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This article was downloaded by: [Texas A & M International University] On: 06 October 2014, At: 08:22 Publisher: Routledge Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK Memory Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/pmem20 Memory conformity affects inaccurate memories more than accurate memories Daniel B. Wright a & Daniella K. Villalba a a Psychology Department , Florida International University , Miami , FL , USA Published online: 27 Feb 2012. To cite this article: Daniel B. Wright & Daniella K. Villalba (2012) Memory conformity affects inaccurate memories more than accurate memories, Memory, 20:3, 254-265, DOI: 10.1080/09658211.2012.654798 To link to this article: http://dx.doi.org/10.1080/09658211.2012.654798 PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http://www.tandfonline.com/page/terms-and-conditions

Memory conformity affects inaccurate memories more than accurate memories

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This article was downloaded by: [Texas A & M International University]On: 06 October 2014, At: 08:22Publisher: RoutledgeInforma Ltd Registered in England and Wales Registered Number: 1072954 Registered office: MortimerHouse, 37-41 Mortimer Street, London W1T 3JH, UK

MemoryPublication details, including instructions for authors and subscription information:http://www.tandfonline.com/loi/pmem20

Memory conformity affects inaccurate memoriesmore than accurate memoriesDaniel B. Wright a & Daniella K. Villalba aa Psychology Department , Florida International University , Miami , FL , USAPublished online: 27 Feb 2012.

To cite this article: Daniel B. Wright & Daniella K. Villalba (2012) Memory conformity affects inaccurate memoriesmore than accurate memories, Memory, 20:3, 254-265, DOI: 10.1080/09658211.2012.654798

To link to this article: http://dx.doi.org/10.1080/09658211.2012.654798

PLEASE SCROLL DOWN FOR ARTICLE

Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”)contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensorsmake no representations or warranties whatsoever as to the accuracy, completeness, or suitabilityfor any purpose of the Content. Any opinions and views expressed in this publication are the opinionsand views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy ofthe Content should not be relied upon and should be independently verified with primary sources ofinformation. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands,costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly orindirectly in connection with, in relation to or arising out of the use of the Content.

This article may be used for research, teaching, and private study purposes. Any substantial orsystematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distributionin any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found athttp://www.tandfonline.com/page/terms-and-conditions

Memory conformity affects inaccurate memories morethan accurate memories

Daniel B. Wright and Daniella K. Villalba

Psychology Department, Florida International University, Miami, FL, USA

After controlling for initial confidence, inaccurate memories were shown to be more easily distorted thanaccurate memories. In two experiments groups of participants viewed 50 stimuli and were then presentedwith these stimuli plus 50 fillers. During this test phase participants reported their confidence that eachstimulus was originally shown. This was followed by computer-generated responses from a bogusparticipant. After being exposed to this response participants again rated the confidence of their memory.The computer-generated responses systematically distorted participants’ responses. Memory distortiondepended on initial memory confidence, with uncertain memories being more malleable than confidentmemories. This effect was moderated by whether the participant’s memory was initially accurate orinaccurate. Inaccurate memories were more malleable than accurate memories. The data were consistentwith a model describing two types of memory (i.e., recollective and non-recollective memories), whichdiffer in how susceptible these memories are to memory distortion.

Keywords: Eyewitness testimony; Distortion; Memory conformity.

After two people have experienced an event, they

often discuss details of the event with each other.

This discussion can affect what each person later

reports about the event. Much research has shown

how different social and cognitive processes can

lead people to report what another person said

rather than what they saw themselves (for reviews

see Blank, 2009; Harris, Paterson, & Kemp,

2008; Rajaram & Pereira-Pasarin, 2010; Sutton,

Harris, Keil, & Barnier, 2010; Wright, Memon,

Skagerberg, & Gabbert, 2009). This is known as

the social contagion of memory (Roediger,

Meade, & Bergman, 2001), or memory confor-

mity effect (Wright, Self, & Justice, 2000). Follow-

ing Roediger (2010), we will use the phrase

memory conformity to refer to the situation in

which a person’s response to a memory question

is affected by what another person said. The

current studies examine how initial memory

confidence relates to susceptibility to memory

conformity and test whether this relationship

depends on initial memory accuracy. We will

discuss why initial memory confidence should be

related to memory conformity, and why memory

accuracy may moderate this effect.There are two routes to memory conformity:

the normative influence route and informational

influence route (Baron, Vandello, & Brunsman,

1996; Wright, London, & Waechter, 2010). Nor-

mative influences occur when people report the

same information as others even when they

believe the information is incorrect. They do

this in order to gain approval and feel part of

the group. Normative influences are most likely

to occur when the responses are made in the

presence of another person and when the cost of

Address correspondence to: Daniel B. Wright, Psychology Department, Florida International University, 11200 S.W. 8th Street,

Miami, FL, 33199, USA. E-mail: [email protected]

Thanks to Carmen Barresi, Osvaldo De la Cruz, Joemy Familia, Erika Fountain, Holly George-John, Andrew Quinn, Alyssa

Ruiz, Jessica Sardinas, Roxana Soriano, and Dave Tamola for data collection and data entry.

MEMORY, 2012, 20 (3), 254�265

# 2012 Psychology Press, an imprint of the Taylor & Francis Group, an Informa businesshttp://www.psypress.com/memory http://dx.doi.org/10.1080/09658211.2012.654798

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disagreeing is higher than the value of beingcorrect (Baron et al., 1996). An example iswhen one member of a family is recounting anevent at a holiday party, errantly reports incon-sequential details, and asks for another person’sagreement. Because the cost of disagreeing islikely to be high compared with the cost ofaccuracy, the person may choose not to correcttheir relative.

Informational influences arise when somebodycompares beliefs about their own memories withbeliefs about other people’s memories. Thesebeliefs are combined into a new belief about theevent. When people are uncertain in their ownmemories they should be more influenced byother people’s responses (Deutsch & Gerard,1955). As an example, suppose a group ofstudents are preparing for an exam. If a weakstudent thinks their teacher said, ‘‘Orlando is thecapital of Florida’’, but hears a strong student saythe teacher said, ‘‘Tallahassee is the capital ofFlorida’’, the non-attentive student may believethis information to be correct and report thisinformation on a subsequent test.

The current experiments focus on the informa-tional route to memory conformity. Informationalinfluences can lead to memory conformity whenpeople are unsure about their own memory andthey trust another person’s memory more thantheir own (see Carlucci et al., 2011; Gabbert,Memon, & Wright, 2007). If people trust some-body else’s memory more than their own, they aremore likely to incorporate the other person’sreport in response to a memory question than ifpeople believe their own memory to be correct.Empirical backing for this has come from severalstudies. For example, Schneider and Watkins(1996) had two people take a memory recognitiontest together so that the second person knew howthe first person responded. They found not onlythat the second person was affected by what thefirst person said, but that they conformed mostwhen the first person was confident. Similarly,Wright et al. (2000) had two participants viewnearly identical sets of photographs depicting atheft. They were initially questioned individuallyabout photographs including the critical differ-ence and each made a confidence rating. Next,the pair discussed the story including the criticaldifference and came to an agreement about theevent details. In almost all groups the pair wentwith the memory of the person who initiallyexpressed more confidence.

The results of these studies show that is itimportant to take into account how confident theother person appears. If another person appearsconfident, the work by Schneider and Watkins(1996), Wright et al. (2000), and other studiesshow that this person’s report is more likely toaffect other people’s memory reports than if theperson does not appear confident. This is similarto how social psychologists claim people’s atti-tudes may change when encountering a discre-pant attitude: the shift depends on the strength ofthe belief (Fishbein & Ajzen, 1975). Withinattitude research, if someone holds a moderateview towards an issue and is presented with anargument strongly in favour of the issue, theperson’s attitude tends to become more positive.Similarly, if a person believes that an item wasshown, but is uncertain, and is presented withinformation suggesting that the item certainly wasshown, this should increase the conviction theperson has that the item was previously shown. Avery simple model would be that the shift dependson how different the person’s memory is from theother person’s memory (larger discrepancies pro-ducing larger shifts) and how certain the person isin their own memory (uncertain memories aremore malleable).

It is worth making clear that the model inFigure 1 is being presented as a straw-manproposal to help identify why data are likely toshow a more complex pattern. Figure 1 shows thismodel for an old/new recognition test with sevenlevels of confidence, from confident the presenteditem was not shown (i.e., new) to confident thepresented item was shown (i.e., old). Values alongthe x-axis refer to the confidence the secondperson initially has about whether the presenteditem was previously shown or not. Values on theleft mean the person initially believes the itemwas not shown, and values on the right mean theperson initially believes the item was shown. Thedifferent lines refer to the confidence expressedby the first person responding. The darkest linerefers to when the other person confidentlyreports the item was not previously shown. Thelightest line refers to when the other personconfidently reports the item was previouslyshown. Intermediate levels of confidence areshown with intermediate levels of grey.

On the y-axis is the amount the person’smemory shifts from their initial confidence totheir confidence after discovering the other per-son’s belief. The higher the value, the more theperson moves towards believing the item was

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previously shown. When participants are initiallyvery confident in their memories (at the twoends), these beliefs may not change or may shiftonly slightly depending on what another personsays. This is shown by the short arrows labelled‘‘a’’ in Figure 1. When the initial memory isuncertain, what another person says should have alarger effect on participants’ memories. This isshown with the long arrow labelled ‘‘b’’ in Figure1. The shifts are larger when the other person’sbelief is expressed with high confidence.

There are two technical aspects of Figure 1 thatare worth discussing. First, the lines are allstraight. Within statistics this is sometimes calleda ‘‘broken-stick’’ model (Ruppert, Wand, &Carroll, 2003). There are no a priori reasons tobelieve that straight lines should be preferred tocurves, but this simplifies the statistics (and forour data more complex curves did not improvethe fit). The model is shown with straight lines forconvenience rather than for making any definitiveclaim that the relationship is linear. The second

aspect is more relevant to memory theorising. Theangles of the lines are the same on the top andbottom of the graph, and on the left- and right-hand sides of the graph. This implies that the sizeof the memory conformity effect is the same forwhen the other person says ‘‘old’’ as for when theother person says ‘‘new’’, and is the same regard-less of whether the participant initially believesthe item is a target or a filler. We examinedwhether this model can account for our data.

There are reasons to believe that the memoryconformity effect will be moderated by whetherthe item is a filler or a target and whether theother person says ‘‘old’’ or ‘‘new’’, and thereforethat the model in Figure 1 may be rejected. First,there are data showing that the size of thememory conformity effect depends on whetherthe item was original shown. For example,Wright, Mathews, and Skagerberg (2005) foundthat the memory conformity effect was abouttwice as large for creating new memories forpreviously unseen fillers compared with making

Other person says old (previously shown)

Other person says new (not previously shown)

Most confident

Most confident

Least confident

Least confident

a ab

Definitely new

Tow

ards

new

Tow

ards

old

No

chan

ge

Shi

ft in

mem

ory

Definitely oldUncertainInitial memory

Figure 1. A straw-man model of the shift in memory due to memory conformity for different levels of initial certainty. The short

arrows ‘‘a’’ show small memory conformity effects for memories that are certain, and the long arrow ‘‘b’’ shows a large memory

conformity effect for initially uncertain memories. The slopes of all the lines assume the memory conformity effect is the same for

new and old items.

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people not report a target that they had seen (butsee Merckelbach, Van Roermund, & Candel,2007).

Second, there are theoretical reasons to believethe memory conformity effect may differ for fillersand targets. Many memory researchers describetwo types of subjective memory experience. Theseare often described as a sense of familiarity and asense of recollective re-experiencing (for a review,see Yonelinas, 2002). Recollective memories areoften described as episodic or pictorial memories,where during the recollection people can relive, intheir mind’s eye, the event they are remembering.Non-recollective events lack this re-living aspect.These types of memories are relevant to the currentpaper because recollective memories tend to beheld with more confidence than non-recollectivememories, and they tend to be less malleablethan non-recollective memories (Brainerd &Reyna, 2005).

Recollective processes can be used both tostate that a target was previously shown and tostate that a filler was not shown. Positive recollec-tions of targets occur in many recognition studies.This is the memory process of mentally re-living apast event. Recollecting in order to reject a teststimulus is more complicated. Gallo (2004) de-scribes two recollective processes that can be usedto reject a filler. First, disqualifying recall-to-rejectis when a participant recalls something other thanthe test item which allows them to infer that thetest item was not presented. For example, suppose

a person is shown a video of a man wearing acowboy hat and is later asked if the man waswearing a baseball hat. If the person recollects thecowboy hat, the person can state that the man wasnot wearing a baseball hat. This requires both apositive recollective memory for the cowboy hatand an inference, knowing that if cowboy hat wasworn then a baseball hat was not worn. Theinference part of disqualifying recall-to-rejectsrequires certain characteristics of the stimuli,which are unlikely to occur very often unless thestimuli and test instructions are specifically de-signed to allow this type of processing.

The second process Gallo (2004) describes isdiagnostic recall-to-reject. This is where a personis presented with a test item and believes that if ithad been presented originally then they wouldhave a recollection of it. This is a meta-memoryprocess. For example, suppose a person is shown50 non-distinctive faces, and then at test one ofthe photographs shows someone with bright greenhair. The person would state that this picture wasnot previously shown because if it had been theywould have recollected it. Diagnostic recall-to-reject should occur in most memory recognitionstudies, but still be less common than positiverecollections.

How does taking into account these two typesof memory affect the predictions for the memoryconformity shift? Figure 2 shows hypotheticaldistributions for recollective and non-recollectivememories. For fillers about half of the correct

Fillers Targets

Recollective

Familiar

Some low scoresmalleable and somenon-malleable

Most high scoresnon-malleable

Almost all highscores malleable

Almost all lowscores malleable

Recollective

Familiar

Initial belief

–3 –2 –1 0 1 2 3

Initial belief

–3 –2 –1 0 1 2 3

Figure 2. Hypothetical distribution for recollective and non-recollective memories by initial belief.

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highly confident responses (on the left side of theleft panel) are recall-to-reject items, so we wouldexpect many of these not to be malleable.However, almost all of the highly confident errorswill be based on non-recollective processes.Therefore these are more likely to be malleable.For targets there is likely to be a large number ofhighly confident accurate hits. A large percentageof these are likely to be recollective and thereforerelatively immune from distortion. This compareswith the highly confident but errant misses. Theexpectation is that few of these will be based onrecollective processes and thus will be malleable.

If it is assumed (1) that recollective and non-recollective memories are distributed roughly asdepicted in Figure 2, although the straight linesfor non-recollective responding are used just forillustration, and (2) that recollective memoriesare unlikely to be change (very much), then thereshould be sizeable memory conformity shifts forconfident errant memories, some memory con-formity for accurate confident beliefs that a newitem is new, and only small memory conformityeffects for accurate confident memories for olditems.

Two experiments are conducted to assesswhether the memory conformity effect is moder-ated by initial beliefs and whether the memory isaccurate or not. The difference between the twoexperiments is whether the encoding conditionswere designed to promote future recollectiveexperiences. In the first experiment stimuli werepresented for 3 seconds and in colour, while in thesecond experiment stimuli were presented foronly 1 second and in monochrome. Much researchshows increased recollections with longer encod-ing durations (e.g., Yonelinas, 2002). Further,when the colour is diagnostic of the objects thishas been shown to improve memory (for review-see Bramao, Reis, Petersson, & Faısca, 2011). Ifthese manipulations affect the proportionsof recollective memories then these should bereflected in asymmetries in the memory confor-mity effect.

It is important to stress that the main researchgoal is to explore the role played by initialmemory belief on subsequent memory confor-mity. Therefore it is necessary to measure peo-ple’s beliefs about their own memories before andafter they are presented with other people’sreports. This differs from the standard socialrecognition test where people are only askedabout their memories after being presentedwith another person’s report (e.g., Schneider &

Watkins, 1996; Skagerberg & Wright, 2008a;Wright & Carlucci, 2011; Wright et al., 2005).

In summary, the experiments examine how aparticipant integrates someone else’s memorybelief with their own. It is predicted that partici-pants will be influenced by the other person andthat this influence will depend on the participant’sinitial confidence and the confidence expressed bythe other person. Most critical to the currentexperiments, we hypothesise that these effects willbe moderated by whether the initial memory isaccurate or inaccurate. Recollective memories, bothpositive and diagnostic recall-to-reject memories,tend to be accurate and less malleable. Thereforewe predict that, after controlling for initial memoryconfidence, inaccurate memories will be more easilydistorted than accurate memories.

EXPERIMENTS 1 AND 2

The method used in the present studies is a socialrecognition test procedure based on Schneiderand Watkins (1996; see also Wright et al., 2005),but with memory belief measured both beforeand after what the other person supposedlyreports. The social recognition test procedureinvolves presenting participants with a largenumber of stimuli and then having them takepart in a memory recognition test on these plussome fillers. Sometimes the other person, whomay be a confederate or another participant, ispresent and sometimes participants are just toldthe responses of the other person. Here we opt forthe latter approach. The additional aspect that weuse in the current experiments is that participantsprovide their memory belief both before and afterhearing the other person’s response. This allowsus to examine the relationship between memorybefore the suggestion and the effects of memoryconformity. The two experiments conducted havesimilar designs so are reported together. Thepurpose of conducting two experiments was totest if the pattern of results replicates with adifferent level of encoding quality.

Method

Participants. Participants for both experimentswere recruited through the Florida InternationalUniversity’s psychology online participant pooland received 1 credit-hour for their partici-pation. Experiment 1 had 117 participants and

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Experiment 2 had 137 participants. No participantcompleted both experiments. Most of the partici-pants were female (66% and 73% in Experiments1 and 2 respectively) and Hispanic (74% and 70%in Experiments 1 and 2 respectively). The meanages were 20 and 21 years old for Experiments 1and 2, respectively.

Design. Both experiments used a within-participants design with participants making twomemory ratings for each of 100 test trials(50 for fillers, 50 for targets). After their initialmemory ratings of the stimuli (on a 7-point scale),participants were shown the other person’s mem-ory strength response (with each of the sevenvalues used approximately equally), followed bythe participant’s final memory rating.

Materials. A set of 100 cartoon-like drawingswere taken from a large database of images(Nova Development, 2004). In Experiment 1these were in colour and in Experiment 2 theywere changed to greyscale. The purpose of thischange was to make the stimuli in Experiment 2less memorable, as discussed earlier.

Procedure. Participants arrived at the labora-tory in groups of two or three and sat down atcomputer workstations, which were separated bydividers so that participants could not see eachother. All participants viewed the same set of 50images, which were presented in random orderusing the software SuperLab. In Experiment 1the drawings were shown for three seconds eachand in Experiment 2 they were shown for onesecond each. The change in presentation timeswas done to make the stimuli in Experiment 2less memorable than in Experiment 1. The inter-stimulus rate was one second for both experi-ments.

After participants had seen the 50 images theywere told that they were paired with anotherparticipant who had seen the same drawings buthad participated in the study at an earlier time. Inreality participants were not paired with anotherperson and the responses were computer gener-ated. Participants were told they would be showna set of drawings, some of which they had seenbefore (targets) and some of which were new ones(fillers). They were to use a seven-button re-sponse pad to indicate on a 7-point scale whetherthey thought each drawing was one they had beenshown before or not (1�definitely new,4�uncertain, 7�definitely old). For each itemparticipants made their initial response, four

seconds elapsed, participants were shown theresponse for the other person, another fourseconds elapsed, and then they provided theirfinal response. They were explicitly told that theycould change their response if they wished. Theexact instructions were:

Now, you are going to be shown 100 picturesand then you have to decide which pictures youhave seen before and which ones you haven’t.Use the response pad to input your answers.Then the computer is going to show you how aprevious participant responded for each of thepictures. The computer is able to do this bygoing into a database and pulling out informa-tion from a random person who completed thestudy before you. You input your answer onceand then after the computer shows you theresponse from this other person, you will beallowed to change your answer if you choose to.If you want to keep the same answer then justhit the same button. If you have any questionsplease let me know. You may begin.

Results

The results are divided into three sections. First, inorder to measure initial accuracy we comparedinitial memory ratings for fillers and targets.Because there are multiple participants viewingmultiple drawings, cross-classified models wereused for all analyses (Baayen, Davidson, & Bates,2008; Bates & Maechler, 2010; Wright & London,2009). Details of this method are provided in theappendix. For all analyses the intercept is allowedto vary by participant and by drawing. The memoryvariables were scaled from �3 to �3 with 0corresponding to uncertainty. Second, to measurethe size of the memory conformity effects, partici-pants’ second responses were predicted from (a)their first responses, (b) whether the item was atarget, and (c) the other person’s responses. Third,we examined the relationship between initialmemory confidence and memory conformity. Inter-actions are examined to test if the effect sizes aresimilar for accurate and inaccurate memories.

Initial memory recognition. To measure initialmemory accuracy, whether the item was pre-viously shown or not was used to predict initialmemory ratings. This is similar to conducting a t-test, but taking into account that participants saw

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100 test items. If participants have no memory forany of the items then one would expect the meanfor previously unseen fillers to be approximatelythe same as the mean for previously seen targets.If participants have memory, then the predictionis that ratings should be higher for target than forfillers. Further, because zero is the midpoint onthe scale, the prediction is that the mean for fillersshould be negative and the mean for targetsshould be positive.

In Experiment 1 the mean for fillers, �1.93(SD�1.77), was much lower than the mean fortargets, 1.82 (SD�2.08). The difference,3.91 (SE�.03), is statistically significant, x2(1)�9002.47, p B.001. The corresponding numbers forExperiment 2 were: mean for fillers, �1.53(SD�1.89), mean for targets, 1.44 (SD�2.20),and the difference, 2.97 (SE�.03), is also statis-tically significant, x2(1)�6100.81, p B.001. The3.91 and the 2.97 show that people could remem-ber the items. Note also that, as predicted, thedifference is greater for Experiment 1, which hadthe better encoding conditions.

Measuring memory conformity. Memory con-formity is measured by the effect of the otherperson’s response on the participant’s response.Because participants provided a memory re-sponse both before and after receiving informa-tion about another person’s response, the initialresponse can be used as a covariate. Memoryconformity for each experiment can be measuredwith the following model:

Response2 ¼ b0 þ b1 Response1 þ b2 Other

See the Appendix for details of the statisticaltechnique. The estimate of b2 measures memoryconformity. If what the other person reports hasno effect on what the participant reports, then b2

should be approximately zero. This is the nullhypothesis, H0: b2�0, which corresponds with nomemory conformity. If the participant tends toconform with the other person’s report, theprediction is that b2 should be greater thanzero. For Experiment 1, b2�.089 (SE�.004).For Experiment 2, b2�.120 (SE�.004). Thusmemory conformity is evident for both experi-ments. As predicted, the memory conformityeffect is larger for Experiment 2, where theencoding conditions were worse.

Does initial confidence predict memoryconformity? Before discussing the statistical mod-els it is worth presenting some descriptive statis-

tics that do not take into account participants’initial confidence, but only whether they wereinitially accurate or inaccurate. In Experiment 1,when the participant initially was correct and theresponse from the other person was incorrect,the participant shifted to uncertain 4% of thetime and shifted to the incorrect response 2%of the time. In Experiment 2, when the participantinitially was correct and the response from theother person was incorrect, the participant shiftedto uncertain 7% of the time and shifted to theincorrect response 3% of the time. In Experiment1, when the participant initially was incorrect andthe response from the other person was correct,the participant shifted to uncertain 12% of thetime and shifted to the correct response 10%of the time. In Experiment 2, when the participantinitially was incorrect and the response from theother person was correct, the participant shiftedto uncertain 13% of the time and shifted to thecorrect response 9% of the time. Thus incorrectbeliefs were more likely to be corrected thancorrect beliefs were to be made erroneous.

To analyse the relationship between initialmemory confidence and memory conformity,and to see whether the relationship differs foraccurate and inaccurate memories, a more com-plex model was evaluated. This was conductedseparately for Experiments 1 and 2 and the resultsare presented graphically. The second response ispredicted from the initial response, what the otherperson said, and whether the item was a filler or atarget. Interactions with what the other personsaid are used to test if the initial responsemoderates the size of the memory conformityeffect. The initial response is fit by two straightlines joined at the 0-point (the broken-stickmodel; Ruppert et al., 2003). This method allowsus to examine whether the memory conformityeffect is less for uncertain initial responses thanfor those made with confidence.

The model shown in Figure 1 assumes thememory conformity effect is the same for accu-rate and inaccurate memories and for fillers andtargets. As discussed in the introduction it ispredicted this simple model would not accountfor the data. A three-way interaction would showthat the memory conformity effect is moderatedby whether the initial memory is accurate. Thethree-way interaction among initial response,whether the item is a target, and the otherperson’s response, was statistically significant forExperiment 1, x2(2)�90.88, p B.001. Figure 3shows the predicted memory conformity shift (the

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predicted response at time 2 minus the initial

response) with the initial response for Experi-

ment 1. The other person’s responses are shown

with lines of different shades of grey. The lightest

line (at the top) is when the other person’s

response was the most confident that the item

was a target, and the darkest line (at the bottom)

is when the other person’s response was the most

confident that the item was a filler. The shifts are

shown separately for fillers and targets.The memory conformity effect is how much

the other person’s response affects the shift.

Memory conformity is greatest when the lines in

Figure 3 are furthest apart and is least when the

lines are closest. The distance between the highest

and lowest lines is greatest, for both fillers (1.55)

and targets (1.40), when the initial response was

uncertain, the 0-point. For fillers, when the initial

response was confident and accurate the shift was

only 0.41, compared with a shift of 0.98 when the

participant confidently, but inaccurately, reported

that they did see the item. For targets, when the

initial response was confident, but inaccurate, the

shift was 0.88. When the initial response for

targets was confident and accurate the shift was

only 0.10.The statistically significant three-way interac-

tion, x2(2)�57.98, p B.001, for Experiment 2 is

shown in Figure 4. Again the shifts were largest

when the initial responses were uncertain. The

predicted shifts between extreme responses for

the other person were for fillers, 1.50, and for

–1.0

–3 –2 –1 0 1 2 3

–0.5

0.0

0.5

1.0Fillers

Initial response

–3 –2 –1 0 1 2 3

Initial response

Pre

dict

ed s

hift

Other says target

Othersays filler

–1.0

–0.5

0.0

0.5

1.0Targets

Pre

dict

ed s

hift

Other saystarget

Othersays filler

Figure 3. The memory conformity effect, as measured by the shift from belief before finding out the other person’s response to

belief after finding out the other person’s response, for different levels of initial memory confidence for Experiment 1. The left panel

is for fillers. The right panel is for targets. The light-grey lines are when the other person says the item is a target with confidence; the

black lines are when the other person says the item is a filler with confidence. Intermediate lines are for the intermediate levels of

confidence.

–1.0

–0.5

0.0

0.5

1.0

Fillers

Pre

dict

ed s

hift

Other says target

Othersays filler

–1.0

–0.5

0.0

0.5

1.0

Targets

Pre

dict

ed s

hift

Other saystarget

Othersays filler

–3 –2 –1 0 1 2 3

Initial response

–3 –2 –1 0 1 2 3

Initial response

Figure 4. The memory conformity effect, as measured by the shift from belief before finding out the other person’s response to

belief after finding out the other person’s response, for different levels of initial memory confidence for Experiment 2. The left panel

is for fillers. The right panel is for targets. The light-grey lines are when the other person says the item is a target with confidence; the

black lines are when the other person says the item is a filler with confidence. Intermediate lines are for the intermediate levels of

confidence.

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targets, 1.40. For fillers, when the initial responsewas confident and accurate the predicted shift was0.56. The shift was 1.10 when the confidentresponse for a filler was inaccurate. The corre-sponding shifts for targets were 0.72 and 0.22.Thus, after controlling for initial confidence, thetwo experiments yield very similar patterns ofresults: confident accurate memories are distortedless than confident inaccurate memories.

DISCUSSION

When two people discuss an event, what oneperson says can affect what another person laterreports. Whether memory conformity occurs de-pends on several factors. Here it is shown thatpeople are most likely to be influenced when theirown initial memory is weak. This was shown bothby larger memory conformity effects when en-coding was worse in Experiment 2 than inExperiment 1, and by uncertain responses inboth experiments being the most malleable. Im-portantly, this relationship depended on whetherthe initial memory was accurate or inaccurate.Controlling for level of initial self-reported mem-ory confidence, inaccurate memories were moremalleable than accurate memories. Thus, even ifsomebody reported with high confidence that anobject was previously shown, if the memory wasin error it was more easily distorted than if thememory was correct. Similarly, if someone waspositive that a drawing was not previously shown,this memory was more easily changed if thememory was inaccurate than if it was accurate.This is an important finding for both applicationsand theories of memory distortion.

With respect to applications, consider, forexample, that many crimes are witnessed byseveral people and these people usually talkabout the crime before police can interviewthem (Paterson & Kemp, 2006; Skagerberg &Wright, 2008b). Finding that accurate memoriesare less susceptible to memory conformity thaninaccurate memories, even after controlling forself-reported initial memory confidence, is goodnews. It means errant witnesses are more likely tobe corrected, than accurate witnesses are to bemisled. However, in the current experiments bothinitially accurate and inaccurate memories weredistorted, so it is important not to conclude thataccurate memories are immune to memory con-formity. Further, the brief time lapse ofthe current studies means that false recollective

experiences*what Brainerd, Wright, Reyna, andMojardin (2001) call phantom recollections*would be unlikely to materialise.

The three-way interactions depicted in Figures3 and 4 show that the memory conformity effect isdifferent for accurate and inaccurate memories.This means that a simple straw-man proposaldepicted in Figure 1, which only uses strength ofmemory, does not account for the data and can berejected. It is clear that there is some character-istic about the memory, beyond what is beingmeasured by participants’ ratings of memorystrength, that affects the degree to which thememory can be distorted.

One explanation for this is that there aretwo types of memories*recollective and non-recollective*and that recollective experiences aremore likely to be associated with accurate mem-ories than with inaccurate memories. Becauserecollective memories are less malleable thannon-recollective memories, this would accountfor accurate memories being less malleable.Further, because the probability of a recollectiveexperience is greater for accurate positive recol-lections than for diagnostic recall-to-reject experi-ences (Gallo, 2004), this would account formemory conformity being least when peopleaccurately remember an item with certainty. It isworth stressing, however, that other theoriescould account for this. The main empirical findingcan be recast in a more theory-neutral manner:the confidence scale does not adequately capturesome aspect of the memory that is associated withhow easily the memory is distorted.

Much of the memory distortion research hasfocused on how information presented after anevent can create memory errors. It is importantfor applied and theoretical purposes to examinememory distortion for both accurate and inaccu-rate memories. When two people discuss an eventthey have both experienced, research shows thathearing somebody else correctly report informa-tion increases the chance that others are accurate,and that hearing somebody else incorrectly reportinformation decreases the chance that othersare accurate. Because what people free reportabout an event tends to be accurate (Koriat &Goldsmith, 1996), this would mean that even ifthe effect of memory conformity was the same foraccurate and inaccurate information, memoryconformity would tend to increase accuracy inmost situations. The current research shows thatthe positive effects of memory conformity should,on average, be even greater for two reasons. First,

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because people are likely to be more confidentwhen they are accurate, finding that uncertainresponses are the most malleable means thatthe most erroneous items are most likely to bechanged. Second, and the main finding from theseexperiments, even controlling for expressed con-fidence, inaccurate beliefs are more likely to bechanged. The theoretical importance of this find-ing is that it shows that there is something beyondthe measures of confidence used that relates tomemory malleability. One explanation is thatsome highly confident memories have associatedrecollective experiences, and these memories aremore stable than equally confident memorieswhich do not have associated recollective experi-ences.

Manuscript received 14 February 2011

Manuscript accepted 30 December 2011

First published online 24 February 2012

REFERENCES

Baayen, R. H., Davidson, D. J., & Bates, D. M. (2008).Mixed-effects modeling with crossed random effectsfor subjects and items. Journal of Memory andLanguage, 59, 390�412.

Baron, R. S., Vandello, J. A., & Brunsman, B. (1996).The forgotten variable in conformity research:Impact of task importance on social influence.Journal of Personality and Social Psychology, 71,915�927.

Bates, D., & Maechler, M. (2010). lme4: Linear mixed-effects models using S4 classes. R package version0.999375-42. Retrieved from http://CRAN.R-project.org/package�lme4.

Blank, H. (2009). Remembering: A theoretical inter-face between memory and social psychology. SocialPsychology, 40, 164�175.

Brainerd, C. J., & Reyna, V. F. (2005). The science of falsememory. New York, NY: Oxford University Press.

Brainerd, C. J., Wright, R., Reyna, V. F., &Mojardin, A. H. (2001). Conjoint recognition andphantom recollection. Journal of Experimental Psy-chology: Learning, Memory, and Cognition, 27,307�327.

Bramao, I., Reis, A., Petersson, K. M., & Faısca, L.(2011). The role of colour information on objectrecognition: A review and meta-analysis. ActaPsycholica, 138, 244�253.

Carlucci, M. E., Kieckhaefer, J. M., Schwartz, S. L.,Villalba, D. K., & Wright, D. B. (2011). The SouthBeach study: Bystanders’ memories are more malle-able. Applied Cognitive Psychology, 25, 562�566.

Deutsch, M., & Gerard, H. B. (1955). A study ofnormative and informational social influence uponindividual judgment. Journal of Abnormal andSocial Psychology, 51, 629�636.

Field, A. P. (2009). Discovering statistics using SPSS(3rd ed.). London: Sage Publications.

Fishbein, M., & Ajzen, I. (1975). Beliefs, attitudes,intentions and behavior. Reading: MA: Addison-Wesley.

Gabbert, F., Memon, A., & Wright, D. B. (2007). I sawit for longer than you: The relationship betweenperceived encoding duration and memory confor-mity. Acta Psychologica, 124, 319�331.

Gallo, D. A. (2004). Using recall to reduce falserecognition: Diagnostic and disqualifying monitor-ing. Journal of Experimental Psychology: Learning,Memory, and Cognition, 30, 120�128.

Goldstein, H. (2003). Multilevel statistical methods (3rded.). London, UK: Edward Arnold.

Harris, C. B., Paterson, H. M., & Kemp, R. I. (2008).Collaborative recall and collective memory: whathappens when we remember together? Memory, 16,213�230.

Hox, J. (2010). Multilevel analysis: Techniques andapplications (2nd ed.). New York, NY: Routledge.

Koriat, A., & Goldsmith, M. (1996). Monitoring andcontrol processes in the strategic regulation ofmemory accuracy. Psychological Review, 103, 490�517.

Merckelbach, H., Van Roermund, H., & Candel, I.(2007). Effects of collaborative recall: Denying trueinformation is as powerful as suggesting misinfor-mation. Psychology, Crime & Law, 13, 573�581.

Nova Development. (2004). Art explosion:800,000 premium quality graphics [CD Rom].Calabasas, CA: Author.

Paterson, H. M., & Kemp, R. I. (2006). Co-witnessestalk: A survey of eyewitness discussion. Psychology,Crime, Law, 12, 181�191.

Rajaram, S., & Pereira-Pasarin, L. P. (2010). Collabora-tive memory: Cognitive research and theory. Per-spectives on Psychological Science, 5, 649�663.

Roediger, H. L. (2010). Reflections on intersectionsbetween cognitive and social psychology: A perso-nal exploration. European Journal of Social Psy-chology, 40, 189�205.

Roediger, H. L, Meade, M. L., & Bergman, E. T.(2001). Social contagion of memory. PsychonomicBulletin & Review, 8, 365�371.

Ruppert, D., Wand, M. P., & Carroll, R. J. (2003).Semiparametric regression. New York, NY: Cam-bridge University Press.

Schneider, D. M. (1996). Effect of social context onrecognition memory (MA thesis). Rice University,TX, USA.

Schneider, D. M., & Watkins, M. J. (1996). Responseconformity in recognition testing. PsychonomicBulletin & Review, 3, 481�485.

Skagerberg, E. M., & Wright, D. B. (2008a). The co-witness misinformation effect: Memory blends ormemory compliance? Memory, 16, 436�442.

Skagerberg, E. M., & Wright, D. B. (2008b). Theprevalence of co-witnesses and co-witness discus-sions in real eyewitnesses. Psychology, Crime, Law,14, 513�521.

Sutton, J., Harris, C., Keil, P., & Barnier, A. (2010). Thepsychology of memory, extended cognition, and

ACCURACY AND MEMORY CONFORMITY 263

Dow

nloa

ded

by [

Tex

as A

& M

Int

erna

tiona

l Uni

vers

ity]

at 0

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socially distributed remembering. Phenomenologyand the Cognitive Sciences, 9, 521�560.

Wright, D. B. (1998). Modelling clustered data inautobiographical memory research: The multilevelapproach. Applied Cognitive Psychology, 12, 339�357.

Wright, D. B., & Carlucci, M. E. (2011). The responseorder effect: People believe the first person whoremembers an event. Psychonomic Bulletin &Review, 18, 805�812.

Wright, D. B., Horry, R., & Skagerberg, E. M. (2009).Functions for traditional and multilevel approachesto signal detection theory. Behavior Research Meth-ods, 41, 257�267.

Wright, D. B., & London, K. (2009). Multilevel model-ling: Beyond the basic applications. British Journalof Mathematical and Statistical Psychology, 62, 439�456.

Wright, D. B., London, K., & Waechter, M. (2010).Social anxiety moderates memory conformity inadolescents. Applied Cognitive Psychology, 24,1034�1045.

Wright, D. B., Mathews, S. A., & Skagerberg, E. M.(2005). Social recognition memory: The effect ofother people’s responses for previously seen andunseen items. Journal of Experimental Psychology:Applied, 11, 200�209.

Wright, D. B., Memon, A., Skagerberg, E. M., &Gabbert, F. (2009). When eyewitnesses talk. CurrentDirections in Psychological Science, 18, 174�178.

Wright, D. B., Self, G., & Justice, C. (2000). Memoryconformity: Exploring misinformation effects whenpresented by another person. British Journal ofPsychology, 91, 189�202.

Yonelinas, A. P. (2002). The nature of recollection andfamiliarity: A review of 30 years of research. Journalof Memory and Language, 46, 441�517.

APPENDIX

The social recognition test procedure used herebuilds on the important work of Schneider andWatkins (1996), which was based on Schneider’s(1996) master thesis. She provides the data for herstudies in her thesis. We will use the data from hersecond study to illustrate the statistical methodused to analyse social recognition test proceduredata (Wright, Horry, & Skagerberg, 2009). This isa relatively new procedure and is still not widelyknown. The method is called multilevel (ormixed) modelling. More details can be found inGoldstein (2003) for statistical treatment; in Hox(2010) for a textbook aimed at social sciencegraduate students; in Field (2009) for an intro-ductory chapter for psychologists; and in Wright(1998) for arguments for using multilevel model-ling with memory research.

The main difference between the multileveland the traditional approach is that instead of

predicting each participant’s proportion accurate(or the mean value or the d’ score from signaldetection theory or any other single statistic) ineach cell, as is done with the traditional approach,the multilevel analyst predicts how the participantresponds for each test trial. To estimate multilevelmodels in most software packages it is necessaryto have each line of data corresponding to atest trial. Most statistics packages have functionsto restructure the data to this format. ThusSchneider’s data (1996, in her Appendix B) couldhave the following form:

Participant Target Confederate Response

1 0 2 21 0 4 31 1 6 61 1 2 3: : : :

where Target�0 means the item was filler andTarget�1 means the item was a target. This is along thin data file. There were 96 trials for eachof 24 participants. There were 10 missing trials(B 1%), thus the total number of lines in the datamatrix is 2294.

The statistical procedure is like a normalregression, predicting the participant’s responsefrom the confederate’s response and whetherthe item is a filler or a target. If each participanthad only a single trial, the model could be writtenas:

Responsei ¼ b0 þ b1 Targeti þ b2 Confederatei þ ei

and the computer would find the values of the bsthat minimise

Pe2

i (i.e., ordinary least squares).The estimate for b1 measures memory (howmuch more confident people are for targets thanfor fillers) and b2 measures the influence of theconfederate. This statistical method producesseparate estimates for memory and memoryconformity. The interaction of these can beexamined to explore if memory conformity isdifferent for targets and fillers. Other variablescan be added as with other multiple regressions.Interactions of these variables with Target andConfederate test if these other variables moderatememory and memory conformity, respectively.

The traditional approach is not appropriatehere because each participant had 96 test trials.All the i subscripts are replaced with ij to denotethe ith trial for the jth participant. It is likely that

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the individuals will have different intercepts. Thiscould be incorporated into the model by changingthe intercept term from b0 to b0�uj. The uj

allows variation around the intercept for theparticipants and it is usually assumed to benormally distributed. Other random variablescan be added. For example, to take into accountdifferences in stimuli (some words/pictures maylook more familiar than others) a random vari-able for stimulus variability can be included. Thismakes the model a cross-classified model and iswhat is done in our analyses. Computationaldetails can be found in Baayen et al. (2008).The analyst might also want to allow the partici-pants and/or the stimuli to vary in accuracy, whichcan be done by allowing b1 to vary. The simplestmultilevel model has just a single random vari-able, uj:

Responseij ¼ b0 þ b1ij Targetij þ b2 Confedrateij þ uj

þ eij

This model is complex enough for illustrativepurposes (see Wright & London, 2009, for furtherextensions).

The purpose of Schneider’s (1996) secondstudy was to test if the confidence of theconfederate’s response affected the participant’sresponse. This can be examined in a few ways.If we recode the confederate’s response as athree-category variable, ‘‘new’’, ‘‘old’’, or control,this model can be tested. This takes into accountwhether the confederate said ‘‘new’’ or ‘‘old’’,but not how much confidence they expressed. We

used the R package lme4 (Bates & Maechler,

2010; all the main statistical packages can now

estimate these models) to fit this model and it

produced a x2 deviance of 7850. It showed that

higher confidence was given to targets than to

fillers (i.e., memory was shown) and that higher

confidence was given if the confederate said the

item was a target than if the confederate said it

was a filler (and the control group was in

between). A variable for the confederate’s con-

fidence on the �3 to �3 (with 0 for control group)

scale was added to the model. The question is

whether taking into account the magnitude of the

confederate’s response improved the fit of

the model beyond just having the categorical

variable. It did. The new x2 deviance is 7838,

which is a statistically significant improvement,

x2(1)�12.26, p B.001. This shows that the

confidence of the confederate affected the parti-

cipant’s response beyond just whether the con-

federate said ‘‘new’’ or ‘‘old’’.More complex models can be used, but this

basic multilevel model allows the analyst to

measure memory and memory conformity. The

interactions between them and any interactions

with any moderator variables can be included by

adding a new variable to the model that is the

product of the variables which are part of the

interaction. The multilevel model is more flexible

and more powerful than traditional methods, and

should be used when analysing data collected

using the social recognition test.

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