Automatic processes and individual differences in aggressive behavior Juliette Richetin a, , Deborah South Richardson b a University of Milan-Bicocca, Italy b Augusta State University, USA a r t i c l e i n f o a b s t r a c t Article history: Received 16 July 2007 Received in revised form 27 June 2008 Accepted 27 June 2008 Available online 8 July 2008 In a context in which aggressive behavior has been predominantly predicted by self-reports, this paper considers how a theoretical and empirical examination of automatic and deliberative processes in information processing and decision making may contribute to our understanding of aggressive behavior. We review research devoted to distinguishing two types of aggression with regard to the level of automaticity or control they involve, a distinction similar to the one between automatic and deliberative processes. In parallel with this theoretical distinction, implicit measures appear to be a good candidate for measuring aggression and predicting aggressive behavior. Although consideration of automatic processes is essential for a better understanding of how and why people act aggressively, it should not lead to the conclusion that aggressive behavior is fully automatic. This contribution underlines that the interaction between environment and individual differences is the key element at the implicit level, as it is at the explicit level. Some future directions for studying aggression using implicit measures are drawn. 2008 Elsevier Ltd. All rights reserved. Keywords: Aggression Automatic processes Implicit measures Individual differences Behavior Contents 1. Two types of aggression . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 424 2. Two systems of information processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 424 3. Implicit measures: the case of the Implicit Association Test (IAT) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 425 4. The IAT for assessing aggressiveness and predicting aggressive behavior: few answers, many questions . . . . . . . . . . . . 425 5. Interaction between individual differences and situation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 426 6. The role of control in aggressive behavior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 427 7. Some future potential directions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 428 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 428 Cognitive processes are understood to play an important role in aggression. For example, several theories of aggression include cognition as a central process (e.g., Berkowitz, 1989; Zillmann, 1988) and research by Huesmann and colleagues (e.g., Huesmann, 1988; Huesmann & Guerra, 1997) has examined the role of schemas in aggressive behavior. However, little theoretical and empirical work has focused on the role of automatic processes in aggressive behavior (with the exception of Todorov & Bargh, 2002). Aggression and Violent Behavior 13 (2008) 423­430 Corresponding author. Faculty of Psychology, Universit degli studi di Milano-Bicocca, Viale dell'Innovazione, 10 (U9) 20126 Milan, Italy. Tel.: +39 02 6448 3820; fax: +39 02 6448 3788. E-mail address: juliette.richetin@unimib.it (J. Richetin). 1359-1789/$ ­ see front matter 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.avb.2008.06.005 Contents lists available at ScienceDirect Aggression and Violent Behavior The present paper will review selected research in aggression and in social cognition to develop the argument that aggression research would benefit from consideration of the role of automatic processes. This paper will first briefly review the literature on two types of aggression defined as impulsive versus thoughtful. Then, we will see that a parallel distinction could be made about these two types of aggression to the one made in social cognition between automatic and deliberative processes. We will also review different types of implicit measures issued from the research on automaticity and describe more thoroughly the most commonly used, which is the Implicit Association Test. We will see that, contrary to other recent implicit measures, the IAT has already been used to measure aggressiveness at the implicit level and more importantly, to predict aggressive behavior. Any behavior can supposedly be performed automatically if the environment primes the behavior. For instance, Aarts and Dijskerhuis (2003) showed that simply priming the concept of library made participants talk more quietly when they had a goal of visiting the library (for review, see Bargh, 2006). However, our review of empirical and theoretical work will show that this perspective is limited and that, as suggested by the interactionist view established a long time ago, the interaction between environment and individual differences is also the key at the implicit level to better prediction of any behavior, including aggression. Because we cannot talk about automaticity without referring to control processes, we will see that control mechanisms also have a moderating role on the predictive validity of implicit measures. We will finally discuss some future lines of research concerning implicit measures of aggressiveness as predictors of aggressive behavior. 1. Two types of aggression We will focus our attention on two types of aggression, one more automatic and one more controlled. The critical difference between the two types of aggression involves the level of impulsivity versus deliberation each type of aggression involves. Berkowitz (1993) made this distinction in his classification of aggression as instrumental versus hostile. His cognitiveneoassociationist model (1969, 1989, 1994) suggests that aggression would be impulsive if no higher-order cognitive processes are engaged. Caprara, Perugini, and Barbaranelli (1994) also proposed a differentiation between two types of aggression, showing the emergence of two separate factors when looking at a variety of aggression-related personality variables. One type represented the impulsive, affective dimension of aggression; the other represented the social-cognitive, instrumental dimension of aggression. Anderson and Bushman (2002), in their General Aggression Model, also distinguish between `thoughtful action' and `impulsive action.' In a similar vein, some researchers (e.g., Metcalfe & Mischel, 1999) have suggested the existence of two interrelated memory systems, the hot and cool systems, involved in the execution of aggressive behavior. The information stored in the cool system is narrative and episodic (e.g., autobiographical events) and is associated with a neutral mood. The cool system is responsible for novelty monitoring, semantic priming, problem solving, metacognition, control processes, planning, and comprehension and is important for non-impulsive and self-controlled behaviors (Metcalfe & Mischel, 1999). Responses initiated by the cool system are narrative and reflective. The hot system stores the emotionally salient aspects of events and less elaborated memories. The hot system is important for rapid automatic responses that are more inflexible, stereotyped, and affectively primary. The two systems do not directly lead to actions or responses, but rather lead to the mobilization of a response program of approach or avoidance behavior by the hot system or to the elaboration of a response program by the cool system. Moreover, the hot and cool systems work in parallel but are not independent. For example, the activation of emotional memories would activate hot nodes and lead to readiness to aggress. But the activation of facts and metacognition would lead to more self-control and less impulsive behavior. Although dichotomy between instrumental and hostile aggression has been useful for developing theories of aggression, it appears now a bit outdated (Bushman & Anderson, 2001). Indeed, it may be more useful to consider types of aggression in terms of the level of control or automaticity they require and to consider that aggressive behavior can be driven by different processes. This alternative perspective is in line with the distinction recently developed between the two types of information processing systems. 2. Two systems of information processing Much empirical and theoretical research in social cognition in the last few decades has been devoted to demonstrating the existence of two systems of information processing, one explicit and the other implicit. In the first, information processing is conscious, controlled and reflective; in the second, information is processed by unconscious, automatic and intuitive processes (e.g., Epstein, 1990; Gawronski & Bodenhausen, 2007; Greenwald & Banaji, 1995; Strack & Deutsch, 2004). Dual-process models recognize the role played by both automatic/impulsive/associative and deliberative/reflective/propositional processes as determinants of behavior (e.g., Fazio, 1990; Gawronski & Bodenhausen, 2007; Strack & Deutsch, 2004; Wilson, Lindsey, & Schooler, 2000). Although models differ concerning how automatic and deliberative processes contribute to prediction of behavior (cf., Perugini, 2005), they all distinguish these two different systems. For example, Strack and Deutsch (2004) postulate the existence of reflective and impulsive systems that activate the same behavioral schemata and operate in parallel. In the reflective system, behavior is assumed to be a consequence of a decision process, whereas in the impulsive system, behavior is a consequence of automatically spreading activation in an associative network. These two systems can interact in a synergistic or antagonistic fashion to determine behavior. The parallel between the two types of aggression we described earlier and those two systems of information processing is apparent. In fact, the behaviors that Anderson and Bushman (2002) called thoughtful and impulsive actions could be thought of as being driven by deliberative and automatic processes respectively. This distinction between automatic and deliberative systems not only has consequences at the theoretical level, causing us to consider two types of aggression involving two different 424 J. Richetin, D.S. Richardson / Aggression and Violent Behavior 13 (2008) 423­430 information processing systems; but the distinction also suggests psychometric consequences for how one measures individual differences in aggressiveness. The relatively common self-report measures straightforwardly tap into the deliberative processes; tapping into automatic processes is not so simple. Nevertheless, recent developments in implicit measures offer some possibilities. Explicit self-ratings would be considered as tapping only into the propositional processes whereas implicit measures would be considered as tapping more into the associative processes (Gawronski & Bodenhausen, 2006, 2007). 3. Implicit measures: the case of the Implicit Association Test (IAT) Several different paradigms for implicit measurement have been developed: affective priming (Fazio, Sanbonmatsu, Powell & Kardes, 1986), the Go/No go association task (Nosek & Banaji, 2001), the masked affective priming task (Frings & Wentura, 2003), the Extrinsic Affective Simon Task (EAST, De Houwer, 2003) (for reviews, see De Houwer, 2006; Fazio & Olson, 2003). The Implicit Association Test (IAT, Greenwald, McGhee, & Schwartz, 1998) is, by far, the most commonly used paradigm for implicit measures. The IAT is theoretically based on an associative network conceptualization of a Social Knowledge Structure (SKS) in memory containing a central node `me,' nodes representing other social objects, attributes of the `me' and of the other social objects, and nodes representing positive and negative valence (Greenwald, Banaji, Rudman, Farnham, Nosek, & Mellot, 2002). The self-concept is defined as the association between the concept `me' and certain attributes. The IAT self-concept is assumed to reflect the relative strength of automatic associations between the central node `me' and attribute concepts. Use of the IAT to measure self-related constructs offers two primary advantages. It provides direct access to people's attitudinal unconscious, which they are not be able to verbalize (Greenwald et al., 2002); and the IAT reveals automatic associations for those who prefer not to express those attitudes. The IAT measures indirectly the strength of the association between two contrasted target categories (e.g., self versus others) and two bipolar attribute categories (e.g., harmful versus harmless) via a computerized classification task. Participants classify randomly presented stimuli belonging to each category using two keys. The IAT score is the difference in the average response time between the two versions of the combined classification task (i.e., self­harmful and others­harmless versus self­harmless and others­harmful). The assumption underlying the IAT is that if two concepts are highly associated (e.g., self and harmful), the classification task will be easier (and the participants will respond more quickly) when the associated concepts share the same response key than when they require a different response key (for a more detailed description, see Greenwald et al., 1998). Among the diversity of applications, the IAT has been used to measure attitudes toward social groups (e.g., Dovidio, Kawakami, & Gaertner, 2002; Greenwald et al., 1998; Neumann & Seibt, 2001) as well as implicit self-concepts or personality dimensions (e.g., Asendorpf, Banse, & Mücke, 2002; Egloff & Schmukle, 2002; Schnabel, Banse, & Asendorpf, 2006; Steffens & Schulze-König, 2006; Teige, Schnabel, Banse, & Asendorpf, 2004; Ulhmann & Swanson, 2004). Numerous studies have shown the reliability of the IAT in various domains (around .80 for internal consistency and .60 for testretest stability) as well as good construct and predictive validity (e.g., Dasgupta & Greenwald, 2001; Greenwald & Farnham, 2000). Greenwald, Poehlman, Uhlmann, and Banaji's (in press) meta-analysis demonstrated the predictive validity of the IAT for different criteria such as nonverbal behaviors, impression formation, prejudice, voting, consumer behavior (e.g., Dasgupta & Greenwald, 2001; Greenwald & Farnham, 2000; Greenwald et al., in press; Richetin, Perugini, Adjali, & Hurling, 2007), as well as personality concepts such as shyness and anxiety (Asendorpf et al., 2002; Egloff & Schmukle, 2002; for a discussion on the use of implicit measures in personality, see Banse & Greenwald, 2007). Moreover the IAT appears to also have incremental validity over and above explicit measures (e.g., Egloff & Schmukle, 2002; Richetin, Perugini, Prestwich, & O'Gorman, 2007; Schnabel et al., 2006). 4. The IAT for assessing aggressiveness and predicting aggressive behavior: few answers, many questions The IAT or other implicit measures are useful for assessing aggressiveness for three primary reasons. First, as we saw before, explicit measures such as self-reports tap only into processes involved in the explicit information processing mode. Second, the IAT has been demonstrated to have incremental validity over and above explicit measures. And finally, aggressive behavior is typically socially undesirable and reports of such are therefore subject to social desirability biases, so the predictive validity of explicit measures for aggressive behavior is questionable. Implicit measures may help to improve the prediction of aggressive behavior. So far, the only recent implicit measure that has been successfully used to assess aggressiveness and predict aggressive behavior is the IAT. Therefore, the focus will be only on the IAT. The network conception of the Social Knowledge Structure as a basis of the IAT recalls Berkowitz's cognitive-neoassociationist model where negative affect becomes cognitively associated with negative thoughts, emotions and reflexive behavior. A negative experience would be linked to aggressive thoughts and/or behavior and the more this association is activated, the stronger it would become (Fazio, 1990; Ratcliff & McKoon, 1997). Banse and Fischer (2002) investigated the predictive validity of implicit and explicit measures of aggressiveness for the behavior of ice hockey players and volleyball players. They used an explicit measure of aggressiveness and two IATs with two different types of items, consisting of traits words (e.g., `provocative,' `agreeable') or interaction words (e.g., `fight' and `talk') respectively, to operationalize Aggressive versus Peaceful categories. They showed that only the IAT interaction words, but not the IAT-trait words or the explicit measure, predicted the number of matches with penalties for ice hockey and volleyball players. Gray, MacCulloch, Smith, Morris, and Snowden (2003) demonstrated by using the IAT that psychopathic murderers showed a weaker association between unpleasant and violent words (compare to the association between pleasant and peaceful words) than non-psychopathic murderers. Other studies also have demonstrated the ability of the IAT to predict aggressive behavior (Bluemke 425J. Richetin, D.S. Richardson / Aggression and Violent Behavior 13 (2008) 423­430 & Zumback, submitted for publication, 2007; Gollwitzer, Banse, Eisenbach, & Naumann, 2007). However, Schnabel et al. (2006) found that an IAT anger measure did not predict angry behavior whereas the explicit measure did. They used an IAT to connect target (me versus others) and attribute (angry versus self-controlled) categories and explicit measures to predict independent judges' ratings of videotaped participants during an anger-inducing computer crash. Taken together, these studies do not clearly establish whether IATs for aggressiveness or anger predict aggressive or angry behavior. However, they suggest that procedural details, such as the type of stimuli and category labels used for the IAT seem to have a non-negligible effect on the predictive validity of the measure. In fact, because the IAT measures the strength of associations between concepts that are stored in memory, the way the concepts are activated could have an influence on which type of association is assessed. Focusing on the attribute category, Olson and Fazio (2004) showed that a personalized IAT using `I like' versus `I don't like' as attribute category labels outperformed a traditional IAT using `Pleasant'/`Not pleasant,' arguing that the former refers to personal evaluation whereas the latter refers to normative evaluation. Gray et al.'s (2003) study in which they used the pleasant/unpleasant attribute categories might have shown results only because they compared psychopathic murderers and non-psychopathic murderers in terms of IAT performance. The predictive validity of this IAT using the pleasant/unpleasant attribute categories might be more difficult with less extreme populations. In the same vein, some studies demonstrated that activation of the self-concept increases the predictive validity of the IAT (e.g., Perugini, O'Gorman, & Prestwich, 2007). Therefore, the activation of the node `me' might be necessary to assess individual differences in aggressiveness and the IAT measure of aggressiveness would reflect the strength of the association between `me' and aggressiveness. As far as target categories are concerned, the issue is the same for category labels as for item selection. First, Banse and Fischer (2002) demonstrated that an IAT using interaction words had better predictive validity than an IAT using trait words. Second, Schnabel et al. (2006) suggested that lack of predictive validity of the IAT and its low internal consistency might have been due to inconsistency of motivational direction and valence of the stimuli. That is, automatic categorization of stimuli within the anger IAT may have been obstructed because angry versus self-control combines approach-related words (e.g. angry) with negative valence, and avoidance related words (e.g. self-control) with positive valence. Third, Banse and Fischer (2002) used aggressive and peaceful as label categories whereas Schnabel et al. (2006) used angry versus self-controlled. Therefore, the inconsistency in the results concerning the predictive validity of the IAT might be due partly to the materials used. As a consequence, one should assure that the type of items and category labels implemented in the IAT assess what one wants to test. Type of aggression also should be considered in developing an IAT. As far as explicit measures of aggression are concerned, Bettencourt, Talley, Benjamin, and Valentine (2006) noted in their meta-analysis, that the vast majority of available studies had measured physical aggression, largely ignoring other types of aggressive behavior (e.g., verbal or indirect aggression). However, given for example the differences between direct and indirect aggression (Richardson & Green, 2003), it would be wise to consider that the predictive validity of implicit measures would differ depending on the type of aggression one is attempting to predict. Richetin, Richardson, and Mason (submitted for publication) tested this hypothesis, using two different IATs varying the type of aggression to which the target category referred (direct versus indirect aggression). They included the Richardson Conflict Response Questionnaire (RCRQ, Richardson & Green, 2003) and the Buss and Perry Aggression Questionnaire (Buss & Perry, 1992) as explicit self-report measures of direct and indirect aggression as well as a behavioral measure that involved evaluation of an experimenter who had or had not delivered an insult. By introducing two versions of the IAT, they wanted to examine whether implicit and explicit measures of indirect aggression would better predict an indirect aggressive behavior than implicit and explicit measures of direct aggression would. In both versions of the IAT the target category labels were `harmful' versus `harmless' and the attribute category labels were `me' versus `not me.' The stimuli for the `harmful' category in the direct aggression IAT were verbs exemplifying direct aggression (e.g., strangle) whereas the stimuli for the indirect aggression IAT were verbs illustrating indirect aggression (e.g., discredit). Unlike other studies using the IAT that illustrated the attribute categories Me/Others with words like `I' versus `Them,' Richetin and colleagues used items to which one could identify oneself (i.e., student, female) in order to enhance the activation of the self-concept (Perugini et al., 2007). The results showed that neither of the IATs predicted indirect aggressive behavior. However, an interaction effect between the IAT-direct aggression and the experimental manipulation was obtained: The IAT-direct aggression predicted the behavioral criteria when participants were provoked; it did not predict when participants were not provoked. The authors explained the lack of effects for the indirect aggression IAT as a result of the higher impact of the direct aggression items. The indirect items may be less clearly associated with aggressiveness and in consequence less salient in the association between the self-concept and aggression. Richetin et al.'s (submitted for publication) results provide some new insights about the validity of the IAT for predicting aggressive behavior. They found that the IAT-direct aggression predicted aggressive behavior but only when individuals had been provoked. In sum, they showed a moderation effect of the context of provocation for the predictive validity of implicit measures. 5. Interaction between individual differences and situation Measures of aggression, whether explicit or implicit, aim to assess individual differences. However, these measures do not always predict aggressive behavior. The situation in which the behavior is performed is also a key in the prediction. Numerous studies have examined the moderating role of the situation in the predictive validity of explicit measures of individual differences in aggressiveness. For example in a meta-analysis of 63 studies, Bettencourt et al. (2006) showed that trait aggressiveness and trait irritability influenced aggressive behavior under both provoking and neutral conditions but that other personality variables, such as trait anger, type A personality and dissipation­rumination, influenced aggressive behavior only 426 J. Richetin, D.S. Richardson / Aggression and Violent Behavior 13 (2008) 423­430 under provoking conditions. For example, studies showed that the predictive validity of self-report measures of aggression (e.g., Giancola & Zeichner, 1995; Hammock & Richardson, 1992) was even stronger when the confederate angered the participants or when participants watched a violent videotape (Bushman,1995). This work on explicit measures of aggression has contributed to a better understanding of why some people act aggressively whereas others do not, and why some people react aggressively in some situations and not in others. In other words, at the explicit level, measures of individual differences in aggression have better predictive power when the situation elicits an aggressive response. Conclusions as to implicit measures are less clear. Since Higgins, Rholes, and Jones (1977), numerous studies have shown that the unconscious activation of psychological concepts (e.g., trait inferences, stereotypes, goals) via subliminal or supraliminal priming can lead directly to behavior (for reviews, see Dijksterhuis & Bargh, 2001; Higgins, 1996). For example, if one is primed with the concept "rude," the likelihood of behaving rudely is increased because the concept is temporarily accessible and triggers relevant cognitive activities that lead to behavior without need for conscious or deliberative decision making (cf. Bargh, Chen, & Burrows, 1996). The auto-motive model (Bargh, 1990) theorizes this often automatic and direct perceptionbehavior path by postulating that behavior is a consequence of relevant cognitive activities that can be induced by internal (intentional) or external (automatic) sources (such as priming) that in turn activate behavior. Thus, according to the auto-motive model, if one is primed by an aggressive concept via subliminal priming or via a provocation, one will automatically act aggressively. Indeed, it has been already shown that "aggressive" primes activate aggressive concepts that make violence more salient to individuals (Langley, O'Neal, Craig, & Yost, 1992). In their review, Todorov and Bargh (2002) provided extensive support for this model. However, some findings have challenged this `all automatic' conception. Cesario, Plaks, and Higgins (2006) demonstrated in three studies that a perception (e.g., via priming manipulation) will activate the relevant behavior only if the personal motivation is consistent with such behavior. Closer to our concerns, Smeesters, Warlop, Van Avermaet, Corneille, and Yzerbyt (2003) showed that a prime will vary in its effect on cooperative behavior depending on individual differences in social value orientation. Specifically, they showed that priming a picture of a priest enhanced cooperative behavior for people who scored high in pro-social orientation whereas it reduced cooperation among people who scored high in pro-self-orientation. From a broader perspective, Perugini and Prestwich (2007) suggested that the auto-motive model fails to consider the role of individual differences in the perception-behavior link and proposed the gatekeeper model in which, as in the auto-motive model, a primed concept will activate fast cognitive activities but that individual differences relevant to these cognitive activities are assumed to be key in determining whether and what behavior will follow. In other words, perception can trigger action automatically only if there is a link between the two in memory at the individual level. This assumption implies that priming can increase (assimilation) or decrease (contrast) the likelihood of performing a congruent action depending on the direction of the idiosyncratic association between the two. For example, if the link between provocation and aggressive behavior exists and is strong, the aggressive prime will lead automatically to aggressive behavior. But if the link is weak or nonexistent, the aggressive prime will not lead to an aggressive behavior or will lead to a pro-social behavior. In sum, the gatekeeper model argues that individual differences moderate the effect of priming on behavior. Perugini and Prestwich (2007) provided support for this argument by showing that a more positive implicit attitude towards Americans on the part of English participants predicted a more positive evaluation of an essay in which the spelling of some words indicated that it was written by an American (e.g., behavior instead of behaviour), but only when the American concept had been primed. Other similar results (Perugini & Prestwich, 2007) support this model. In a similar vein, Gawronski and Bodenhausen (2006) suggested that arousal should enhance automatic associations (and IAT effects) because an increase of arousal enhances dominant responses (Zajonc, 1965) and automatic associations reflect a dominant response (e.g., Lambert et al., 2003). Florack, Scarabis, and Bless (2001) showed that the IAT predicted Germans' judgments of the guilt of a Turkish criminal defendant when participants were made to feel threatened whereas the IAT did not predict when participants were not threatened. Although not directly measuring aggressive behavior, those judgments of guilt might be considered as aggressive given their potentially harmful consequences for the defendant. From the perspective of the gatekeeper model, the threat acted as a prime that activated individual differences in aggression at the implicit level. In the condition of no threat, there was no such a prime, so the individual differences in aggression were not activated. The results obtained by Richetin, Richardson, and Mason (submitted for publication) also supported this hypothesis: the IAT-direct aggression predicted an aggressive behavior only for participants who had been provoked. In other words, as for the explicit measures, the predictive power of the implicit measures is greater when the situation elicits individual differences in aggressiveness. The logic underlying the gatekeeper model is, to some extent, similar to the first level of Berkowitz's (1969,1989,1994) cognitiveneoassociationist model. Indeed, Berkowitz postulates that the association between negative experience and aggressive thoughts will lead to aggressive behavior only when the association is sufficiently strong. According to this argument, unthinking or impulsive aggression is most likely to occur when people are engaged in routine activities without a conscious monitor over thoughts or actions; if higher-order cognitive processes are activated, these aggression-related tendencies are modified and controlled. 6. The role of control in aggressive behavior Although our discussion so far has focused on automatic processes, we should also briefly consider the issue of control. Given diversity of results and theoretical positions and the lack of consistent results, we do not have space here to examine the issue of when control can occur. Rather, we will focus our attention on the effects of control or, more specifically the effects of a lack of control, on the predictive validity of implicit measures. 427J. Richetin, D.S. Richardson / Aggression and Violent Behavior 13 (2008) 423­430 Research suggests that control mechanisms are activated with self-awareness and attention to what one is thinking, feeling, and doing (Mischel, Cantor, & Feldman,1996). Tangney, Baumeister, and Boone (2004) defined control as the "ability to override or change one's inner responses, as well as to interrupt undesired behavioral tendencies and refrain from acting on them" (p. 275). In other words, control processes are viewed as different from deliberative processes in the sense that they enter into play to interrupt deliberative processes or override impulsive ones. Therefore, if individuals are not able to activate control processes because they do not have the motivation to do so or because their cognitive resources are not sufficient, they are more likely to act according to their behavioral tendencies or automatic associations. Hofmann, Rauch, and Gawronski (2007) showed that when self-regulation resources were high, candy consumption was uniquely related to dietary restraint standards; when self-regulation resources were low, candy consumption was predicted by automatic candy attitudes. As we suggested previously, the behavioral impact of automatic attitudes depends on available control resources. Experimental studies have consistently demonstrated that individuals who have consumed alcohol behave more aggressively or respond more strongly to provocation than do persons who consume nonalcoholic drinks (e.g., Giancola & Zeichner,1995; Ito, Miller, & Pollock, 1996; MacDonald, Zanna, & Holmes, 2000; Richardson, 1981). The effects of alcohol, as well as the effects of stress (e.g., Hennessy & Wiesenthal, 1999), result in a decrease of the ability to control aggression. Stucke and Baumeister (2006) showed that people who had reduced resources of self-control because they have been ask to self-regulate themselves in a previous task (i.e., situation of ego-depletion) responded more aggressively to a provocation than people who were not in an ego-depletion situation. This difference did not occur under when there was no provocation and the effect of ego-depletion was even stronger for people who were low in self-control (DeWall, Baumeister, Stillman, & Gailliot, 2007).We could thus hypothesize that implicit aggression would show a stronger relationship with aggressive behavior under conditions of no control than under conditions of strong control. 7. Some future potential directions We have raised several issues that could constitute good starting points for future research. First, given the small number of studies on implicit aggressiveness, it will be necessary to conduct additional studies to establish whether the IAT is able to predict aggressive behavior. Particular attention should be devoted to examining type of categories and category labels used to exemplify aggression. It also could be useful to employ other implicit measures such as the Go/No go task (Nosek & Banaji, 2001) that allow an approach/avoidance perspective to see whether they assess the same construct and predict the same kind of behavior that the IAT did. Some additional empirical and theoretical work is also required for a better understanding of the relation between individual differences in aggressiveness and environmental inputs at the implicit level. There is also a need for more empirical work on the predictive validity of implicit measures for different types of aggression (verbal, physical, direct, indirect). For example, it could be very informative to conduct research on how explicit and implicit measures of direct versus indirect aggression are related to incidental versus controlled aggressive behaviors. Even more interestingly, some types of aggression (e.g., reactive aggression) might be considered as more automatic or incidental than deliberative, and they could benefit from the use of implicit measures. Although self-report measures have been successfully used to assess reactive aggression (e.g., Barker, Tremblay, & Nagin, 2006; McAuliffe, Hubbard, & Rubin, 2006), one could suggest that implicit measures would assess and predict it even better. Indeed, automatic and deliberative aggression differ in the sense that these constructs are respectively determined more by automatic and deliberative processes and therefore that implicit and explicit measures respectively would assess them better. Aggression scholars disagree about the intention of harm-doing behavior (Tedeschi & Felson, 1994). Such behavior may be intended to hurt the target, to control the target, or to get one's own way. In fact, aggressive behavior can be driven by automatic processes and, as a consequence, the intention of harming could be activated without any consciousness. Moreover, explicit intentions may or may not be consistent with implicit intentions. Could implicit and explicit intentions in the same situation differ from one another? For example, when Amanda gossips about the love life of her friend, Aimee, she might explicitly intend to express concern about her friend's life; she might implicitly wish to discredit Aimee in the opinions of their social group members. If we asked Amanda why she gossiped about Aimee, she would report pro-social motivation. Perhaps an implicit measure would reveal an association of self with intention to harm. 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