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The power of extraversion? Reduced false memories for positive events
Personality and Individual Differences 159 (2020) 109861
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Personality and Individual Differences journal homepage: www.elsevier.com/locate/paid
The power of extraversion? Reduced false memories for positive events a,⁎
a
b
Chiara Mirandola , Enrico Toffalini , Emilia Ferruzza , Francesca Pazzaglia a b
T
a
Department of General Psychology, University of Padova, via Venezia 8, Padova 35131, Italy Department of Developmental and Social Psychology, University of Padova, via Venezia 8, Padova 35131, Italy
A R T I C LE I N FO
A B S T R A C T
Keywords: Extraversion Personality traits Emotion False memories
Evidence on the relation between personality traits and false memories is scarce and partly contradictory. For example, extraverts have been found to be less suggestible to induced memory distortion (through the misinformation paradigm); however, they tend to produce a higher amount of spontaneous false memories (through the Deese-Roediger-McDermott paradigm). Whether Extraversion influences false memories for positive and negative events is unclear. The current study was aimed at clarifying the effects of Extraversion (Eysenck Personality Questionnaire) on false memories using an ecological paradigm for emotional events. Participants were 151 volunteering undergraduate students. Results showed that Extraversion predicted reduced false memories for positive events, compared to negative ones. No effects of Neuroticism and Psychoticism were found. Results are discussed in terms of the stable characteristics of the rememberer that may affect memory distortions.
1. Introduction That memory is a re-constructive process and may lead people to distortions is a matter of fact. A deluge of studies have revealed the primary role of emotion in influencing subsequent true and false memory. Specifically, there is evidence in favor of both enhanced (Porter, Taylor & Ten Brinke, 2008) and reduced (Mirandola, Toffalini, Ciriello & Cornoldi, 2017, 2014; Storbeck, 2013) false memories for emotional events. Also the transient mood states of the rememberer affect false memories. Positive moods typically lead to more false memories than negative moods (Storbeck & Clore, 2005), but this may depend more on arousal than valence per se (Mirandola & Toffalini, 2016; see Bookbinder & Brainerd, 2017 for a comprehensive review). Surprisingly, the stable characteristics of the rememberer, such as personality traits, have not received much attention. Some studies have focused on how general personality traits may influence susceptibility to memory distortions. For example, Porter, Birt, Yuille and Lehman (2000) investigated whether personality would correlate to susceptibility to recall false implanted childhood events after repeated interviews. The authors found that susceptibility to memory distortion was related to higher extraversion scores in the interviewer and lower extraversion scores in the participants. Extraverted interviewers may be more persuasive and successful in planting false memories in introverted individuals, who may be more compliant and thus more
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susceptible to believe to have experienced false events. On a similar venue, more suggestible participants (tested with the Gudjonsson Suggestibility Scale (GSS-2; Gudjonsson, 1997) recalled fewer detail of the original event (Liebman et al., 2001). Notably, the personality traits of extraversion and conscientiousness were associated with suggestibility on the GSS-2. A large study investigated the association between many personality traits and susceptibility to misinformation (Zhu et al., 2010). In this study personality was assessed with the Temperament and Character Inventory – Revised (Cloninger, 1999). The authors hypothesized a negative correlation between novelty seeking and false memory, based on previous evidence with extraversion – see Porter et al. (2000). Results showed that novelty seeking was indeed negatively correlated to overall false memory; however, this result was not confirmed when two extreme groups were created. Furthermore, individuals with high scores in cooperativeness, reward dependence and self-directedness, combined with low cognitive abilities, were most subject to misinformation. The authors are cautious in explaining the first result, and thus why do novelty seekers recall fewer false events remain somewhat unexplained. Novelty seekers share some characteristics with extraverts, including the need to find stimulation, the tendency to be enthusiastic and to explore the environment. Extraverts’ susceptibility to postevent information was found to be lower than that of introverts (Ward & Loftus, 1985). The explanation of this effect was rooted in extraverts’
Corresponding author. E-mail addresses: [email protected] (C. Mirandola), enrico.toff[email protected] (E. Toffalini).
https://doi.org/10.1016/j.paid.2020.109861 Received 17 January 2020; Accepted 22 January 2020 0191-8869/ © 2020 Elsevier Ltd. All rights reserved.
Personality and Individual Differences 159 (2020) 109861
C. Mirandola, et al.
photographs: 14 photographs depicted the most typical events of the episode (i.e., for the waking up episode, examples are getting dressed, having breakfast) and seven photographs depicted cause-effect scenes. Specifically, 1 photograph depicted the causal event (e.g., for the dating script, a girl approaching a boy waiting for her on a bench) and 6 photographs its outcome: two photographs depicted a neutral outcome (the girl and the boy are friends and meet for exchanging a book), 2 photographs a negative outcome (the boy being aggressive toward the girl for being late) and 2 photographs a positive outcome (the boy and the girl are kissing each other). Target-distractor photographs were counterbalanced across participants.
lower cortical arousal compared to introverts. Indeed Eysenck postulated that extravert people need to seek for outside stimulation given that their internal level of arousal is reduced; conversely, introvert's higher cortical arousal would lead them to seek for quiet and reliable situations and contexts (Eysenck, 1967). Given that high arousal may interfere with memory retention, it results that introverts are more prone to accept misleading information. However, in a study using a paradigm which elicits spontaneous false memories (Deese-Roediger-McDermott Paradigm; Roediger & McDermott, 1995), extraverts falsely recalled a substantially higher number of critical lures than introverts (Sanford & Fisk, 2009). This finding might be interpreted as a direct consequence of enhanced semantic priming effect, already evident in these individuals (Matthews & Harley, 1993). Extraverts’ predisposition induces a significant raise in the activation of the critical lure till it is recognized as a previously presented word. On the contrary, introverts were found to be less sensitive to memory distortions due to their restricted attentional focus, which reduces the spreading of activation. The extant literature is mixed, depending on the type of paradigm used. Furthermore, the specific relation between Extraversion and valence of to be-remembered events has been neglected. In terms of memory accuracy, extravert individuals reported a higher amount of happy than negative memories (Mayo, 1989). Furthermore, extravert individuals recollect more positive autobiographical memories whereas neurotic individuals recollect more negative ones (Denkova, Dolcos & Dolcos, 2012). Based on this evidence, in the current study we aimed at analysing whether individual scoring high in Extraversion – measured through the Eysenck Personality Questionnaire – would be less prone to false memories for positive events compared to negative or neutral ones, employing an ecological false memory task which induces spontaneous false memories for events. Investigating the relation between emotional memory and the two other facets of the Eysenck Personality Questionnaire – namely Neuroticism and Psychoticism – is more exploratory. Based on the literature on anxiety (Toffalini, Mirandola, Coli & Cornoldi, 2015; Toffalini, Mirandola, Drabik, Melinder & Cornoldi, 2014), we reasoned that people scoring high on Neuroticism would show higher production of negative false memories compared to positive ones. Furthermore, some studies showed the influence of Psychopathy (which is similar to Psychoticism) and Narcissism on memory. These personality traits are included in the “dark triad” model of personality and we preliminary conducted exploratory analyses to test whether there was any relation between the dark triad traits and false memories. We reported the relevant results in the Supplemental material.
2.2.2. EPQ-R questionnaire The Eysenck Personality Questionnaire – Revised (Eysenck, 1991) is a revised form of the traditional personality questionnaire assessing Extroversion, Neuroticism and Psychoticism. The Italian reduced version was administered which includes 48 items, 12 for each of the subscales (Dazzi, Pedrabissi & Santinello, 2004). Participants are required to choose between two yes/no questions for each item. Examples of items are the following: Extraversion: “Do you enjoy meeting new people?”; Neuroticism:“Are you a worrier?”; Psychoticism: “Do you prefer to go your own way rather than act by the rules?” 2.2.3. Control measures We administered the Questionnaire for the assessment of psychopathology in adolescence (QPAD; Sica, Chiri, Favilli & Marchetti, 2011) which is a broad-spectrum questionnaire designed to evaluate the presence of psychopathological symptoms. It is formed by 25 statements; responses are given on a 4 – point Likert scale ranging from 1 (false) to 4 (true) for each item. Only the depression and the anxiety subscales were measured, given their importance for the emotional memory domain (Toffalini et al., 2014, 2015). The depression and anxiety scores were treated as control variables in the subsequent analyses. We administered the forward and the backward digit span tasks (Wechsler, 2008). Participants are presented with sequences of digits of increasing length and difficulty. In the forward digit span task, individuals are required to repeat digits in the same order in which they were presented; in the backward digit span task, individuals are required to repeat digits in the opposite order in which they were presented. 2.3. Procedure All participants were tested individually at the Department of [BLINDED], University of [BLINDED]. Upon arrival, participants were initially administered the False memory task for emotional events.
2. Methods 2.1. Participants
2.3.1. Encoding phase Participants were instructed that they would see a series of photographs depicting people performing various everyday activities and that they would have to pay close attention to the stories. Each photo was shown for 2 s and was followed by a 2‑sec‑long black screen. The order of presentation of the 9 episodes was fixed, whereas target-distractor photographs and outcome's valence of each script were balanced across participants. The encoding phase was followed by a 15-min retention interval. During this interval, participants were administered the digit span tasks and the Q-PAD questionnaire.
A group of 151 undergraduate students from the University of [BLINDED] (Mean age = 22.5 years, SD = 2.2, Females = 129) participated in this study and received extra course credits. Written informed consent was obtained by all students prior to participation. The study was approved by the local ethical committee of the University of [BLINDED]. 2.2. Materials 2.2.1. False memory task for emotional events We tested emotional false memories with a paradigm including a series of photographs organized in nine episodes, depicting varying situations, such as waking up, going shopping, dating/meeting a friend, going to a birthday party, mountain climbing, playing at the slot machine, coming back from a journey, participating to a track competition and going on a bike trip (see Mirandola, Toffalini, Ciriello & Cornoldi, 2017 for an example). Each episode was comprised of 21 color
2.3.2. Recognition phase After the retention interval, participants received a surprise memory test. Stimuli for the recognition phase consisted of a set of 45 target and 45 distractor photographs presented in a randomised order. For each episode, four targets and four distractors were included. One of the four distractor photographs depicted the causal antecedent whose matching outcome had been presented at the encoding phase. Finally, 18 2
Personality and Individual Differences 159 (2020) 109861
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model selection of alternative models. For parsimony and to avoid overly complex models, no interactions between more than two variables at a time were tested. Because a binomial variable was modelled, effect sizes were expressed by reporting estimated probabilities or odds ratios (OR). The latter were calculated as the exponential values of the model coefficients. As we rescaled all quantitative predictors to standardized normal distributions before the analyses, ORs represent the change in odds of a “yes” response (whether the dependent variable is causal errors, gap-filling error, or hit) for every increase of 1 SD of the predictor. ORs or estimated probabilities were reported only for effects that were found relevant using the model selection criteria described above.
Table 1 Mean proportion (and standard deviations) of causal errors, gap-filling errors, and hits. Valence Causal errors Gap-filling errors Hits Sensitivity index (d’)
Neutral .45 (0.34) .28 (0.23) .81 (0.14) 1.80 (1.08)
Negative .43 (0.33) .26 (0.22) .79 (0.17) 1.79 (1.09)
Positive .42 (0.32) .26 (0.21) .81 (0.16) 1.88 (1.08)
photographs inconsistent with any of the scripts were included (9 targets and 9 distractors). The memory test consisted of a self-paced yes/ no recognition task. In the case of a “yes” response participants were further asked to specify if they “remembered” or “knew” the photograph shown. Participants had to select the “remember” option when they could clearly remember the photo and could retrieve some qualitative details related to it. Conversely, they had to select the “know” option when they were familiar with it, but they could not retrieve any specific detail associated with it. At the end of the recognition phase, participants filled the personality questionnaires. Participants were then debriefed about the aims of the study. The entire experimental session lasted approximately one hour and a half.
3.1. Valence and control variables As a first step, we assessed the effects of Valence and the control variables to select a baseline model before testing the effects of the personality factors. The starting model was the one with the intercept alone. Subsequently, Valence was added, followed by the control variables and their interaction with Valence. Eventually, the model with the lowest AIC was kept as the baseline model for the subsequent phase in which the role of the personality factors was assessed. With regard to the fixed effect of Valence on causal errors, a significant main effect was not found, ΔAIC = +3.00, χ2(2) = 1.06, p = .59. The probability of producing causal errors is similar in the three emotional conditions and is reported in Fig. 1. The expected reduction of emotional false memories compared to neutral ones was found when we analysed the Remember responses associated to causal errors. In this case Valence reduce the AIC of the model and it had a significant main effect on Remember responses associated to causal errors, ΔAIC = −2.1, χ2(2) = 6.03, p = .049 (see Fig. 2). Compared to the neutral condition (i.e., the reference), errors in both the negative, OR = 0.76, 95% CI (0.52, 1.11), and positive conditions, OR = 0.62, 95% CI (0.42, 0.91), were less likely. As can be seen in Fig. 2, Remember responses are produced to a lower extent for both negative and positive false memories compared to neutral ones. Conversely, as expected, no main effect of Valence was found for Know responses associated to causal errors, ΔAIC = +3.2, χ2(2) = 0.80, p = .67. Nonetheless, all analyses presented subsequently were conducted on the overall causal errors, for consistency with previous reports. However, we ensured that the same conclusion were also valid for causal errors associated with Remember responses. Among the control variables, only the Q-PAD anxiety contributed to increase the model fit when entered as a main effect in addition to Valence, ΔAIC = −11.3, χ2(1) = 13.34, p < .001. Model coefficients showed that it had an overall positive effect on false memory, OR = 1.42, 95% CI (1.18, 1.73), such that higher anxiety was associated with a higher false memory rate.
3. Results We reported the mean proportions of causal errors, gap-filling errors, and hits for each valence condition for descriptive purposes (Table 1). As a preliminary step, we calculated the sensitivity d’ scores for each participant, divided by valence condition. In each condition, d’ was calculated as z (hit rate) – z (gap filling error rate); for rates equal to 1.00 or 0.00, we subtracted or added 0.01, respectively, to keep the d’ within the finite range. Causal errors were not included in this phase as they represent a specific kind of memory error which was treated separately. As can be seen in Table 1, d’ was rather high on average (around 1.80) and there was negligible variation across the three conditions. A mixed-effects linear model with valence condition as the fixed effect of interest, d’ as the dependent variable, and participants as random effects, suggested negligible effect of valence condition on d’ (likelihood-ratio test against a model without valence as the fixed effect was used): χ2(2) = 1.10, p = .58. As the data consisted of repeated measures of binomial type (“yes”: 1, or “no”: 0), data analysis was conducted using logistic mixed-effects models (Baayen, 2008; Jaeger, 2008). Causal errors were the “yes” responses to causal distractors. The fixed effects of interest were Valence (3 levels: neutral, negative, positive; the baseline was “neutral”), control variables (forward and backward digit span, and anxiety and depression scores of the Q-PAD), and the personality factors. Participants were treated as random effects. Model comparison was adopted to assess the relevance of the effects of interest. Model selection was based on the Akaike Information Criterion (Akaike, 1998; Burnham, Anderson & Lower, 2002). AIC indicates better fitting model, and it can be used both for nested models and models with alternative predictors. To give an idea of the amount of evidence provided, we adopted the rule of thumb proposed by Raftery (1995) with reference to the Bayes Factor (another type of evidence ratio). Following those guidelines, we suggest to interpret ΔAIC = −2.0 as positive evidence for an effect, and ΔAIC = −6.0 as strong evidence for an effect. Conversely, ΔAIC = +2.0 and ΔAIC = +6.0 were interpreted respectively as positive and strong evidence against an effect. Any |ΔAIC| < 2.0 (in absolute terms) suggests uncertainty in making a decision. For the effects of interest statistical significance was also assessed with likelihood ratio tests for nested models, based on the chi-square distribution (Pinheiro & Bates, 2000). Note that likelihood ratio test here can be used only for nested models, and thus it cannot serve for
Fig. 1. Emotional false memories. Estimated probability of causal errors as a function of valence. 3
Personality and Individual Differences 159 (2020) 109861
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3.3. Accuracy The final model obtained on causal errors was fitted, in an additional analysis, also on the “hit” responses (i.e., on accuracy). However, none of the effects included in it adequately fitted accuracy. For the interaction between Extraversion and Valence, ΔAIC = + 2.7, χ2(2) = 1.33, p = .51 (for the main effect of Valence, ΔAIC = + 2.9, χ2(2) = 1.10, p = .58). For the control variable Q-PAD anxiety, ΔAIC = + 1.7, χ2(1) = 0.30, p = .59. The same was true for accuracy measured as d’ (see at the beginning of the Results section). 4. Discussion The stable characteristics of the rememberer – such as personality traits – have been neglected in the extant literature investigating the relation between emotional experiences and the tendency to incur spontaneous false memories. Specifically, evidence on Extraversion is contradictory, with studies showing extraverts’ diminished suggestibility to memory distortions - when misinformation paradigms are employed (Porter et al., 2000; Ward & Loftus, 1985) - and enhanced production of errors when associative memory paradigms that elicit spontaneous false memories are instead used (Sanford & Fisk, 2009). Spontaneous false memories have been studied employing the DRM (Deese-Roediger-McDermott) paradigm, which consists on the presentation of semantically related wordlists. Within each list, not only are words semantically related to each other (e.g., tired, pillow, bed) but they also converge in meaning to a nonpresented critical lure (e.g., sleep); recall or recognition of the critical lure at test represents a false memory. The fact that extravert people recall to a higher extent than introverts such critical lures, seems to be related to the semantic priming effect – boosted in extraverted. Indeed, this would make them falsely accept more critical lures into their memory.The current study was aimed at clarifying the effect of Extraversion on emotional false memories, using a false memory task that elicits spontaneous inferential false memories but it is indeed more ecological than wordslists. The main result was that Extraversion interacted with valence, such that higher scores in Extraversion predicted diminished false memories for positive compared to negative episodes. There is evidence that extraverts tend to manifest an attentional bias toward positive stimuli (Derryberry & Reed, 1994), which might suggest an enhanced elaboration of positive detail; this might in turn enhance memory accuracy for positively valenced events. Indeed, individuals with high levels of extraversion may focus their attention toward positive episodes, or rather they may encounter more difficulties disengaging from positive stimuli which are motivationally relevant to them, like it has been suggested (Denkova et al., 2012). In both cases, whether their attentional focus is biased toward positive stimuli or they are less able to disengage attention from positive ones, it results in extraverts’ diminished propensity to produce false memories. Indeed, encoding positive episodes under enhanced attentional focus results in subsequent reduced memory impairment at retrieval. This is confirmed also by the result on subjective recollection: extraverts do not only produce a lower amount of positive false memories but they also associate fewer Remember responses to them; thus, once false memories for positive events occur, they are not characterized by vivid remembering. A lower amount of Remember responses associated to emotional episodes (both negative and positive) compared to neutral ones is evinced also in the overall sample, regardless of individual differences in personality traits, extending to subjective recollection what was previously found on overall false memories (Mirandola et al., 2017). Nonetheless, we did not find a similar interaction between extraversion and valence on memory accuracy (i.e., hits, or true recognitions); it must be noted that the False memory task used in this study is specifically developed for eliciting inferential false memories; performance on memory accuracy is typically high and valence – or its interaction with individual differences - does not seem to influence true recognition (see
Fig. 2. Subjective recollection and false memories. Estimated probability of causal errors associated with Remember responses as a function of valence.
Any alternative model, including any other main effect or interaction with Valence, had a clearly worse fit than the best model, with all ΔAICs > +3.6.
3.2. EPQ-R personality factors and false memories As in the previous phase, we fit all models including the EPQ-R personality traits (i.e., Extraversion, Neuroticism, Psychoticism) and their combination. Factors were not taken into consideration for more complex models if they worsened the fit. Up to two-way interactions with Valence were also considered. The best fitting model added a two-way interaction between Valence and Extraversion, and a main effect of Neuroticism, to the baseline model, ΔAIC = −6.9. Compared to this model, the second best one included also Psychoticism, but it had a rather worse fit, ΔAIC = +1.7. All other alternative models had clearly worse fit, all ΔAICs > +2.9. With regard to the best model, the two-way interaction between Valence and Extraversion reached statistical significance when compared against the nested model that included only the main effects, ΔAIC = −4.1, χ2(2) = 8.11, p = .02 (see it detailed below). Unsurprisingly, also the main effect of Neuroticism was significant, ΔAIC = −2.9, χ2(1) = 4.92, p = .03. Looking at the model parameters suggested that Neuroticism had a negative effect on false memory, OR = 0.77, 95% CI (0.61, 0.97). This seems at odds with the fact that a conceptually related measure such as Q-PAD anxiety had an enhancing effect on false memory, casting a doubt that this effect of Neuroticism may be due to a near-overfitting effect linked to the fact that Q-PAD anxiety and Neuroticism indeed correlate strongly, r = 0.61. This suspicion is strengthened by the fact that, if Q-PAD anxiety was not controlled for in the model, then Neuroticism had not effect on false memory and it would even worsen the model fit, ΔAIC = +2.0, χ2(1) = 0.03, p = .87. For all these reasons, we eventually chose to exclude Neuroticism from the final model. Therefore, the latter had the following predictors: Q-PAD anxiety (as a control variable), and Valence in interaction with Extraversion. With regard to the two-way interaction between Extraversion and valence, it is depicted in Fig. 3. As compared to the neutral condition, the contrast for the negative condition was OR = 1.28, 95% CI (0.96, 1.71), for the positive condition it was OR = 0.84, 95% CI (0.62, 1.13). Both visual inspection of Fig. 3 and the consideration of the model parameters suggested that the clearest contrast within the model indicated a diverging effect of Extraversion on negative vs positive false memory, OR = 1.52, 95% CI (1.14, 2.03). It should be noted that when only causal errors associated with Remember responses were considered, the same final model was obtained, and with similar effects. 4
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Fig. 3. Personality and false memories. Estimated probability of causal errors as a function of Extraversion and Valence.
Mirandola et al., 2014, 2017). To conclude, the current study brought evidence in favor of the relation between Extraversion and emotionality of to-be-remembered events on the propensity to incur spontaneous false memories. Indeed, extravert individuals were less prone to produce false memories when exposed to positive episodes compared to negative ones. We note that the stable characteristics of the rememberer such as personality traits should be taken into consideration when studying emotional false memories. An individual differences approach on personality characteristics may indeed be very informative both at the theoretical level – illuminating how false memory is influenced not only by the contextual details or the transitory mood of the individual but also by their own internal structure – and at practice.
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Funding information This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. Acknowledgments We are grateful to Domonkos Attila Banki, Eufrasia Cormio and Gabriele Noaro for helping with data collection. Supplementary materials Supplementary material associated with this article can be found, in the online version, at doi:10.1016/j.paid.2020.109861. References Akaike, H. (1998). A bayesian analysis of the minimum AIC procedure. In E. Parzen, K. Tanabe, & G. Kitagawa (Eds.). Selected Papers of Hirotugu Akaike. Springer Series in Statistics (Perspectives in Statistics). New York: Springer. Baayen, R. H. (2008). Analyzing linguistic data: A practical introduction to statistics using R. Cambridge, UK: Cambridge University Press. Bookbinder, S. H., & Brainerd, C. J. (2017). Emotion and false memory: The contextcontent paradox. Psychological Bulletin, 142, 1315–1351. Burnham, K., & Anderson, D. (2002). Model selection and multimodel inference (2nd ed.). New York: Springer. Cloninger, C. R. (1999). The temperament and character inventory-revised. St Louis, MO: Center for Psychobiology of Personality, Washington University. Dazzi, C., Pedrabissi, L., & Santinello, M. (2004). EPQ-R eysenck personality questionnaire revised. Florence, Italy: Giunti OS Organizzazioni Speciali. Denkova, E., Dolcos, S., & Dolcos, F. (2012). Reliving emotional personal memories: Affective biases linked to personality and sex-related differences. Emotion (Washington, D.C.), 12, 515–5128. Derryberry, D., & Reed, M. A. (1994). Temperament and attention: Orienting toward and away from positive and negative signals. Journal of Personality and Social Psychology, 66, 1128–1139.
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Personality and Individual Differences journal homepage: www.elsevier.com/locate/paid
The power of extraversion? Reduced false memories for positive events a,⁎
a
b
Chiara Mirandola , Enrico Toffalini , Emilia Ferruzza , Francesca Pazzaglia a b
T
a
Department of General Psychology, University of Padova, via Venezia 8, Padova 35131, Italy Department of Developmental and Social Psychology, University of Padova, via Venezia 8, Padova 35131, Italy
A R T I C LE I N FO
A B S T R A C T
Keywords: Extraversion Personality traits Emotion False memories
Evidence on the relation between personality traits and false memories is scarce and partly contradictory. For example, extraverts have been found to be less suggestible to induced memory distortion (through the misinformation paradigm); however, they tend to produce a higher amount of spontaneous false memories (through the Deese-Roediger-McDermott paradigm). Whether Extraversion influences false memories for positive and negative events is unclear. The current study was aimed at clarifying the effects of Extraversion (Eysenck Personality Questionnaire) on false memories using an ecological paradigm for emotional events. Participants were 151 volunteering undergraduate students. Results showed that Extraversion predicted reduced false memories for positive events, compared to negative ones. No effects of Neuroticism and Psychoticism were found. Results are discussed in terms of the stable characteristics of the rememberer that may affect memory distortions.
1. Introduction That memory is a re-constructive process and may lead people to distortions is a matter of fact. A deluge of studies have revealed the primary role of emotion in influencing subsequent true and false memory. Specifically, there is evidence in favor of both enhanced (Porter, Taylor & Ten Brinke, 2008) and reduced (Mirandola, Toffalini, Ciriello & Cornoldi, 2017, 2014; Storbeck, 2013) false memories for emotional events. Also the transient mood states of the rememberer affect false memories. Positive moods typically lead to more false memories than negative moods (Storbeck & Clore, 2005), but this may depend more on arousal than valence per se (Mirandola & Toffalini, 2016; see Bookbinder & Brainerd, 2017 for a comprehensive review). Surprisingly, the stable characteristics of the rememberer, such as personality traits, have not received much attention. Some studies have focused on how general personality traits may influence susceptibility to memory distortions. For example, Porter, Birt, Yuille and Lehman (2000) investigated whether personality would correlate to susceptibility to recall false implanted childhood events after repeated interviews. The authors found that susceptibility to memory distortion was related to higher extraversion scores in the interviewer and lower extraversion scores in the participants. Extraverted interviewers may be more persuasive and successful in planting false memories in introverted individuals, who may be more compliant and thus more
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susceptible to believe to have experienced false events. On a similar venue, more suggestible participants (tested with the Gudjonsson Suggestibility Scale (GSS-2; Gudjonsson, 1997) recalled fewer detail of the original event (Liebman et al., 2001). Notably, the personality traits of extraversion and conscientiousness were associated with suggestibility on the GSS-2. A large study investigated the association between many personality traits and susceptibility to misinformation (Zhu et al., 2010). In this study personality was assessed with the Temperament and Character Inventory – Revised (Cloninger, 1999). The authors hypothesized a negative correlation between novelty seeking and false memory, based on previous evidence with extraversion – see Porter et al. (2000). Results showed that novelty seeking was indeed negatively correlated to overall false memory; however, this result was not confirmed when two extreme groups were created. Furthermore, individuals with high scores in cooperativeness, reward dependence and self-directedness, combined with low cognitive abilities, were most subject to misinformation. The authors are cautious in explaining the first result, and thus why do novelty seekers recall fewer false events remain somewhat unexplained. Novelty seekers share some characteristics with extraverts, including the need to find stimulation, the tendency to be enthusiastic and to explore the environment. Extraverts’ susceptibility to postevent information was found to be lower than that of introverts (Ward & Loftus, 1985). The explanation of this effect was rooted in extraverts’
Corresponding author. E-mail addresses: [email protected] (C. Mirandola), enrico.toff[email protected] (E. Toffalini).
https://doi.org/10.1016/j.paid.2020.109861 Received 17 January 2020; Accepted 22 January 2020 0191-8869/ © 2020 Elsevier Ltd. All rights reserved.
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photographs: 14 photographs depicted the most typical events of the episode (i.e., for the waking up episode, examples are getting dressed, having breakfast) and seven photographs depicted cause-effect scenes. Specifically, 1 photograph depicted the causal event (e.g., for the dating script, a girl approaching a boy waiting for her on a bench) and 6 photographs its outcome: two photographs depicted a neutral outcome (the girl and the boy are friends and meet for exchanging a book), 2 photographs a negative outcome (the boy being aggressive toward the girl for being late) and 2 photographs a positive outcome (the boy and the girl are kissing each other). Target-distractor photographs were counterbalanced across participants.
lower cortical arousal compared to introverts. Indeed Eysenck postulated that extravert people need to seek for outside stimulation given that their internal level of arousal is reduced; conversely, introvert's higher cortical arousal would lead them to seek for quiet and reliable situations and contexts (Eysenck, 1967). Given that high arousal may interfere with memory retention, it results that introverts are more prone to accept misleading information. However, in a study using a paradigm which elicits spontaneous false memories (Deese-Roediger-McDermott Paradigm; Roediger & McDermott, 1995), extraverts falsely recalled a substantially higher number of critical lures than introverts (Sanford & Fisk, 2009). This finding might be interpreted as a direct consequence of enhanced semantic priming effect, already evident in these individuals (Matthews & Harley, 1993). Extraverts’ predisposition induces a significant raise in the activation of the critical lure till it is recognized as a previously presented word. On the contrary, introverts were found to be less sensitive to memory distortions due to their restricted attentional focus, which reduces the spreading of activation. The extant literature is mixed, depending on the type of paradigm used. Furthermore, the specific relation between Extraversion and valence of to be-remembered events has been neglected. In terms of memory accuracy, extravert individuals reported a higher amount of happy than negative memories (Mayo, 1989). Furthermore, extravert individuals recollect more positive autobiographical memories whereas neurotic individuals recollect more negative ones (Denkova, Dolcos & Dolcos, 2012). Based on this evidence, in the current study we aimed at analysing whether individual scoring high in Extraversion – measured through the Eysenck Personality Questionnaire – would be less prone to false memories for positive events compared to negative or neutral ones, employing an ecological false memory task which induces spontaneous false memories for events. Investigating the relation between emotional memory and the two other facets of the Eysenck Personality Questionnaire – namely Neuroticism and Psychoticism – is more exploratory. Based on the literature on anxiety (Toffalini, Mirandola, Coli & Cornoldi, 2015; Toffalini, Mirandola, Drabik, Melinder & Cornoldi, 2014), we reasoned that people scoring high on Neuroticism would show higher production of negative false memories compared to positive ones. Furthermore, some studies showed the influence of Psychopathy (which is similar to Psychoticism) and Narcissism on memory. These personality traits are included in the “dark triad” model of personality and we preliminary conducted exploratory analyses to test whether there was any relation between the dark triad traits and false memories. We reported the relevant results in the Supplemental material.
2.2.2. EPQ-R questionnaire The Eysenck Personality Questionnaire – Revised (Eysenck, 1991) is a revised form of the traditional personality questionnaire assessing Extroversion, Neuroticism and Psychoticism. The Italian reduced version was administered which includes 48 items, 12 for each of the subscales (Dazzi, Pedrabissi & Santinello, 2004). Participants are required to choose between two yes/no questions for each item. Examples of items are the following: Extraversion: “Do you enjoy meeting new people?”; Neuroticism:“Are you a worrier?”; Psychoticism: “Do you prefer to go your own way rather than act by the rules?” 2.2.3. Control measures We administered the Questionnaire for the assessment of psychopathology in adolescence (QPAD; Sica, Chiri, Favilli & Marchetti, 2011) which is a broad-spectrum questionnaire designed to evaluate the presence of psychopathological symptoms. It is formed by 25 statements; responses are given on a 4 – point Likert scale ranging from 1 (false) to 4 (true) for each item. Only the depression and the anxiety subscales were measured, given their importance for the emotional memory domain (Toffalini et al., 2014, 2015). The depression and anxiety scores were treated as control variables in the subsequent analyses. We administered the forward and the backward digit span tasks (Wechsler, 2008). Participants are presented with sequences of digits of increasing length and difficulty. In the forward digit span task, individuals are required to repeat digits in the same order in which they were presented; in the backward digit span task, individuals are required to repeat digits in the opposite order in which they were presented. 2.3. Procedure All participants were tested individually at the Department of [BLINDED], University of [BLINDED]. Upon arrival, participants were initially administered the False memory task for emotional events.
2. Methods 2.1. Participants
2.3.1. Encoding phase Participants were instructed that they would see a series of photographs depicting people performing various everyday activities and that they would have to pay close attention to the stories. Each photo was shown for 2 s and was followed by a 2‑sec‑long black screen. The order of presentation of the 9 episodes was fixed, whereas target-distractor photographs and outcome's valence of each script were balanced across participants. The encoding phase was followed by a 15-min retention interval. During this interval, participants were administered the digit span tasks and the Q-PAD questionnaire.
A group of 151 undergraduate students from the University of [BLINDED] (Mean age = 22.5 years, SD = 2.2, Females = 129) participated in this study and received extra course credits. Written informed consent was obtained by all students prior to participation. The study was approved by the local ethical committee of the University of [BLINDED]. 2.2. Materials 2.2.1. False memory task for emotional events We tested emotional false memories with a paradigm including a series of photographs organized in nine episodes, depicting varying situations, such as waking up, going shopping, dating/meeting a friend, going to a birthday party, mountain climbing, playing at the slot machine, coming back from a journey, participating to a track competition and going on a bike trip (see Mirandola, Toffalini, Ciriello & Cornoldi, 2017 for an example). Each episode was comprised of 21 color
2.3.2. Recognition phase After the retention interval, participants received a surprise memory test. Stimuli for the recognition phase consisted of a set of 45 target and 45 distractor photographs presented in a randomised order. For each episode, four targets and four distractors were included. One of the four distractor photographs depicted the causal antecedent whose matching outcome had been presented at the encoding phase. Finally, 18 2
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model selection of alternative models. For parsimony and to avoid overly complex models, no interactions between more than two variables at a time were tested. Because a binomial variable was modelled, effect sizes were expressed by reporting estimated probabilities or odds ratios (OR). The latter were calculated as the exponential values of the model coefficients. As we rescaled all quantitative predictors to standardized normal distributions before the analyses, ORs represent the change in odds of a “yes” response (whether the dependent variable is causal errors, gap-filling error, or hit) for every increase of 1 SD of the predictor. ORs or estimated probabilities were reported only for effects that were found relevant using the model selection criteria described above.
Table 1 Mean proportion (and standard deviations) of causal errors, gap-filling errors, and hits. Valence Causal errors Gap-filling errors Hits Sensitivity index (d’)
Neutral .45 (0.34) .28 (0.23) .81 (0.14) 1.80 (1.08)
Negative .43 (0.33) .26 (0.22) .79 (0.17) 1.79 (1.09)
Positive .42 (0.32) .26 (0.21) .81 (0.16) 1.88 (1.08)
photographs inconsistent with any of the scripts were included (9 targets and 9 distractors). The memory test consisted of a self-paced yes/ no recognition task. In the case of a “yes” response participants were further asked to specify if they “remembered” or “knew” the photograph shown. Participants had to select the “remember” option when they could clearly remember the photo and could retrieve some qualitative details related to it. Conversely, they had to select the “know” option when they were familiar with it, but they could not retrieve any specific detail associated with it. At the end of the recognition phase, participants filled the personality questionnaires. Participants were then debriefed about the aims of the study. The entire experimental session lasted approximately one hour and a half.
3.1. Valence and control variables As a first step, we assessed the effects of Valence and the control variables to select a baseline model before testing the effects of the personality factors. The starting model was the one with the intercept alone. Subsequently, Valence was added, followed by the control variables and their interaction with Valence. Eventually, the model with the lowest AIC was kept as the baseline model for the subsequent phase in which the role of the personality factors was assessed. With regard to the fixed effect of Valence on causal errors, a significant main effect was not found, ΔAIC = +3.00, χ2(2) = 1.06, p = .59. The probability of producing causal errors is similar in the three emotional conditions and is reported in Fig. 1. The expected reduction of emotional false memories compared to neutral ones was found when we analysed the Remember responses associated to causal errors. In this case Valence reduce the AIC of the model and it had a significant main effect on Remember responses associated to causal errors, ΔAIC = −2.1, χ2(2) = 6.03, p = .049 (see Fig. 2). Compared to the neutral condition (i.e., the reference), errors in both the negative, OR = 0.76, 95% CI (0.52, 1.11), and positive conditions, OR = 0.62, 95% CI (0.42, 0.91), were less likely. As can be seen in Fig. 2, Remember responses are produced to a lower extent for both negative and positive false memories compared to neutral ones. Conversely, as expected, no main effect of Valence was found for Know responses associated to causal errors, ΔAIC = +3.2, χ2(2) = 0.80, p = .67. Nonetheless, all analyses presented subsequently were conducted on the overall causal errors, for consistency with previous reports. However, we ensured that the same conclusion were also valid for causal errors associated with Remember responses. Among the control variables, only the Q-PAD anxiety contributed to increase the model fit when entered as a main effect in addition to Valence, ΔAIC = −11.3, χ2(1) = 13.34, p < .001. Model coefficients showed that it had an overall positive effect on false memory, OR = 1.42, 95% CI (1.18, 1.73), such that higher anxiety was associated with a higher false memory rate.
3. Results We reported the mean proportions of causal errors, gap-filling errors, and hits for each valence condition for descriptive purposes (Table 1). As a preliminary step, we calculated the sensitivity d’ scores for each participant, divided by valence condition. In each condition, d’ was calculated as z (hit rate) – z (gap filling error rate); for rates equal to 1.00 or 0.00, we subtracted or added 0.01, respectively, to keep the d’ within the finite range. Causal errors were not included in this phase as they represent a specific kind of memory error which was treated separately. As can be seen in Table 1, d’ was rather high on average (around 1.80) and there was negligible variation across the three conditions. A mixed-effects linear model with valence condition as the fixed effect of interest, d’ as the dependent variable, and participants as random effects, suggested negligible effect of valence condition on d’ (likelihood-ratio test against a model without valence as the fixed effect was used): χ2(2) = 1.10, p = .58. As the data consisted of repeated measures of binomial type (“yes”: 1, or “no”: 0), data analysis was conducted using logistic mixed-effects models (Baayen, 2008; Jaeger, 2008). Causal errors were the “yes” responses to causal distractors. The fixed effects of interest were Valence (3 levels: neutral, negative, positive; the baseline was “neutral”), control variables (forward and backward digit span, and anxiety and depression scores of the Q-PAD), and the personality factors. Participants were treated as random effects. Model comparison was adopted to assess the relevance of the effects of interest. Model selection was based on the Akaike Information Criterion (Akaike, 1998; Burnham, Anderson & Lower, 2002). AIC indicates better fitting model, and it can be used both for nested models and models with alternative predictors. To give an idea of the amount of evidence provided, we adopted the rule of thumb proposed by Raftery (1995) with reference to the Bayes Factor (another type of evidence ratio). Following those guidelines, we suggest to interpret ΔAIC = −2.0 as positive evidence for an effect, and ΔAIC = −6.0 as strong evidence for an effect. Conversely, ΔAIC = +2.0 and ΔAIC = +6.0 were interpreted respectively as positive and strong evidence against an effect. Any |ΔAIC| < 2.0 (in absolute terms) suggests uncertainty in making a decision. For the effects of interest statistical significance was also assessed with likelihood ratio tests for nested models, based on the chi-square distribution (Pinheiro & Bates, 2000). Note that likelihood ratio test here can be used only for nested models, and thus it cannot serve for
Fig. 1. Emotional false memories. Estimated probability of causal errors as a function of valence. 3
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3.3. Accuracy The final model obtained on causal errors was fitted, in an additional analysis, also on the “hit” responses (i.e., on accuracy). However, none of the effects included in it adequately fitted accuracy. For the interaction between Extraversion and Valence, ΔAIC = + 2.7, χ2(2) = 1.33, p = .51 (for the main effect of Valence, ΔAIC = + 2.9, χ2(2) = 1.10, p = .58). For the control variable Q-PAD anxiety, ΔAIC = + 1.7, χ2(1) = 0.30, p = .59. The same was true for accuracy measured as d’ (see at the beginning of the Results section). 4. Discussion The stable characteristics of the rememberer – such as personality traits – have been neglected in the extant literature investigating the relation between emotional experiences and the tendency to incur spontaneous false memories. Specifically, evidence on Extraversion is contradictory, with studies showing extraverts’ diminished suggestibility to memory distortions - when misinformation paradigms are employed (Porter et al., 2000; Ward & Loftus, 1985) - and enhanced production of errors when associative memory paradigms that elicit spontaneous false memories are instead used (Sanford & Fisk, 2009). Spontaneous false memories have been studied employing the DRM (Deese-Roediger-McDermott) paradigm, which consists on the presentation of semantically related wordlists. Within each list, not only are words semantically related to each other (e.g., tired, pillow, bed) but they also converge in meaning to a nonpresented critical lure (e.g., sleep); recall or recognition of the critical lure at test represents a false memory. The fact that extravert people recall to a higher extent than introverts such critical lures, seems to be related to the semantic priming effect – boosted in extraverted. Indeed, this would make them falsely accept more critical lures into their memory.The current study was aimed at clarifying the effect of Extraversion on emotional false memories, using a false memory task that elicits spontaneous inferential false memories but it is indeed more ecological than wordslists. The main result was that Extraversion interacted with valence, such that higher scores in Extraversion predicted diminished false memories for positive compared to negative episodes. There is evidence that extraverts tend to manifest an attentional bias toward positive stimuli (Derryberry & Reed, 1994), which might suggest an enhanced elaboration of positive detail; this might in turn enhance memory accuracy for positively valenced events. Indeed, individuals with high levels of extraversion may focus their attention toward positive episodes, or rather they may encounter more difficulties disengaging from positive stimuli which are motivationally relevant to them, like it has been suggested (Denkova et al., 2012). In both cases, whether their attentional focus is biased toward positive stimuli or they are less able to disengage attention from positive ones, it results in extraverts’ diminished propensity to produce false memories. Indeed, encoding positive episodes under enhanced attentional focus results in subsequent reduced memory impairment at retrieval. This is confirmed also by the result on subjective recollection: extraverts do not only produce a lower amount of positive false memories but they also associate fewer Remember responses to them; thus, once false memories for positive events occur, they are not characterized by vivid remembering. A lower amount of Remember responses associated to emotional episodes (both negative and positive) compared to neutral ones is evinced also in the overall sample, regardless of individual differences in personality traits, extending to subjective recollection what was previously found on overall false memories (Mirandola et al., 2017). Nonetheless, we did not find a similar interaction between extraversion and valence on memory accuracy (i.e., hits, or true recognitions); it must be noted that the False memory task used in this study is specifically developed for eliciting inferential false memories; performance on memory accuracy is typically high and valence – or its interaction with individual differences - does not seem to influence true recognition (see
Fig. 2. Subjective recollection and false memories. Estimated probability of causal errors associated with Remember responses as a function of valence.
Any alternative model, including any other main effect or interaction with Valence, had a clearly worse fit than the best model, with all ΔAICs > +3.6.
3.2. EPQ-R personality factors and false memories As in the previous phase, we fit all models including the EPQ-R personality traits (i.e., Extraversion, Neuroticism, Psychoticism) and their combination. Factors were not taken into consideration for more complex models if they worsened the fit. Up to two-way interactions with Valence were also considered. The best fitting model added a two-way interaction between Valence and Extraversion, and a main effect of Neuroticism, to the baseline model, ΔAIC = −6.9. Compared to this model, the second best one included also Psychoticism, but it had a rather worse fit, ΔAIC = +1.7. All other alternative models had clearly worse fit, all ΔAICs > +2.9. With regard to the best model, the two-way interaction between Valence and Extraversion reached statistical significance when compared against the nested model that included only the main effects, ΔAIC = −4.1, χ2(2) = 8.11, p = .02 (see it detailed below). Unsurprisingly, also the main effect of Neuroticism was significant, ΔAIC = −2.9, χ2(1) = 4.92, p = .03. Looking at the model parameters suggested that Neuroticism had a negative effect on false memory, OR = 0.77, 95% CI (0.61, 0.97). This seems at odds with the fact that a conceptually related measure such as Q-PAD anxiety had an enhancing effect on false memory, casting a doubt that this effect of Neuroticism may be due to a near-overfitting effect linked to the fact that Q-PAD anxiety and Neuroticism indeed correlate strongly, r = 0.61. This suspicion is strengthened by the fact that, if Q-PAD anxiety was not controlled for in the model, then Neuroticism had not effect on false memory and it would even worsen the model fit, ΔAIC = +2.0, χ2(1) = 0.03, p = .87. For all these reasons, we eventually chose to exclude Neuroticism from the final model. Therefore, the latter had the following predictors: Q-PAD anxiety (as a control variable), and Valence in interaction with Extraversion. With regard to the two-way interaction between Extraversion and valence, it is depicted in Fig. 3. As compared to the neutral condition, the contrast for the negative condition was OR = 1.28, 95% CI (0.96, 1.71), for the positive condition it was OR = 0.84, 95% CI (0.62, 1.13). Both visual inspection of Fig. 3 and the consideration of the model parameters suggested that the clearest contrast within the model indicated a diverging effect of Extraversion on negative vs positive false memory, OR = 1.52, 95% CI (1.14, 2.03). It should be noted that when only causal errors associated with Remember responses were considered, the same final model was obtained, and with similar effects. 4
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Fig. 3. Personality and false memories. Estimated probability of causal errors as a function of Extraversion and Valence.
Mirandola et al., 2014, 2017). To conclude, the current study brought evidence in favor of the relation between Extraversion and emotionality of to-be-remembered events on the propensity to incur spontaneous false memories. Indeed, extravert individuals were less prone to produce false memories when exposed to positive episodes compared to negative ones. We note that the stable characteristics of the rememberer such as personality traits should be taken into consideration when studying emotional false memories. An individual differences approach on personality characteristics may indeed be very informative both at the theoretical level – illuminating how false memory is influenced not only by the contextual details or the transitory mood of the individual but also by their own internal structure – and at practice.
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