Confidence and Memory Accuracy: Do we know what we think we know? Bennett Brocka. University of Iowa

Transcription

1 Running Head: CONFIDENCE AND MEMORY ACCURACY 1 Confidence and Memory Accuracy: Do we know what we think we know? Bennett Brocka University of Iowa

2 Running Head: CONFIDENCE AND MEMORY ACCURACY 2 Abstract This paper focuses on the confidence/accuracy (CA) relationship in memory. A seemingly predictable correlation between a memory s accuracy and a person s subjective confidence in that memory has been shown to be quite fragile. Leippe (1980) provides evidence showing the potential disassociations between confidence and accuracy, noting that they can be altered independently and that suggests lawyers, judges and police officers to be aware of these effects when interviewing witnesses and evaluating evidence. Deffenbacher (1980) put forth a paper arguing that subjective confidence should not be used as a measure at all in court cases. In fact a multitude of newer research now indicates the weakness of subjective confidence and investigates particular methods of altering confidence or accuracy of a memory independently. This separation proves extremely important for legal cases in the matters of eyewitness testimony and even more everyday memory events. While interesting results have indicated the importance of the encoding process (Chua, Rand-Giovannetti, Schacter, Albert, and Sperling, 2004) and the bilateral parietal lobe (Simons, Peers, Mazuz, Berryhill and Olson, 2010) in the

3 Running Head: CONFIDENCE AND MEMORY ACCURACY 3 creation of confidence, the exact mechanism by which confidence is disassociated from accuracy is not known, however studies have discovered much worthy of deeper examination. Confidence and Memory Accuracy: Do we know what we think we know? Confidence subjectively feels like indicator of memory accuracy in our daily lives; the more sure we are of a memory s correctness, generally the more accurate we seem to turn out to be. But this confidence is purely subjective, so to what extent can it be trusted? Confidence in memory accuracy is not only important when remembering day to day details like a person s name or phone number, but it is still used as a barometer of accuracy in eyewitness testimony, where the outcome is much more important. Change-blindness related studies by Simons and

4 Running Head: CONFIDENCE AND MEMORY ACCURACY 4 Levin (1998) and Levin et al. (2002) serve as striking examples of poor eyewitness accuracy and serve as a good reason to question eye witness accuracy and perhaps more importantly, why inaccuracies occur even when confidence is high. While confidence has a weak predictive effect of accuracy, the effect is more restricted than one might expect. A correlation of +.41 was found between correct identification and confidence in the Sporer et al. study (1995). This however was only found in those subjects who had correct memories; no significant correlation was found between confidence and incorrect guesses, meaning this correlation is largely unhelpful in real world situations where there is no separate objective measure of accuracy. A further understanding of confidence is important in understanding this correlation though, and a number of theories explain confidence differently. A signal detection approach assumes that the distinction is similar to the old/new stimulus distinction, with Stretch & Wixted s study (1998) suggesting the criteria for confidence changes as accuracy changes; the clearer the distinction between accurate and inaccurate memories, the higher the confidence level. This model fits well with the apparent link between accurate memories and stronger confidence, but does not explain why they might diverge in some situations. Attribution theory is another perspective where confidence is related to attributing a memory to a past event where the more divergent a memory is from the remembered experience the less confidence the person has in the memory. (Jacoby, Kelley, & Dywan, 1989). Both of these theories are grounded in recognition processes however, where a study by Olsson and Juslin (1999) suggests that encoding is important for the creation of confidence, this is the basis for Chua et al. s 2004 neural imaging study of encoding. To test their hypothesis Chua et al. gathered 16 subjects and had them perform a series of remembering tasks, associating

5 Running Head: CONFIDENCE AND MEMORY ACCURACY 5 names with faces. Later the subjects were tested on the associations with a forced yes/no response and subjects were asked whether they had high or low confidence in their accuracy. Generally subjects were more correct than not, even when reporting low confidence, but the study was more concerned with the cases where high confidence was attributed to an incorrect response. Subjects underwent fmri imaging during encoding, and the differences between high confidence and low confidence were examined to discern any differences in neural activation. Certain activation in the left frontal gyrus was found to be associated with high confidence regardless of accuracy, suggesting it is important for subjective confidence. Additional activation of the left frontal gyrus was noticed in high confidence incorrect responses, diverging from high confidence correct situations, indicating that this difference during encoding is related to the separation of accuracy and confidence, as was hypothesized. Additionally, certain medial temporal lobe (MTL) activation was associated with only correct and high confidence associations. These results give us a clue as to how memory and confidence dissociate, but they are not a practical means of investigating whether a particular confident memory is also accurate; this could only be inferred from an fmri image during the encoding process, which is impossible in any practical situation. However Chua et al. s 2004 study was, in their estimation, the first study to examine neural images during encoding for the purposes of memory confidence, so it is possible more directly useful evidence could be found. However, if the difference in confidence and accuracy is only represented neutrally during encoding, it seems unlikely if a clear neural difference could be distinguished from a neural image taken only during recall. Discouragingly,

6 Running Head: CONFIDENCE AND MEMORY ACCURACY 6 this could mean there is no way to determine whether an already formed memory is accurate or not. Despite the findings regarding the MTL s involvement in confidence in Chua et al. s 2004 study, Simons et al. s 2010 study found significant evidence of the importance of the parietal lobe s importance in confidence. Simons et al. tested patients with bilateral and unilateral parietal lobe lesions against healthy controls. The bilateral lesion patients were found to have no significant difference in ability to recall accurately in a recall task, but consistently reported significantly lower confidence in their recall relative to controls or unilateral parietal lobe lesion patients. Interestingly, the patients recall accuracy has been consistently similar to controls recall ability despite the fact that the lesion areas of the patients closely match the areas activated in the healthy control s parietal lobe during recall. A possible explanation of the reduced confidence in the bilateral lesion patients is that they would be less confident in their cognitive abilities overall, but Simons et al. dismiss this as the unilateral lesion group did not have this same confidence deficit, despite being matched for lesion size, and in addition the bilateral lesion patients showed normal levels of confidence in recognition tasks. Instead Simons et al. posit that the bilateral lesion patients may have a deficiency of the vivid episodic detail present in healthy controls (also suggested by studies by Lyle and Johnson 2006, 2007). This hints at an important role of the parietal lobe in episodic memory. Shifting from the neurological basis of confidence and accuracy to the functional basis, one of the most significant causes of reduced memory accuracy is misleading post-event information (MPI), as described by Koriat, Goldsmith, and Pansky (2000). In a laboratory MPI paradigm, subjects will be exposed to an event or bit of information, later misled about a

7 Running Head: CONFIDENCE AND MEMORY ACCURACY 7 particular detail (often by asking leading questions ) and subsequently tested, subjects memories typically show impairment about the detail they were misled about. Interestingly the MPI effect seems strongest when the misleading information is presented in a way that suggests a subject to recall the original event, possibly meaning the misleading detail is integrated with the original memory. MPI is perhaps most dangerous as subjects often associate high confidence with the false memories created due to MPI (Zaragoza and Mitchell 1996). MPI is also interesting in that it appears to have developmental and age related components, suggested both by Koriat et al. (2000) and a study on developmental effects on the CA relationship by Howie and Roebers (2007). Howie and Roebers found many interesting results regarding subjective confidence in children. Children (test groups of 8 and 10 years of age) were generally found to have a poorer internal CA calibration when presented with misleading questions in trials, where adults remained more accurate in their confidence calibrations in these situations. This suggests that the questioning of children must be handled especially carefully and that their confidence ratings might be considered less accurate. Children performed as well as adults in these tests when given only unbiased, not misleading questions, but in real world applications the control over misleading and non-misleading questions cannot be assumed. While the effect of misleading information on confidence appears stronger in children, a misinformation effect in the elderly appears present as well. A study by Jacoy et al... (2005) showed that older adults (age 64 to 87) were ten times more likely to produce a false memory than younger adults (18-27) after being presented with misleading information (this is also discussed in Koriat et al. 2000).

8 Running Head: CONFIDENCE AND MEMORY ACCURACY 8 Knowing the CA disassociation appears to have its root in encoding (as suggested by Chua et al. 2004), it is encouraging to find that it does appear possible to reduce the misinformation effect on memory accuracy during the encoding process, albeit with very through encoding and an abundance of retrieval cues. Frost and Weaver s 1997 study showed that memory distortions resulting from misleading information could be reduced or eliminated in very specific encoding and retrieval environments. Frost and Weaver admitted more research could be done to examine why and which retrieval cues proved helpful for this effect, as this study only examined the number of cues. Subjects experienced different encoding lengths and experienced a complex visual scene; they were encouraged to process the images thoroughly. Subjects were then exposed to a test for the purpose of misinformation; certain test questions offered only incorrect answers. Later a final test was given with questions containing varying amounts of cues regarding the critical information. The misinformation significantly reduced accuracy, but this effect was largely (but not completely across all subjects) reduced in the groups that were given more retrieval cues in their final tests. Odinot and Wolters (2006) conducted a separate study on the effects of retrieval interval and repeated recall on the CA relation. Subjects were presented a stimulus event visually and tested on recall of the event a period of time later, and certain groups of participants had more or less (between one and three tests total). Neither confidence nor accuracy changed significantly between any of the recall count or retention interval groups. Mean confidence scores reduced slightly in the longest retention interval group, but the decrease was not statistically significant. Between these two experiments it appears that while number of cues and depth of encoding may have an effect, repeated recall does not have a significant effect. Frost and Weaver (1997) suggest interference is a main (but potentially not the only) mechanism by which MPI reduces

9 Running Head: CONFIDENCE AND MEMORY ACCURACY 9 memory accuracy, which would explain why more retrieval cues limited the effect of MPI by compensating for interference. Repeated recall and longer retention intervals such as in the Odinot and Wolters 2006 study should not reduce interference or add additional cues, which could be why no increase in accuracy was found. An issue potentially related to number of cues (explained below) is the Consentuality Principle suggested by Koriat (2008). The Consentuality Principle is explained by Koriat as the tendency for a particular subject s confidence in response to be related to whether the answer matches the general consensus (most common response, whether correct or incorrect) of the subjects responses. This was tested in a paradigm where subjects were tested on vocabulary in a language known by all subjects (Hebrew), where some of the words were prescreened to be more difficult than others, due to a misleading relationship between the word s structure and actual meaning. Subjects were more confident when giving the same response as most of the other subjects, and less confident when their answer diverged, all independent of objective accuracy. While the term consentuality implies a social component, subjects had no interaction with each other and had no way of knowing what answer the other subjects would choose, so Koriat s Consentuality Principle seems to be more based in what most people would think the correct answer would be. This is more likely related to an internal evaluation of the memory trances present and memory cues presented, as many of the subjects came to both same answer (correct or not) and confidence level despite the lack of interaction between subjects. This has interesting implications in that it backs up the importance of misleading suggestions in confidence (as implied in Koriat et al. 2000); some trials were prescreened to be more difficult than others due to conflicting information between the word and meaning. Misleading trials caused most subjects to respond incorrectly yet subjects maintained a high level

10 Running Head: CONFIDENCE AND MEMORY ACCURACY 10 of confidence. This could hint at the basis of confidence; Koriat suggests confidence judgments are based on the number of clues (cues) toward a potential response, rather than the traceaccess theory which assumes confidence is based on access to the presence and strength of memory traces for the knowledge (Hart, 1965). This could tie into the findings by Frost and Weaver (1997) in that they suggested misinformation could be rooted partly in inhibition; inhibition would limit the number of (active) cues toward a certain memory in the case of misinformation regarding that memory resulting in an inaccurate recollection. Koriat s study suggests this reduction of accuracy does not correspond to a reduction in confidence. It should be kept in mind however that Koriat s 2008 study focused on general or semantic knowledge (vocabulary of a language known by the subjects) rather than eyewitness reports, which are more episodic in nature and are the subject of many studies regarding confidence in memory. Eyewitness reports are based on personal knowledge and thus would not have consentuality in the same way general knowledge questions do as there is no group to check one s personal memory against, but the confidence estimation may function very similarly to consentuality as shown in Koriat s study appears based in internal processes resulting from the information presented, not any social effects. Considering the numerous ways confidence and accuracy become disassociated in individuals, it seems quite clear that confidence cannot be used as a practical measure of accuracy, especially in the case of eyewitness testimony. This subjective experience does not appear rooted in direct access to an accurate memory but is instead based on something that may generally relate with completeness or accuracy, such as number of retrieval cues as suggested by Koriat (2008). Unfortunately eyewitness testimony is still often considered valuable by jurors

11 Running Head: CONFIDENCE AND MEMORY ACCURACY 11 and/or judges despite all of this research, with 45% of judges incorrectly disagreeing with factually based statements about eyewitness testimony (Wise and Safer 2004). More encouragingly however there are many avenues to study the CA relationship and where they might diverge, the MTL (Chua et al. 2004) and the parietal lobe (Simons et al. 2010) appear significant in different ways to the CA relationship. The causal mechanism behind the subjective feeling of confidence still requires investigation as well, however there some factors which may result better calibrated CA relationships, such as certain ages (Howie and Roebers 2007, Jacoby et al. 2005) and longer encoding times (Frost and Weaver 1997). There is much left to be learned about the nature of confidence in one s memories, and with current research there are many factors in confidence to further explore, such as the potential Consentuality Principle (Koriat 2008) which hints at the importance of number cues, similar to Frost and Weaver s (1997) research in overcoming misinformation. References: Baddeley, A., Eysenck, M. W., Anderson M. C. (2009). Memory. New York: Psychology Press.

12 Running Head: CONFIDENCE AND MEMORY ACCURACY 12 Brewer, Neil; Wells, Gary L. (2006). The confidence-accuracy relationship in eyewitness identification: Effects of lineup instructions, foil similarity, and target-absent base rates. Journal of Experimental Psychology: Applied, 12(1), doi: / X Chua E. F., Rand-Giovannetti E, Schacter D. L., Albert M. S., Sperling R. A. (2004). Dissociating confidence and accuracy: functional magnetic resonance imaging shows origins of the subjective memory experience. Journal of Cognitive Neuroscience. 7, Deffenbacher, K.A. (1980). Eyewitness accuracy and confidence. Law and Human Behavior. 4, 4, Frost, P., & Weaver, C. A., III. (1997). Overcoming misinformation effects in eyewitness memory: Effects of encoding time and event cues. Memory, 5, Howie, P. and Roebers, C. M. (2007). Developmental progression in the confidence-accuracy relationship in event recall: insights provided by a calibration perspective. Applied Cognitive Psychology, 21: doi: /acp.1302 Jacoby, L. L., Bishara, A. J., Hessels, S., Toth, J. P. (2005). Aging, subjective experience, and cognitive control: Dramatic false remembering by older adults. Journal of Experimental Psychology: General, 134, Koriat, A. (2008). Subjective confidence in one's answers: The consensuality principle. Journal of Experimental Psychology: Learning, Memory, and Cognition, 34(4), doi: / Koriat A., Goldsmith M., Pansky A. (2000). Toward a psychology of memory accuracy. Annual Review of Psychology. 51, Kunimoto, C., Miller, J., Pashler, H. (2001). Confidence and Accuracy of Near-Threshold Discrimination Responses. Consciousness and Cognition. 10, 3,

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14 Running Head: CONFIDENCE AND MEMORY ACCURACY 14 Wise, R. A., Safer, M. A. (2004). What US judges know and believe about eyewitness testimony. Applied Cognitive Psychology, 18: doi: /acp.993 Zaragoza, M. S., Mitchell, K. J. (1996). Repeated exposure to suggestion and the creation of false memories. Psychol. Sci. 7: