Mere acceptance or implicit forgiveness?
McCullough et al. propose “acceptance” as a means of tolerating the transgressor's Welfare Tradeoff Ratio (WTR; Tooby et al. Reference Tooby, Cosmides, Sell, Lieberman, Sznycer and Elliott2008). Despite establishing one plausible behavioral option to the infliction of interpersonal harm, we deem McCullough et al.'s notion elusive for two reasons:
First, it neglects the possibility that accepting an injustice may be equivalent to what Exline and Baumeister (Reference Exline, Baumeister, McCullough, Pargament and Thoresen2000) termed implicit forgiveness. Whereas explicit forgiveness (a) directly relates to an existing debt and (b) acknowledges one's willingness to absolve the transgressor from his or her guilt (e.g., “I forgive you for cheating on me”), the offended person may also implicitly express forgiveness – either by downplaying the transgression, for example, by saying “It's okay,” or wordlessly by maintaining contact with the transgressor and thus not ceasing the relationship. Along this line, the concept of implicit forgiveness differs from mere acceptance in the sense that a motivation to engage in retaliatory aggression changes into forgiving motivations, but no direct reference is made to the cancelled debt (cf. Exline & Baumeister Reference Exline, Baumeister, McCullough, Pargament and Thoresen2000). We therefore think that implicit forgiveness may also represent a possible adaptive mechanism when perceiving a social norm violation.
Second, one important question remains unanswered: What if the victim, for reasons of introspective limits (Nisbett & Wilson Reference Nisbett and Wilson1977), explicitly reports that he or she is okay with the aggressor's WTR, yet, implicitly, it reveals that he or she is still holding grudges? In order to provide empirical evidence for McCullough et al.'s suggestion that acceptance is marked by an absence of residual motivation to engage in retaliation, the use of indirect forgiveness measures seems beneficial. Consistent with the notion that cognitive accessibility of the self through introspection is limited (Greenwald & Banaji Reference Greenwald and Banaji1995; Greenwald et al. Reference Greenwald, Banaji, Rudman, Farnham, Nosek and Mellott2002), indirect measures such as the Implicit Association Test (IAT; Greenwald et al. Reference Greenwald, McGhee and Schwartz1998) capture information processing that resides outside conscious control or awareness (e.g., Asendorpf et al. Reference Asendorpf, Banse and Mücke2002; Greenwald & Banaji Reference Greenwald and Banaji1995; Wilson et al. Reference Wilson, Lindsey and Schooler2000). Hence, developing an indirect forgiveness measure could not only favor a multi-method approach (Eid & Diener Reference Eid, Diener, Eid and Diener2006), but also elucidate phenomenological differences between acceptance and implicit forgiveness.
Investigating the neural substrates of revenge and forgiveness: An fMRI approach
We concur with McCullough et al. that making adaptive decisions about revenge and forgiveness encompasses multiple cognitive components. Judging the forgivability of another's actions is one such component (Farrow et al. Reference Farrow, Zheng, Wilkinson, Spence, Deakin, Tarrier, Griffiths and Woodruff2001). For example, a post-therapy fMRI study with patients suffering from posttraumatic stress disorder (PTSD) revealed altered forgivability judgments following symptom resolution, suggesting that traumatic experience changes brain responses to social cognition tasks (Farrow et al. Reference Farrow, Hunter, Wilkinson, Gouneea, Fawbert, Smith, Lee, Mason, Spence and Woodruff2005). Hayashi et al. (Reference Hayashi, Abe, Ueno, Shigemune, Mori, Tashiro and Fujii2010) further observed in healthy subjects that the ventromedial prefrontal cortices (vmPFC) play a central role in forgivability judgments for moral transgressions regarding deceptive behavior.
Although game theory has clearly advanced our understanding of social decision-making (Sanfey Reference Sanfey2007), deciding upon forgiveness versus revenge is neither an all-or-nothing proposition (Hayashi et al. Reference Hayashi, Abe, Ueno, Shigemune, Mori, Tashiro and Fujii2010), nor a purely rational or computational process. Unfortunately, most psychological and neuroscientific studies have largely tried to assess forgiveness via hypothetical moral scenarios (e.g., “Which of the following crimes you would see as more forgivable?”; Farrow et al. Reference Farrow, Zheng, Wilkinson, Spence, Deakin, Tarrier, Griffiths and Woodruff2001, p. 2434) instead of via real and personally relevant stimuli. Notably, all forgiveness scenarios have been based on judging actions of unknown individuals (cf. Farrow et al. Reference Farrow, Zheng, Wilkinson, Spence, Deakin, Tarrier, Griffiths and Woodruff2001). It thus remains unclear whether activations in the proposed brain regions are specific to forgiveness or whether they mirror social and/or moral judgment more globally (Hayashi et al. Reference Hayashi, Abe, Ueno, Shigemune, Mori, Tashiro and Fujii2010).
Here, we would like to propose that an alternative, non–game-theoretic approach is also well suited for investigating the roles of both revenge and forgiveness. More specifically, we hold an autobiographical memory fMRI paradigm (for a review, see Maguire Reference Maguire2001) as particularly promising. The main benefit of using events with personal significance is that by reliving memories from the participants' own history, forgiveness- and revenge-related emotions (e.g., anger, fear) that were connected to those memories are subjectively re-experienced (Rubin Reference Rubin2005; Svoboda et al. Reference Svoboda, McKinnon and Levine2006). An ancillary advantage is that this procedure allows for the induction of a personally relevant affective state (Wagner et al. Reference Wagner, N'Diaye, Ethofer and Vuilleumier2011) and this, in turn, may activate brain regions in a similar manner as the original emotional event (Buchanan Reference Buchanan2007). We conjecture that this approach is able (a) to induce an intrapsychic instance of real-life forgiveness and revenge, and (b) to elicit affect-laden memory relevant for forgiveness and revenge.
We further believe that this approach could shed light on McCullough et al.'s pronounced suggestion that the evolved forgiveness systems “inhibit revenge” (sect. 4.2, para. 2). If so, emotional reliving of forgiveness events should recruit prefrontal brain areas robustly associated with cognitive control and emotion regulation. This proposal stands in line with recent empirical evidence, demonstrating that executive functioning (i.e., cognitive control processes) is negatively associated with retaliatory aggression, and that this effect is mediated by lower levels of revenge motivation (i.e., higher forgiveness) (Wilkowski et al. Reference Wilkowski, Robinson and Troop-Gordon2010). Relatedly, a series of studies by Pronk and colleagues have illustrated that cognitive control is positively associated with forgiveness (see Pronk et al. Reference Pronk, Karremans, Overbeek, Vermuist and Wigboldus2010). Pronk et al. (Reference Pronk, Karremans, Overbeek, Vermuist and Wigboldus2010, p. 128 f.), and even directly allude to the possibility that the prefrontal cortex (involving the anterior cingulate cortex [ACC]) may be implicated in the down-regulation of negative affect.
To conclude, from a neuroscientific perspective, it is not only important to explore which specific brain areas are involved in revenge and forgiveness processes, but also to demonstrate (a) the interplay of both cognitive and affective signature(s) within these processes; (b) the involvement of emotionally arousing memory in these processes; and (c) its advantage over game-theoretic approaches to the study of forgiveness and revenge. Using McCullough et al.'s framework as a starting point, these important issues open up fields of interesting research questions to be addressed in the future.
Mere acceptance or implicit forgiveness?
McCullough et al. propose “acceptance” as a means of tolerating the transgressor's Welfare Tradeoff Ratio (WTR; Tooby et al. Reference Tooby, Cosmides, Sell, Lieberman, Sznycer and Elliott2008). Despite establishing one plausible behavioral option to the infliction of interpersonal harm, we deem McCullough et al.'s notion elusive for two reasons:
First, it neglects the possibility that accepting an injustice may be equivalent to what Exline and Baumeister (Reference Exline, Baumeister, McCullough, Pargament and Thoresen2000) termed implicit forgiveness. Whereas explicit forgiveness (a) directly relates to an existing debt and (b) acknowledges one's willingness to absolve the transgressor from his or her guilt (e.g., “I forgive you for cheating on me”), the offended person may also implicitly express forgiveness – either by downplaying the transgression, for example, by saying “It's okay,” or wordlessly by maintaining contact with the transgressor and thus not ceasing the relationship. Along this line, the concept of implicit forgiveness differs from mere acceptance in the sense that a motivation to engage in retaliatory aggression changes into forgiving motivations, but no direct reference is made to the cancelled debt (cf. Exline & Baumeister Reference Exline, Baumeister, McCullough, Pargament and Thoresen2000). We therefore think that implicit forgiveness may also represent a possible adaptive mechanism when perceiving a social norm violation.
Second, one important question remains unanswered: What if the victim, for reasons of introspective limits (Nisbett & Wilson Reference Nisbett and Wilson1977), explicitly reports that he or she is okay with the aggressor's WTR, yet, implicitly, it reveals that he or she is still holding grudges? In order to provide empirical evidence for McCullough et al.'s suggestion that acceptance is marked by an absence of residual motivation to engage in retaliation, the use of indirect forgiveness measures seems beneficial. Consistent with the notion that cognitive accessibility of the self through introspection is limited (Greenwald & Banaji Reference Greenwald and Banaji1995; Greenwald et al. Reference Greenwald, Banaji, Rudman, Farnham, Nosek and Mellott2002), indirect measures such as the Implicit Association Test (IAT; Greenwald et al. Reference Greenwald, McGhee and Schwartz1998) capture information processing that resides outside conscious control or awareness (e.g., Asendorpf et al. Reference Asendorpf, Banse and Mücke2002; Greenwald & Banaji Reference Greenwald and Banaji1995; Wilson et al. Reference Wilson, Lindsey and Schooler2000). Hence, developing an indirect forgiveness measure could not only favor a multi-method approach (Eid & Diener Reference Eid, Diener, Eid and Diener2006), but also elucidate phenomenological differences between acceptance and implicit forgiveness.
Investigating the neural substrates of revenge and forgiveness: An fMRI approach
We concur with McCullough et al. that making adaptive decisions about revenge and forgiveness encompasses multiple cognitive components. Judging the forgivability of another's actions is one such component (Farrow et al. Reference Farrow, Zheng, Wilkinson, Spence, Deakin, Tarrier, Griffiths and Woodruff2001). For example, a post-therapy fMRI study with patients suffering from posttraumatic stress disorder (PTSD) revealed altered forgivability judgments following symptom resolution, suggesting that traumatic experience changes brain responses to social cognition tasks (Farrow et al. Reference Farrow, Hunter, Wilkinson, Gouneea, Fawbert, Smith, Lee, Mason, Spence and Woodruff2005). Hayashi et al. (Reference Hayashi, Abe, Ueno, Shigemune, Mori, Tashiro and Fujii2010) further observed in healthy subjects that the ventromedial prefrontal cortices (vmPFC) play a central role in forgivability judgments for moral transgressions regarding deceptive behavior.
Although game theory has clearly advanced our understanding of social decision-making (Sanfey Reference Sanfey2007), deciding upon forgiveness versus revenge is neither an all-or-nothing proposition (Hayashi et al. Reference Hayashi, Abe, Ueno, Shigemune, Mori, Tashiro and Fujii2010), nor a purely rational or computational process. Unfortunately, most psychological and neuroscientific studies have largely tried to assess forgiveness via hypothetical moral scenarios (e.g., “Which of the following crimes you would see as more forgivable?”; Farrow et al. Reference Farrow, Zheng, Wilkinson, Spence, Deakin, Tarrier, Griffiths and Woodruff2001, p. 2434) instead of via real and personally relevant stimuli. Notably, all forgiveness scenarios have been based on judging actions of unknown individuals (cf. Farrow et al. Reference Farrow, Zheng, Wilkinson, Spence, Deakin, Tarrier, Griffiths and Woodruff2001). It thus remains unclear whether activations in the proposed brain regions are specific to forgiveness or whether they mirror social and/or moral judgment more globally (Hayashi et al. Reference Hayashi, Abe, Ueno, Shigemune, Mori, Tashiro and Fujii2010).
Here, we would like to propose that an alternative, non–game-theoretic approach is also well suited for investigating the roles of both revenge and forgiveness. More specifically, we hold an autobiographical memory fMRI paradigm (for a review, see Maguire Reference Maguire2001) as particularly promising. The main benefit of using events with personal significance is that by reliving memories from the participants' own history, forgiveness- and revenge-related emotions (e.g., anger, fear) that were connected to those memories are subjectively re-experienced (Rubin Reference Rubin2005; Svoboda et al. Reference Svoboda, McKinnon and Levine2006). An ancillary advantage is that this procedure allows for the induction of a personally relevant affective state (Wagner et al. Reference Wagner, N'Diaye, Ethofer and Vuilleumier2011) and this, in turn, may activate brain regions in a similar manner as the original emotional event (Buchanan Reference Buchanan2007). We conjecture that this approach is able (a) to induce an intrapsychic instance of real-life forgiveness and revenge, and (b) to elicit affect-laden memory relevant for forgiveness and revenge.
We further believe that this approach could shed light on McCullough et al.'s pronounced suggestion that the evolved forgiveness systems “inhibit revenge” (sect. 4.2, para. 2). If so, emotional reliving of forgiveness events should recruit prefrontal brain areas robustly associated with cognitive control and emotion regulation. This proposal stands in line with recent empirical evidence, demonstrating that executive functioning (i.e., cognitive control processes) is negatively associated with retaliatory aggression, and that this effect is mediated by lower levels of revenge motivation (i.e., higher forgiveness) (Wilkowski et al. Reference Wilkowski, Robinson and Troop-Gordon2010). Relatedly, a series of studies by Pronk and colleagues have illustrated that cognitive control is positively associated with forgiveness (see Pronk et al. Reference Pronk, Karremans, Overbeek, Vermuist and Wigboldus2010). Pronk et al. (Reference Pronk, Karremans, Overbeek, Vermuist and Wigboldus2010, p. 128 f.), and even directly allude to the possibility that the prefrontal cortex (involving the anterior cingulate cortex [ACC]) may be implicated in the down-regulation of negative affect.
To conclude, from a neuroscientific perspective, it is not only important to explore which specific brain areas are involved in revenge and forgiveness processes, but also to demonstrate (a) the interplay of both cognitive and affective signature(s) within these processes; (b) the involvement of emotionally arousing memory in these processes; and (c) its advantage over game-theoretic approaches to the study of forgiveness and revenge. Using McCullough et al.'s framework as a starting point, these important issues open up fields of interesting research questions to be addressed in the future.