine the mechanism most likely responsible for memory conformity is to warn participants that they may have been exposed to misinformation from their co-witness. Meade and Roediger (2002) found that the warnings significantly reduced the effect of the co-witness misinformation, but did not eliminate it, suggesting that some distortion of the original memory occurred. In another study, Wright et al. (2008) found that strict warnings (i.e., participants were told to recall items only if they were sure that they were accurate) reduced the effects of co-witness misinformation, but also had the deleterious effect of reducing the number of accurate details recalled. The third technique employed to identify the mechanism responsible for memory conformity is source monitoring (Lindsay & Johnston, 1989). Source monitoring tests give participants the option of saying that they remember an item only from the postevent suggestion, and not from the original stimulus. For example, participants in the current study were asked to indicate whether they remembered the item from the video only, from the discussion only, or from both the video and discussion. Although some studies have shown that source monitoring instructions such as these can eliminate the standard misinformation effect (Lindsay & Johnson, 1989; Zaragoza & Koshmider, 1989), other evidence suggests that co-witness contamination persists even when participants are asked to monitor the source of the information they recall (Meade & Roediger, 2002). In fact, Gabbert, Memon and Wright (2007) found that participants errantly attributed the source of their memory approximately 50% of the time. Discussion and Eyewitness Memory 7 While the studies described above (Meade & Roediger, 2002; Roediger et al., 2001) provide valuable insights into the mechanisms underlying memory conformity, they do have some limitations. First, in these studies there was only a short time delay (i.e. within the same testing session) between the presentation of misinformation and the memory testing. Real witnesses are commonly interviewed after longer delays (Wright & McDaid, 1996). This is important because source misattribution is more likely to occur after a longer delay. Underwood and Pezdek (1998) found that source information was less accurately reported after a delay of one month than after a tenminute delay. Thus, warnings and source monitoring instructions might be less effective if the duration of the delay more accurately reflected real eyewitness situations. Another limitation of these studies is their use of static photos as stimuli, which may reduce the ecological validity. Furthermore, in the studies described above (Meade & Roediger, 2002; Roediger et al., 2001), participants took turns recalling items, which restricted their communication in an artificial way. In particular, the social influence and persuasion likely to be part of real co-witness communication was absent. Finally, the ecological validity of co-witness studies is compromised by the use of confederates to supply the false information. Although this method allows the experimenters control over the false information which the participant is exposed to, confederates may not act like genuine co-witnesses. For example, confederates may have total confidence in the misinformation they supply, and may take a more dominant social role than real co-witnesses would. The present research aimed to improve on these limitations and increase ecological validity by having a longer delay period between co-witness discussion and individual testing, using videos to present a more realistic crime scenario, and by allowing more natural conversations between pairs of genuine witnesses. We Discussion and Eyewitness Memory 8 achieved this by showing pairs of participants what they believed were identical videos, but which actually differed in some details. Participants were then asked to discuss the stimulus event with one another in groups, some of which contained members who had seen different versions of the stimuli. Because the participants were unaware that they had seen different stimuli, their interactions with the group were likely to be more natural than those of delegated confederates. This methodology has been used in several studies of the effects of co-witness discussion on memory (e.g., Gabbert, Memon, & Allan, 2003; Garry, French, Kinzett, & Mori, 2008; Paterson, Kemp, & Ng, 2009; Wright, Self, & Justice, 2000). These studies have largely confirmed the results of studies using confederates, finding that participants who viewed different versions of the video erroneously recalled items from the alternative version of the stimulus when later giving their individual accounts. However, many studies using this improved methodology have not employed appropriate control groups. For example, some studies have compared participants who have seen different versions of the stimulus with individuals who have not discussed the event. This approach confounds the effects of discussing the event (e.g., the social presence of another, the elaboration and rehearsal of event-related memories) with the influence of the co-witness (i.e., the introduction of misinformation). There are also confounds when all participants have seen different versions of the stimulus than their partners and a comparison is made between items that differed between the two stimuli, and those that did not (e.g., carryover effects associated with within-subjects design). To improve on this methodology, we used “same-video” control groups (or “natural discussion” control groups as we will refer to them) in which all members of the group had seen the same version of the video Discussion and Eyewitness Memory 9 (either all Version A or all Version B). Using natural discussion groups as a control is critical because it allows us to distinguish between the effects of discussion and the effects of co-witness misinformation. Furthermore, it also allows us to identify positive as well as negative effects of discussion. For example, research on collaborative inhibition has shown that collaborative discussion groups typically recall less than non-interacting groups of pooled individuals (Weldon, Blair, & Huebsch. 2000). However, such group discussion can benefit memory when the group members are later tested individually. That is, people who had been collaborating in groups performed better on a final individual free recall task than those who had been in non-interacting nominal groups (Basden, Basden, & Henry, 2000). These natural discussion groups that do not involve the experimental introduction of postevent information (either by a confederate or any other method), have potentially the highest ecological validity, and yet few applied studies have employed such controls. Furthermore, those studies which have employed this natural discussion control group have yielded inconsistent results. Results from some experiments which do not artificially introduce postevent misinformation suggest that under certain conditions, group recall can have a beneficial effect on eyewitness testimony (e.g., Underwood & Milton, 1993; Yarmey & Morris, 1998), while others suggest that discussion prior to individual recall is not an advantageous procedure (e.g., Paterson, Kemp, & Ng, 2009; Stephenson, Abrams, Wagner, & Wade, 1986; Yarmey, 1992). The present research aimed to investigate effects of warnings, remember/know judgments and source monitoring on co-witness memory conformity following a oneweek retention interval and using an ecologically valid design that incorporates a Natural Discussion control group. Experiment 1 investigated the effects of warnings Discussion and Eyewitness Memory 10 and remember/know judgments on memory conformity and Experiment 2 investigated the effects of warnings and source monitoring judgments on memory conformity. Experiment 1 The first objective of Experiment 1 was to determine whether memory conformity is due to memory distortion or to other „source-tagged mechanisms‟ (Betz et al., 1996). To achieve this, participants in Experiment 1 received warnings that they may have been exposed to misinformation. These explicit warnings about misinformation were designed to help to reduce the experimental demand that may encourage conformity. It was hypothesised that, consistent with other studies (Betz et al., 1996; Gallo, Roberts & Seamon, 1997; Gallo, Roediger & McDermott, 2001; McDermott & Roediger, 1998; Meade & Roediger, 2002; Wright, 1993), memory conformity would be reduced, but not eliminated by the warning. Participants were also asked to make a remember/know judgment (Tulving, 1985) for each detail reported. In accordance with previous research (Meade & Roediger, 2002; Roediger et al., 2001) it was hypothesized that participants would be more likely to claim that they “knew” the items mentioned by the co-witness than to report that they specifically “remembered” seeing them. The second objective of the current study was to compare the memory of individuals who discussed the event with a co-witness who had seen a slightly different version of the eyewitness stimulus with the memory of individuals in natural discussion groups (who all saw the same stimulus), and also with individuals who had not discussed the event. In accordance with previously demonstrated results (e.g., Gabbert et al., 2001; Garry et al., 2008; Wright et al., 2000), it was hypothesized that individuals who discussed the event with a co-witness who had seen a different Discussion and Eyewitness Memory 11 version of the video would show less accurate memory than those in the natural discussion groups or those who did not discuss the event.