Special Thematic Section " Collective Memories and Present-Day Intergroup Relations : A Social-Psychological Perspective " Fostering Trust and Forgiveness Through the Acknowledgment of Others ’ Past Victimization

The present work examines the acknowledgment of past ingroup victimization by adversary outgroup leaders as an effective means to promote intergroup trust. More specifically, through an experimental study we demonstrated that Israeli-Jewish participants who were exposed to Palestinian leaders’ messages acknowledging the Jews’ suffering from anti-Semitic persecutions (past victimization condition) displayed more trust toward outgroup leaders than participants who were exposed to messages acknowledging the Jews’ sufferings from the ongoing conflict (present victimization condition) and participants who were exposed to a control message condition. Further, trust mediated the relationship between acknowledgment of past victimization by rivals and forgiveness toward the outgroup as a whole. The implications of these results for restoring fractured intergroup relations are discussed.


Background
Intractable conflicts are conceived as protracted conflicts that are perceived by both parts as unsolvable and of zero-sum nature.Our work proposes a possible avenue for improving relations between groups entrapped in intractable conflicts by considering the Israeli-Palestinian case, the most representative example of these conflicts.

Why was this study done?
Literature on reconciliation has consistently demonstrated that the symbolic acknowledgement of the rivals' sufferings due to the ongoing conflict is particularly important to restore conflictual relations.Acknowledging these sufferings is especially difficult in intractable conflicts, as both the involved parties tend to compete over which group is suffering more.However, this acknowledgment could not necessarily focus only on the present-day conflict but also focus on sufferings belonging to the group's collective memories.Volkan (2001) argued that in virtually every large group there exists a mental representation of a central traumatizing past event which is called the group's 'chosen trauma'.It represents a key component of the collective identity and deeply shapes the group members' behaviors and their perceptions during the times of conflict.The main goal of the present study is to explore whether for group members (i.e., Israeli-Jews) the acknowledgment by rival representatives (i.e., Palestinian leaders) of this chosen trauma (i.e., anti-Semitic persecutions) would be a means for promoting trust and increasing the likelihood of enduring reconciliation even more effectively than the acknowledgment of the sufferings due to the ongoing conflict.
Literature on intergroup reconciliation considers the acknowledgement of adversaries' sufferings as a crucial factor to move forward toward a path of peace (Čehajić-Clancy, Effron, Halperin, Lieberman, & Ross, 2011;Nadler, 2012).Previous research has provided evidence that acknowledging the outgroup's victimization through the ingroup's wrongdoings is one of the most effective means for restoring fractured intergroup relationships (see, e.g., David & Choi, 2009;Maoz & Bar-On, 2002;Vollhardt, Mazur, & Lemahieu, 2014).Acknowledging these sufferings can be especially difficult in intractable conflicts.Indeed, in these zero-sum conflicts the involved parties are particularly prone to claim their victim status and to compete over which group's sufferings are more severe (Kelman, 2008;Noor, Shnabel, Halabi, & Nadler, 2012).
However, the acknowledgment of others' sufferings may not only focus on the ongoing conflict.For many groups, past experiences of victimization are an important component of their collective memories that affect their responses to events as much or even more than present experiences of victimization (Licata & Mercy, 2015;Volkan, 2001).Thus, the recognition by rivals of these past traumatic events may represent for such groups a meaningful gesture that would help them to develop trust in their rivals and, consequently, to show conciliatory attitudes.
A common way of expressing acknowledgment of suffering and of offering gestures of reconciliation is through group representatives such as leaders.In this context, the present research aimed to demonstrate that in intractable conflicts the acknowledgment of rivals' suffering from past trauma is a strategy that may enhance outgroup trust even more than the acknowledgment of present suffering due to an ongoing conflict.More specifically, our main aim was to empirically demonstrate that for Israeli-Jews the acknowledgment by rival leaders (i.e., Palestinian leaders) of the anti-Semitism suffered by Jews throughout the centuries would increase trust toward outgroup leaders more than their acknowledgment of the Israeli-Jews' victim status due to the ongoing conflict.Further, we explored whether this increased trust toward outgroup leaders would, in turn, increase forgiveness toward outgroup members and explain the relationship between acknowledgment of past victimization and willingness to forgive outgroup members.

Collective Memories and Past Victimization in Intractable Conflicts
Collective memories refer to representations of a shared past "that are retained by members of a group, large or small, that experienced it" (Schuman & Scott, 1989, pp. 361-362).These shared representations are helpful to the group and its members for a variety of reasons.For example, they contribute to maintaining a positive image of the group and give group members a sense of continuity of their own group (Bellelli, Bakhurst, & Rosa, 2000;Sani et al., 2007).Further, collective memories align group values and norms by helping group members to define what courses of action are appropriate in the present and the future (Liu & Hilton, 2005).
Within the context of intractable conflicts, past events of ingroup victimization are often key elements of collective memories, that give group members an explanation about the origins of the ongoing conflict and options for its resolution (Paez & Liu, 2015).In his influential analysis of the psychological aspects of international conflicts, Volkan (2001) has suggested that in virtually every large group there exists a mental representation of a central traumatizing past event which becomes the group's "chosen trauma", and that "by sharing the chosen trauma members of the group are linked together" (p.88).Chosen trauma is said to have an especially strong influence on group members' behavior and their perceptions during times of conflict.At these times, representations of past and present enemies blend and form the basis for feelings of entitlement which justifies violence against the ingroup's present day adversary (Volkan, 1997(Volkan, , 2001)).In the Israeli-Palestinian conflict, "chosen trauma" are a core element in the parties' identities.For Israeli-Jews, the chosen trauma consists of memories of two millennia of anti-Semitic persecutions that culminated in the Holocaust.For Palestinians, the chosen trauma is linked to the creation of Israel in 1948 which left many of them as refugees.They label this historical event as the "Naqba" (i.e., the catastrophe; Roberts, 2013).In the present study we focus on the effects of Palestinians' acknowledgment of Jewish "chosen trauma" (i.e., anti-Semitic persecutions) on Israeli-Jews' conciliatory attitudes towards Palestinians.Social psychological literature also empirically shows the negative consequences of this "chosen trauma" on the present conflictual relation between Jews and Palestinians (Klar, Schori-Eyal, & Klar, 2013).For example, Wohl and Branscombe (2008; Study 1) demonstrated that Canadian Jews who were primed with the victimization of Jews during the Holocaust displayed less collective guilt for their group's harmful actions toward the Palestinians.
Moreover, Israelis' and Palestinians' competition over victimhood is one reason for the protracted nature of their conflict.Competitive victimhood, which consists of each party's effort to minimize its adversary's past sufferings while magnifying its own, is common in other relatively protracted conflicts (e.g., Catholics and Protestants in Northern Ireland) and is negatively associated with willingness for reconciliation (Noor et al., 2012).This begs the question of how these negative consequences of collective victimhood on current intergroup relations can be ameliorated.
One way of doing so is by inducing the two adversarial parties to view themselves as victims of the conflict between them.In fact, when Israelis and Palestinians viewed both themselves and the adversary as victims of the conflict this led to more willingness to reconcile and less competitive victimhood (Shnabel, Halabi, & Noor, 2013).A second way to overcome the negative consequences of victimhood on intergroup relations is by acknowledging the adversary's past victimization.For example, Americans of Armenian descent who learned that Turkish opinion leaders acknowledge the Armenian genocide reported more readiness to reconcile with Turks than when the Turkish opinion leaders had not acknowledged the Armenian genocide.Similarly, American Jews were more willing to reconcile with Poles and Germans when these latter had been said to have acknowledged Jewish sufferings in the first half of the past century than when they had not (Vollhardt et al., 2014).In another recent demonstration of the ameliorative effects of the acknowledgment of past adversary's victimization, Hameiri and Nadler (2017) showed that when Israeli-Jews and Palestinians learned that their adversary acknowledged their "chosen trauma" related sufferings (i.e., the Holocaust and Naqba, respectively), they were more willing to compromise for peace.These positive effects were explained by different mechanisms, including a satisfied need to be morally accepted by the outgroup (Nadler & Shnabel, 2015;Shnabel & Nadler, 2015) and increased trust in the adversary.
Despite the great relevance of these findings, they do not allow to fully establish the unique contribution of the acknowledgment of "chosen trauma" on the reconciliation process.More specifically, because these past findings are based on the acknowledgment of "chosen trauma" (e.g., anti-Semitism for Jews, Armenian genocide for Armenians, the Naqba for Palestinians), they do not allow to assess if this form of acknowledgment is a more potent intervention than the acknowledgment by rivals of the victimization due to the ongoing conflict.This latter issue appears to be especially important, because in intractable conflicts competitive victimhood dominates (Kelman, 2008;Noor et al., 2012) and renders the mutual acknowledgment of victimization due to the present conflict as particularly difficult.The acknowledgment of a past "chosen trauma" may be unrelated to the ongoing mutual victimization and could therefore be a more accessible way to ameliorate the fractured intergroup relations.
Based on these insights, the present work aims to better understand the unique role of the acknowledgment of past victimization by rivals, showing that it could entail more positive effects than the acknowledgment of the victimization due to the ongoing conflict.In particular, we assumed that for Israeli-Jews the acknowledgment of chosen-trauma related victimization (i.e., anti-Semitic persecutions) by Palestinians, would be a more powerful strategy than the acknowledgment of present victimization in fostering trust toward the adversaries.The theoretical rationale underlying this hypothesis is outlined next.

Intergroup Trust in Conflictual Settings
A great deal of literature has shown that intergroup trust is a key factor in promoting peaceful relations in conflictual or post-conflictual settings (e.g., Andrighetto, Mari, Volpato, & Behluli, 2012;Čehajić, Brown, & Castano, 2008;Noor, Brown, Gonzalez, Manzi, & Lewis, 2008;Noor, Shnabel, Halabi, & Doosje, 2015).Indeed, trust allows the involved parties to overcome the belief that others have negative intentions toward the ingroup (Mitchell, 2000) and encourages the development of cooperative and altruistic behaviors (Kramer & Carnevale, 2001).It also enables individuals to take the risk of being vulnerable and to make conciliatory initiatives to the other side, with some degree of assurance that they will not be exploited (Dovidio, Gaertner, Kawakami, & Hodson, 2002).A number of studies found that increased trust toward outgroup members or their leaders is a necessary precursor of forgiveness (see Hewstone et al., 2008).Further, in the absence of trust, conciliatory gestures by the rivals may be perceived as driven by instrumental intentions.For example, Nadler and Liviatan (2006) showed that for Israeli-Jews with low levels of trust toward Palestinians the empathic message from a Palestinian leader had a "boomerang effect" by decreasing their willingness to reconcile with outgroup members.In considering the conflictual relation between the two main linguistic communities in Belgium, Alarcón-Henríquez and colleagues (2010) also showed that high-trusting -but not low-trusting -Dutch-speaking participants displayed positive attitudes toward their French-speaking counterparts when the latter acknowledged the importance of shared past sufferings.Thus, these previous studies suggest that outgroup trust plays an essential role in translating positive messages from outgroup members into positive orientations toward them (see also Hameiri & Nadler, 2017).
The purpose of the current work is to more deeply investigate the unique contribution of the acknowledgment of past victimization in increasing outgroup trust, by demonstrating that this acknowledgment would elicit outgroup trust in a more effective way than the acknowledgment of victimization due to the ongoing conflict.The rationale underlying this key hypothesis is based on two main assumptions.The first one grounds in the centrality of acknowledged trauma for collective identity and memories: If one accepts the idea that for many groups trapped in intractable conflicts the "chosen trauma" -anti-Semitism for Israeli-Jews in our context -is a key component of their collective identity (Volkan, 2001), then acknowledging it would transmit a particularly strong message of respect toward the other group that could elicit trust in a way even stronger than the acknowledgment of present victimization.The second assumption integrates the previous one and is perhaps more specific to the current context: We argue that it is easier to trust outgroup leaders when they acknowledge a past victimization in which they did not have any active involvement than when they acknowledge a present victimization in which they have an active involvement (i.e., the ongoing Israeli-Palestinian conflict).Put differently, when compared with the acknowledgment of present victimization, the acknowledgment of past victimization should be less prone to induce mistrust and assumptions about the outgroup's hidden motivations especially if they were not involved in the past victimization.

The Present Research
An experimental study was designed to test our hypotheses.As mentioned above, we focused on the context of the Israeli-Palestinian conflict, which is considered one of the most intractable and central intergroup conflicts in today's world.During the last decades, the conflict has gone through various and alternating phases but still remains unresolved, despite several bilateral attempts or third-party interventions aimed to restore peace.In fact, this is an existential conflict in the sense that it constitutes a conflict between two national movements who view the same land as their ancestral home.
Participants were Israeli-Jewish citizens who were randomly exposed to one of three different messages supposedly composed by a Palestinian leader.We hypothesized that a) participants exposed to a message acknowledging the past ingroup's victimization (i.e., the anti-Semitic persecution of Jews in Europe) would display greater trust toward the outgroup leaders than participants who were exposed to a message acknowledging the present ingroup's victimization (i.e., terrorist attacks during the Israeli-Palestinian conflict) or to a control message (i.e., eating habits of the two groups); b) trust toward the outgroup leaders, in turn, would be positively linked with intentions to forgive the rival group as a whole; and c) trust toward outgroup leaders would mediate the overall positive effect of ac-knowledgment of past victimization (vs.present victimization vs. control condition) on willingness to forgive the outgroup.

Method Participants and Design
Participants were 115 (56 female) Israeli-Jewish students voluntarily recruited from a large Israeli university.Their mean age was 31.70 years (SD = 12.48; range: 19-67).They were randomly assigned to one condition in a threelevel (type of message: acknowledgment of past vs.present victimization vs. control condition) between-subjects design. i

Procedure
Participants were examined individually.After providing their informed consent, they completed a two-part questionnaire that was presented to them as a survey on attitudes related to media communication (for a similar procedure used in the same context see Nadler & Liviatan, 2006;Shnabel, Nadler, Ullrich, Dovidio, & Carmi, 2009).
In the first part of the questionnaire, participants were asked to provide demographic information.Then, to bolster the cover story, they were asked to answer a set of items investigating their media consumption and their attitudes toward popular media.
In the second part of the questionnaire, participants were first exposed to the experimental manipulation: They were asked to read an excerpt from a speech allegedly held by a Palestinian political leader during a political meeting and transmitted by many local channels.
ii The type of the message conveyed by the leader varied depending on the experimental condition (for the full messages see the Appendix).In the condition of acknowledgment of past victimization, the message focused on the importance of acknowledging the Jews' suffering due to anti-Semitism.In the condition of acknowledgment of present victimization, the politician's message focused on the importance of acknowledging the Jews' suffering due to the Israeli-Palestinian conflict.In the control condition, the politician's message focused on the Jews' and Palestinians' eating habits.
After reading the message, participants were presented with a manipulation check aimed at verifying whether they had understood the message content.For all conditions, they were asked to report on a 7-point scale (1 = not at all; 7 = very much) the extent to which they perceived the message as expressing the acknowledgment by the Palestinian leader of the Jews' sufferings during the ongoing conflict.The item was then reverse scored so that higher scores indicated more trust toward outgroup leaders.Further, a four-item scale (α = .75)adapted by Čehajić and colleagues (2008) measured the extent to which the message increased the participants' willingness to forgive outgroup members.The items were the following: The message "increases my willingness to forgive Palestinians for the misdeeds that they committed against my group", "helps me to draw a line under the conflicting past between Jews and Palestinians and to move forward", "prepare myself to forgive Palestinians for the misdeeds that they committed against my group", "makes me think that the misdeeds that Palestinians committed against my group are unforgivable (reverse-coded item).
Finally, participants were thanked and thoroughly debriefed.

Manipulation Check
An ANOVA of the manipulation check item showed a significant effect of the type of message, F(2,114) = 70.64,p < .001,η p 2 = .56.Bonferroni-adjusted pairwise comparisons indicated that participants who read the message that acknowledged their present victimization judged the message content as stressing more the Jews' sufferings due to the ongoing conflict (M = 6.27;SD = 1.25) than those who read the message that acknowledged their past victimization (M = 2.95; SD = 2.35), p < .001,and those who were assigned to the control condition (M = 1.70;SD = 1.36), p < .001.Further, those who were assigned to the condition of acknowledgment of past victimization perceived the message as focusing more on the present-day Jews' sufferings than those who were assigned to the control condition, p = .008.

Main Analyses
A series of univariate ANOVAs was then conducted to test the effects of the type of message (acknowledgment of past vs.present victimization vs. control) on the dependent variables of trust toward outgroup leaders and willingness to forgive outgroup members.For trust toward outgroup leaders, results showed a significant main effect of the type of message, F(2,114) = 4.16, p = .018,η p 2 = .07.Bonferroni-adjusted pairwise comparisons revealed that respondents who were exposed to the message that acknowledged the past victimization displayed higher levels of trust toward outgroup leaders (M = 3.58, SD = 1.81) than respondents who were exposed to the message that acknowledged the present victimization (M = 2.61, SD = 1.79), p = .04,or assigned to the control condition (M = 2.59, SD = 1.54), p = .047.Further, pairwise comparisons revealed that participants assigned to the condition of acknowledgment of present victimization and those assigned to the control condition did not differ significantly from each other, p = 1.00.
For the willingness to forgive outgroup members, results showed a significant effect of the type of message, F(2,114) = 11.34,p < .001,η p 2 = .17.Bonferroni-adjusted pairwise comparisons indicated that participants who read the Palestinian leader's message regarding their past victimization displayed greater willingness to forgive Palestinians (M = 3.64, SD = 1.47) than participants assigned to the control condition (M = 2.27, SD = 0.99), p = .001,but not compared to participants who read the message regarding their present victimization (M = 3.37, SD = 1.33), p = 1.00.Further, participants assigned to the condition of acknowledgment of present victimization displayed greater willingness to forgive outgroup members than those assigned to the control condition, p = .001.
Then, we verified our main mediation hypothesis by running a mediational model through the PROCESS macro Model 4 for SPSS with 1000 bootstrapping samples (Hayes, 2013).In this model, the type of message was entered as the independent variable, trust toward outgroup leaders as the mediator, and willingness to forgive outgroup members as the outcome variable.Furthermore, because the independent variable was categorical with three levels, we followed Hayes and Preacher's (2014) recommendations and generated two dummy-coded variables with the condition of the acknowledgment of past victimization as the reference group (for a similar procedure see, Baldissarri, Andrighetto, Gabbiadini, & Volpato, 2017;Galdi, Cadinu, & Tomasetto, 2014).In particular, Contrast 1 tested the effect of the condition of acknowledgment of past victimization (coded 0) versus the condition of acknowledgment of present victimization (coded -1), with the control condition coded 0. Contrast 2 tested for the residual difference between the condition of acknowledgment of past victimization (coded 0) versus the control condition (coded 1), with the condition of acknowledgment of present victimization coded 0.
iii The analysis showed

Discussion
In line with our hypotheses, results showed that for Israeli-Jewish participants the acknowledgment of past victimization due to anti-Semitic persecutions was an effective strategy to build trust toward Palestinian leaders.Notably, by extending the work by Hameiri and Nadler (2017), our study revealed that this strategy is even more effective in increasing trust than the acknowledgment by the same leaders of the ingroup's sufferings due to the present conflict.In turn, this enhanced trust toward outgroup leaders increased the willingness to forgive the outgroup as a whole.

Collective Memories and Present-Day Intergroup Relations
We believe that our findings may have several theoretical and practical implications.First, they shed new light on the consequences of collective memories for present day intergroup relations.So far, most of the research in this field has documented the detrimental potential of collective memories in maintaining and legitimizing intergroup conflicts, especially when these memories concern past experiences of collective victimization (e.g., Bar-Tal, Chernyak-Hai, Schori, & Gundar, 2009;Wohl & Branscombe, 2004).Indeed, shared representations of past victimization often lead group members to assume the position of victims and, thus, to perceive aggressive or retaliatory acts perpetrated against outgroup members as more justified and legitimate (Bar-Tal et al., 2009).In the present work, we show that the acknowledgment of a core feature of these collective memories (i.e., shared past trauma) by rivals has beneficial effects for present-day intergroup relations by increasing trust toward the outgroup leaders who recognized this victimization.This trust, in turn, enhances willingness to forgive the outgroup as a whole.
Our results replicate and extend those by Alarcón-Henríquez and colleagues (2010) who, in considering the Belgian context, revealed that high-trusting Dutch-speaking participants were willing to reconcile with the French-speaking counterpart when this latter acknowledged the importance of shared past sufferings.Indeed, both studies highlighted how the acknowledgment of rivals' past sufferings may contribute to the restoration of fractured intergroup relations.However, while Alarcón-Henríquez and colleagues (2010) showed this effect in a conflictual but nonviolent intergroup context, in the current study we demonstrated that this recognition could have beneficial effects also in a context of protracted violence, such as that between Israeli-Jews and Palestinians.

Trust and Reconciliation
In this study we considered intergroup trust as a relevant outcome, rather than a condition that renders recognition of suffering effective.In this sense, it seems plausible to assume a recursive relationship between acknowledgment of suffering by rivals and intergroup trust: On the one hand, such acknowledgment contributes to intergroup trust, on the other hand, sufficient levels of intergroup trust are necessary for the positive effects of this acknowledgment to unfold (see also Nadler & Liviatan, 2006), especially if this acknowledgment concerns an ongoing victimization.
A specific (null) result which emerged in our work could provide us with important insights about this latter assumption: Participants in the condition of the acknowledgment of present victimization displayed the same levels of trust as participants in the control condition.Thus, the message acknowledging present victimization does not seem to have elicited trust among these participants.As we discussed earlier, acknowledgment of present victimization might not have increased trust because the conflict between Israeli-Jews and Palestinians is characterized by heavy suspicion.In this context, recipients would probably consider a rival's message acknowledging present victimization with caution because of their active involvement in this suffering.
Our work also contributes to the literature on intergroup reconciliation (see Nadler, Malloy, & Fisher, 2008) by demonstrating that acknowledgment of (past) victimization can be another strategy to build intergroup trust in the present day.This strategy may work in synergy with other strategies that have proven effective in increasing trust within these contexts, such as direct (Tam, Hewstone, Kenworthy, & Cairns, 2009) or extended contact (Andrighetto et al., 2012).

Implications for Intractable Conflicts
To the best of our knowldege, this is the first study showing that the acknowledgment of past victimization by rivals could be even more powerful in promoting trust and willingness to forgive outgroup members than the acknowledgment of victimization due to the ongoing conflict.This finding could have important practical implications especially within intractable conflicts, where the involved groups are particularly prone to claim their victim status (Noor et al., 2012) and the acknowledgment of others' sufferings due to the ongoing conflict is especially difficult to achieve.However, it is important to identify possible boundary conditions of our findings.First, we argue that beneficial effects of acknowledgment of past ingroup suffering can be achieved only if the recognized victimization constitutes an essential and salient part of the respective group's collective memories.The process in which an event of victimization is integrated into the group's collective identity and becomes a 'chosen trauma' unfolds over time.Current, or very recent, events of victimization are unlikely to assume the role of "chosen trauma" within collective identity.For example, an analysis of societal attitudes towards survivors of the Jewish Holocaust indicates that immediately after the traumatic event society harnesses its energy to 'heal the wounds', 'rebuild', and 'punish' the perpetrators.Only after time has passed victimization becomes part of the societal historical narrative and may turn into a "chosen trauma" that is central to collective identity (Nadler, 2001).Second, this strategy could be particularly functional when targeting groups that occupy the high-power position, or that feel they are perceived by third parties as potential perpetrators in an intractable conflict.Indeed, acknowledging a past episode of violence in which these high-power groups are undoubtedly positioned as victims should satisfy their need for acceptance and sympathy (Nadler & Shnabel, 2015).

Limitations and Future Directions
There are some limitations that should be considered in interpreting our findings and in determining the direction of future research.First, our single study does not allow us to establish with certainty whether our results can be extended to other conflictual contexts or groups.In particular, future studies are needed to verify whether a similar pattern of results emerges also when considering a different "chosen trauma" than anti-Semitic persecutions and a different high-power group than Israeli Jews.It would also be important to investigate whether our findings indeed pertain only to powerful groups or can be extended to relatively powerless groups.In fact, it is also possible that the acknowledgment of past experiences of victimization by rivals could have beneficial effects for groups positioned as victims or occupying low power positions, although these effects should then be driven by different underlying needs.For example, in the ongoing Israeli-Palestinian conflict the acknowledgement of the Nakba by Jewish-Israeli leaders could increase Palestinians' trust (see Hameiri & Nadler, 2017) and willingness to forgive outgroup members, as it may well fit with their need of empowerment.
Second, in our study we considered the acknowledgment of rivals' chosen trauma as a sort of "unilateral act" rather than a true interaction between the two involved groups.In particular, future studies should investigate whether a "reciprocal acknowledgment" of the respective chosen trauma would lead to a greater decrease of competitive victimhood rather than the unique acknowledgment by rivals of ingroup's chosen trauma or the salience of common victimhood due to the ongoing conflict.Indeed, a "reciprocal acknowledgment" may combine the two key mechanisms that disarm competitive victimhood, that is the perception that both groups share experiences of victimization and the need that others acknowledge ingroups' sufferings (see e.g., Noor et al., 2012).Thus, if one group acknowledges the rival's "chosen trauma" and this is reciprocated by the rival's acknowledgment of its chosen trauma, then both groups could share a victimization which is central for their respective group identity and which is acknowledged by rivals.
Third, from a methodological point of view, our findings are limited by the operationalization of the concept of trust.
As in previous work (see Hameiri & Nadler, 2017;Nadler & Liviatan, 2006), we assessed trust using a single-item indicator that arguably measured distrust rather than trust toward outgroup leaders.Indeed, although trust and distrust are commonly perceived as the opposite ends of the same continuum, some authors (e.g., Lewicki, McAllister, & Bies 1998) highlighted the qualitative differences between these two constructs and argued that they should be examined separately.Thus, a multiple-item scale directly assessing trust would surely be preferable and should be employed in future studies.
Fourth, it is important to note that our student sample is not representative of the general population, which may restrict the external validity and generalizability of our findings.Future studies should replicate our findings by considering a more representative sample of Jewish-Israeli participants.

Conclusions
Building trust in conflictual intergroup contexts is one of the most important challenges facing us today, but also one of the most complex.The official or symbolic acknowledgement of the suffering of an adversary outgroup by group representatives is particularly important to promote trust and increase the likelihood of enduring reconciliation.
Our findings suggest that this acknowledgment should also focus on suffering that is part of the adversary outgroup's collective memories.Indeed, this kind of acknowledgment could emerge as a "less costly" and more powerful strategy than the recognition of outgroup sufferings due to the ongoing conflict.

Notes
i) Although we did not conduct an a priori power analysis, a post hoc power analysis indicated that our sample size had power of 80% to detect small to medium effect sizes.
ii) The experimental texts were developed by the authors of the current paper by adapting messages employed in previous research (see e.g., Shnabel et al., 2009) to the scope of this research.
iii) Following the Hayes and Preacher (2014) procedure, when testing the effect of Contrast 1 and 2 on trust (mediator variable) and willingness to forgive (outcome variable), the other contrast was entered in the model as covariate.
Then, our main dependent variables were assessed.The level of trust toward outgroup leaders was measured through a single-item measure (for a similar measure seeHameiri & Nadler, 2017; Studies 2 and 3).Respondents were asked to indicate on a 7-point scale (1 = totally disagree; 7 = totally agree) their degree of agreement or disagreement with the following item: "In general, I don't have much faith in what the Palestinian leaders say." that both Contrast 1, b = 0.97, SE = 0.38, t(2,112) = 2.52, p = .013and Contrast 2, b = 0.99, SE = 0.40, t(2,112) = 2.45, p = .016,led to increased trust toward outgroup leaders, confirming the results of the previous univariate analyses.In turn, increased trust positively affected participants' willingness to forgive outgroup members, b = 0.14, SE = 0.07, t(3,111) = 2.03, p = .044.Crucially, confirming our mediational hypothesis, the indirect effect of the experimental condition on willingness to forgive outgroup members via trust toward outgroup leaders was significant, a*b = 0.14, SE = 0.09, 95% CI [0.011, 0.392] for Contrast 1 and a*b = 0.14, SE = 0.09, 95% CI [0.018, 0.382] for Contrast 2. Figure 1 summarizes the results for Contrast 1.

Figure 1 .
Figure 1.Results of mediation analyses testing the indirect effects of acknowledgment of past victimization (vs.acknowledgment of present victimization) on willingness to forgive via trust toward outgroup leaders.Contrast 1.