《社会心理学》课程教学资源（文献资料）Aggression——Competence-Impeding Electronic Games and Players’ Aggressive Feelings, Thoughts, and Behaviors.pdf

PERSONALITY PROCESSES AND INDIVIDUAL DIFFERENCES Competence-Impeding Electronic Games and Players’ Aggressive Feelings, Thoughts, and Behaviors Andrew K. Przybylski University of Rochester and University of Oxford Edward L. Deci University of Rochester C. Scott Rigby Immersyve, Celebration, Florida Richard M. Ryan University of Rochester Recent studies have examined whether electronic games foster aggression. At present, the extent to which games contribute to aggression and the mechanisms through which such links may exist are hotly debated points. In current research we tested a motivational hypothesis derived from self-determination theory—that gaming would be associated with indicators of human aggression to the degree that the interactive elements of games serve to impede players’ fundamental psychological need for competence. Seven studies, using multiple methods to manipulate player competence and a range of approaches for evaluating aggression, indicated that competence-impeding play led to higher levels of aggressive feelings, easier access to aggressive thoughts, and a greater likelihood of enacting aggressive behavior. Results indicated that player perceived competence was positively related to gaming motivation, a factor that was, in turn, negatively associated with player aggression. Overall, this pattern of effects was found to be independent of the presence or absence of violent game contents. We discuss the results in respect to research focused on psychological need frustration and satisfaction and as they regard gaming-related aggression literature. Keywords: motivation, competence, aggression, electronic games Philosophers and researchers alike have sought the causes of human aggression, proposing a multitude of possibilities. Diverse factors such as genetic make-up (Ferguson, 2010), social learning (Bandura, 1977), goal frustration (Miller, 1941), and ambient air temperature (Anderson, Deuser, & DeNeve, 1995) have been evaluated as potential sources of aggressive thoughts, feelings, and behaviors. More recently however, popular interest has turned to electronic game entertainment as a source of aggression. Indeed, the great majority of social science research focusing on gaming environments examines concerns that some games—violent ones in particular— have the potential to foment aggression. Despite a growing body of research, there is no clear consensus regarding the effects of gaming on aggression: Some researchers report finding consistent links between some forms of gaming and measures of aggression (e.g., Anderson & Bushman, 2001), whereas others find unreliable or inconsequential links (e.g., Elson & Ferguson, in press). Our aim in the present research was to empirically explore gaming-related aggression through the motivational lens of selfdetermination theory (SDT; Ryan & Deci, 2000)— by systematically investigating psychological need thwarting in gaming as a source of aggressive feelings, thoughts, and behaviors. Motivational Perspective SDT theorizes that human aggression and interpersonal violence result from the threatened or actual thwarting of basic psychological needs (Deci & Ryan, 2012; Ryan & Deci, 2000). SDT posits three basic psychological needs that are sensitive to supports and susceptible to impedance from environmental circumstances: The needs for competence (i.e., the experience of efficacy), autonomy (i.e., the sense of choice and volition), and relatedness (i.e., the feeling of connection and belongingness with others). When supported, these three needs form the basis of psychological health and provide the necessary and sufficient conditions for effective self-regulation. SDT researchers have argued that people are more prone to aggression when any of these three basic needs is thwarted either proximally, by situational threats or deprivations, or distally, by chronic developmental conditions (Ryan, Deci, Grolnick, & La Guardia, 2006). Several lines of research provide support for the idea that psychological need thwarting can contribute to increased aggresThis article was published Online First December 30, 2013. Andrew K. Przybylski, Department of Clinical and Social Sciences, University of Rochester, and Oxford Internet Institute, University of Oxford, Oxford, England; Edward L. Deci, Department of Clinical and Social Sciences, University of Rochester; C. Scott Rigby, Immersyve, Celebration, Florida; Richard M. Ryan, Department of Clinical and Social Sciences, University of Rochester. Correspondence concerning this article should be addressed to Andrew K. Przybylski, who is now at the Oxford Internet Institute, University of Oxford, 1 St Giles’, Oxford OX1 3JS, England. E-mail: andy.przybylski@ oii.ox.ac.uk This document is copyrighted by the American Psychological Association or one of its allied publishers. This article is intended solely for the personal use of the individual user and is not to be disseminated broadly. Journal of Personality and Social Psychology, 2014, Vol. 106, No. 3, 441– 457 © 2013 American Psychological Association 0022-3514/14/$12.00 DOI: 10.1037/a0034820 441 THIS ARTICLE HAS BEEN CORRECTED. SEE LAST PAGE

sion. Early work by Ryan and Grolnick (1986) showed that children had higher levels of implicit aggressiveness when their basic need for autonomy was impeded. More recently, Roth, KanatMaymon, and Bibi (2011) reported that classroom environments that were autonomy-need thwarting were more likely to foster bullying as well as interpersonal aggression. Weinstein, Hodgins, and Ostvik-White (2011) also showed that the salience of autonomy-blocking led to increased accessibility of aggressive thoughts, which in turn resulted in people enjoying hostile forms of humor. Neighbors, Vietor, and Knee (2002) reported that needthwarting motivation predicted experiencing pressure and egodefensiveness while driving, a shift that in turn related to aggressive driving and road rage. Weinstein (2009) showed that those situations that undermined the need for relatedness served to increase interpersonal aggression, an effect that actually carried over from a prior environment to bias social behavior and introduce aggressive feelings into a new social context. Taken together, these studies provide preliminary support for the idea that psychological need thwarting can lead to aggressiveness. To date, the effects of competence-need deprivation have not been extensively explored from an SDT perspective. The present article builds upon the prior research by systematically examining aggression as an outcome of competence-need thwarting in a novel context. Motivational Perspective and Electronic Gaming Unlike many other pursuits, most people are not typically motivated to play electronic games for extrinsic rewards such as money or fame; instead such games are pursued because they provide inherent satisfactions. Indeed, according to SDT gaming is typically intrinsically motivated and provides individuals with rich opportunities for psychological need satisfactions (Ryan, Rigby, & Przybylski, 2006). In particular, many games provide ample competence need satisfactions—feelings of efficacy and skill growth, which are fundamental to intrinsic motivation (Deci & Ryan, 1985). For example, the graded challenges and detailed, unambiguous performance feedback in computer games can support satisfaction of the need for competence. Similarly, wide-ranging opportunities for exploration and action allow for satisfaction of the need for autonomy. Finally, the affordance of communication channels and group challenges emphasizing collaboration and competition can satisfy the need for relatedness. Supporting this idea, Ryan, Rigby, and Przybylski (2006) reported on a series of experiments demonstrating how in-game need satisfactions predicted both preferences for specific games, and game enjoyment. They also demonstrated that games that were need satisfying predicted positive short-term shifts in players’ well-being. These relations were in evidence across a wide range of games, varying in content and genre. Subsequent research by Przybylski, Ryan, and Rigby (2009) examined the motivational appeal of violent game content. They reported that opportunities for aggression in electronic games were not inherently motivating or necessarily more immersive. Instead, basic need supports, for competence and autonomy in particular, accounted for the lion’s share of variability in violent game appeal and immersion. Like the earlier work of Ryan, Rigby, and Przybylski (2006), this research underscored the predictive utility of understanding games from a motivational vantage point. Przybylski et al. (2009) highlighted the extent to which games satisfied basic needs, a factor that was linked to how people engaged in games, independent of their particular contents or genres. That said, the motivation-focused approach based in SDT differs widely from how gaming-related aggression is typically studied. The Gaming-Related Aggression Literature The primary theoretical framework used to understand the links between electronic gaming and human aggression is the general aggression model (GAM; Anderson, Deuser, & DeNeve, 1995). The GAM is a social cognitive framework intended to model the paths by which exposure to violent media influences aggressive thoughts and feelings. Based on social learning theory (Bandura, 1977), the GAM argues that incidental exposure to media featuring violence is arousing and pleasurable and thus increases the future probability of intentional violent media exposure. Acute incidents of intentional self-exposure to violent media lead to chronic selfexposure. This kind of chronic exposure to violent media snowballs by increasing the accessibility of aggressive thoughts and cognitive schemas, heightening aggressive feelings, and resulting in aggressive behavior (for a comprehensive review, see Lindsay & Anderson, 2000). Originally, the GAM was designed to model the effects of violent content in traditional, passive forms of media such as comics, movies, and music. More recently however, the GAM has been used to study violence in computer games, which in contrast is an interactive domain. Broadly speaking, GAM-based studies of gaming-related aggression have been conducted using one of three approaches: correlational studies, laboratory experiments, and longitudinal designs. A number of correlational and prospective studies have demonstrated small, yet consistent links from dispositional aggression, delinquency, and poor school performance to violent game engagement (e.g., Anderson, Gentile, & Buckley, 2007). These studies have used variants of the Violent Video Game Exposure (VVGE: Anderson & Dill, 2000) questionnaire to assess violent gaming levels, which has been somewhat controversial. Researchers have highlighted serious problems with the VVGE such as suspect validity because it does not accurately tap into everyday patterns of game play and may inflate effect-size estimates (Fikkers, Valkenburg, & Vossen, 2012). Further, an increasing number of recent prospective studies have indicated that the gamingaggression link is not conclusive and is quite small when other factors are considered (Elson & Ferguson, in press). Demographic variability, parent– child relationship quality (Wallenius & Punamäki, 2008), peer deviance (Willoughby, Adachi, & Good, 2012), consistent measures of game content (Ferguson, 2011), and expert ratings of violent game exposure (e.g., von Salisch, Vogelgesang, Kristen, & Oppl, 2011) serve to moderate most observed relations between aggression and electronic gaming. Because correlational and prospective studies leave open the causal direction of the relations—that is, whether violent play makes people somewhat more aggressive or dispositionally aggressive persons seek out violent games—an increasing number of studies have sought to address this issue of causality by examining the effects of violent gaming on players’ aggressive feelings and behaviors postengagement in the laboratory. Like the crosssectional (i.e., correlational) and prospective studies, a subset of these studies have shown increased postengagement aggression for those who played violent games (e.g., Anderson & Dill, 2000; This document is copyrighted by the American Psychological Association or one of its allied publishers. This article is intended solely for the personal use of the individual user and is not to be disseminated broadly. 442 PRZYBYLSKI, DECI, RIGBY, AND RYAN

Anderson & Murphy, 2003), whereas others have not found these effects (e.g., Cicchirillo & Chory-Assad, 2005; Kirsh, 1998; McClure & Mears, 1986; Williams & Skoric, 2005). Given this active debate, a number of dueling meta-analyses have recently been published on the growing number of contradicting experiments. Like the experiments themselves, these metaanalyses directly conflict in some cases (see Anderson et al., 2010, and Ferguson & Kilburn, 2010). That said, some findings from these summaries are relevant for a motivation-focused analysis of gaming-related aggression. For example, in reviewing a decade of experiments assessing links between aggression and computer games, Ferguson (2007) reported that some of the conflicting results in the gaming-related aggression area have emerged from intervening variables specific to interactive gaming contexts and unstandardized aggression measures. Similarly, Sherry’s 2001 and 2007 meta-analyses reported evidence that a number of experimental factors present in the experimental literature, such as player arousal and the amount of experience, may differentially influence the relations between violent-game exposure and player aggression. Sherry’s findings indicated that participants assigned to short periods of exposure showed the strongest link between gaming and aggression outcomes, whereas medium and longer-term periods of experimental exposure showed null and in some cases, reverse effects. Sherry speculated that the initial minutes of playing a video game may be highly stimulating— explaining larger effects for brief game exposure— but that this arousal might plateau and regress to the mean under conditions where play continues for longer time periods. Like Ferguson (2007), Sherry (2001, 2007) argued that the patterns of results demonstrated by their metaanalyses indicated the need to use new theoretical perspectives to study the gaming-aggression link. A primary objective of the present research was to apply SDT to investigate gaming-related aggression through a motivation-based lens, extending this complex literature. As reviewed previously, SDT research examining acute and chronic impedance of the basic psychological needs for autonomy and relatedness showed that deprivation of these supports result in increased aggression. In contrast, the effects of competence need deprivation on aggressive thoughts, feelings, and behavior have not been as extensively explored from an SDT viewpoint. Computer gaming, a domain where human competence is of paramount importance, provides an excellent context for studying the effects of competence-thwarting experiences. Further, as past SDT-based gaming research indicates, competence is central to the interactive experiences that make games appealing. Competence thwarting would thus seem to serve as an ideal candidate for evaluation as a source of gamingrelated aggression. Importantly, although SDT-based gaming research has focused on how virtual contexts can support needs and bolster well-being, no empirical work has examined the negative consequences of need thwarting in gaming. Indeed, many of the positive motivational mechanisms that have been studied in terms of supporting experiences of competence also can be reviewed in terms of their potential to impede competence. For example, Ryan, Rigby, & Przybylski (2006) demonstrated that mastery-of-controls—the learned ability to effortlessly use a game’s control interface to carry out actions in virtual environments—was essential to building an overall sense of competence in engaging in game play. Mastery-of-controls played an important role in game motivation as a necessary, but not sufficient, condition for achieving psychological need satisfying play. Electronic game developers aim to minimize the complexity of game controls in an attempt to hook players’ interest and excitement but do not always succeed. Despite the best efforts of game creators, the controls and rules of computer games are often quite elaborate and require significant trial and error learning and sustained effort on the players’ part. Often this means that players require a number of gaming sessions to master the controls and understand the rules, and balance of challenges presented by a new game. This is especially the case with games intended for more experienced players because they provide more in-depth interactive experiences. Regarding balance, however, this investment eventually pays off in the players’ favor. For example, complex games can offer more immersive experiences and provide players with important gratifications such as stress reduction (Reinecke, 2009) and opportunities to explore ideal self-aspects (Przybylski, Weinstein, Murayama, Lynch, & Ryan, 2012). Games succeed commercially when they strike the balance between complexity and competence support and fail when they do not strike this balance. Games that get this balance wrong are described by critics as providing “a steep learning curve.” Competence-impeding gaming experiences have the potential to aggravate and demotivate players. SDT-based research into gaming provides evidence that the skill-graded challenges of games are potential motivators because they can provide optimal challenges. However, challenges provided by computer-controlled algorithms can also be poorly scaled to a specific player’s abilities, and they may present overly difficult challenges that result in repeated failures. This competence frustration anecdotally can lead to aggressive feelings and behaviors. For example, in multiplayer contexts where players vary widely in their skills, there is a phenomenon known to gamers as rage-quitting (Brook, 2009). Defined as the act of disconnecting gaming equipment, sometimes violently, rage-quitting is thought to result from sudden, high-intensity negative emotional experiences in response to feeling overwhelmed by competitors. Given these potential pitfalls, game designers strive to create games that attract and match players of similar skill levels and try to create algorithms that provide incremental challenges. Game developers also make extensive use of demographic and behavioral market segmentation, targeting games primarily to one of two main audiences. The first category, known as casual games, tends to offer simple challenges that cater to desires of players seeking out spontaneous gaming sessions. Hard-core games, by contrast, provide much more difficult challenges tailored to the preferences and abilities of highly skilled and invested players. By dividing games in this way, game developers aim to create optimally engaging experiences that appeal to different kinds of game players. Given the different levels of skill necessary for different games, it is possible that players will at times encounter challenges beyond their capacities, so the present research examines the competence dimensions of gaming, focusing on its effects on postgame aggressive ideation and behaviors. This approach, concerned with need thwarting, represents a shift away from focusing mainly on violent game content as a predictor of aggression. To date, the structural and motivational aspects of gaming have not been explored as a source of player aggression. Psychologically need satisfying play has been robustly linked to game This document is copyrighted by the American Psychological Association or one of its allied publishers. This article is intended solely for the personal use of the individual user and is not to be disseminated broadly. COMPETENCE IMPEDANCE AND AGGRESSION 443

engagement, immersion, and positive short-term shifts in player wellbeing (Przybylski et al., 2009; Ryan, Rigby, & Przybylski, 2006). Given this, it is plausible that need-thwarting experiences in games have the opposite effect. Specifically, gaming contexts that impede the fundamental need for competence may undermine game appeal and well-being, as well as stoke postgame aggression. By empirically evaluating this idea, our aim is to bring a new perspective to the current literature and advance understanding about the motivational sources of aggressive feelings, thoughts, and behavior. The Present Research Seven studies were conducted to explore how competencethwarting experiences of computer games influence indicators of aggression and gaming motivation. Given the active debate surrounding the links between violent content and aggression, the present work evaluated these need-thwarting hypotheses across a range of gaming contexts. We examined the effects of competence deprivation using specific designs that compared games varying in their violent content (Studies 1 and 7), that explicitly manipulated violent content (Studies 2 and 5), or that had nonviolent content (Studies 3, 4, and 6). Designing the studies in this way allowed us to disentangle game content from the motivational aspects of game structure. In Study 1, we revisited a widely cited gaming related aggression study from a motivational perspective. The original work focused on how differences between the violent contents of two computer games related to player aggression. In this study, we explored how the varied motivational features of the games used in the experiment related to short-term shifts in aggressive feelings. In Study 2, we manipulated the violent content of a single game, holding the motivational features of the game constant. Our goal was to test how players’ experiences of mastery related to aggressive feelings independent of the violent contents of the game. In Studies 3 and 4, we shifted the focus to nonviolent gaming contexts to dig deeper into the factors that shape player experiences of competence as well as influence aggressive thoughts and feelings. In both experiments, we manipulated the complexity of a puzzle game’s interface to test how this change influenced assessments of competence and aggression. First, we evaluated how complex game controls impacted the accessibility of aggressive thoughts and positivity of attitudes about the game. Second, we tested the idea that increases in aggression rooted in competence deprivation would undermine game enjoyment. In Studies 5 and 6, we examined additional mechanisms through which games might influence player competence, aggressive feelings, and aggressive behavior. In Study 5, we investigated how different levels of player experience influenced aggressive feelings as mediated by players’ felt competence, and in Study 6, we manipulated a puzzle game’s level of challenge to evaluate how competence-impedance influences players’ aggressive feelings and behavior. Finally in Study 7, we shifted from experimental methods to a field study, recruiting self-selecting computer-game players. Our aim was to test the competence-impedance hypothesis in a community sample. We evaluated how variability in player competence as well as between-game variability in violent content related to postplay aggressive feelings and gaming enjoyment. Across the seven studies, our aim was to investigate a perspective that considers the interactivity of games as a factor in the gaming-related aggression area and to clarify how some aspects of gaming robustly contribute to players’ aggressive thoughts, feelings, and behaviors. We did that by evaluating the need-thwarting hypothesis derived from SDT in the gaming domain, an area that is principally concerned with performance, interaction, and competence. Study 1 Study 1 investigated how players’ competent use of game interfaces related to gaming-related aggression. We adapted a widely cited experimental design focused on gaming and aggression (Anderson et al., 2004) that compared one violent game and one nonviolent game. Because the violent game had complex controls and the nonviolent exemplar had simpler controls, we tested the extent to which self-reported mastery-of-controls influenced shortterm increases in aggressive feelings while controlling for the game content. We predicted that those playing the violent game (with a complex interface) would report lower levels of masteryof-controls compared to those assigned to play the low-violence game, and we hypothesized that the players’ mastery-of-controls would be negatively associated with aggressive affect. Method Procedure. Ninety-nine university undergraduates (41 males) received extra course credit for participating. Questionnaires were administered before and after a 20-min game engagement period. Following the completion of the first group of questionnaires, participants were randomly assigned to play one of two target games. Demographic information was collected on the initial set of questionnaires, aggressive feelings were assessed before and after game engagement, and the players’ mastery-of-controls was measured following game engagement. Target games. Participants were randomly assigned to play one of two target games identified by Anderson et al. (2004; Study 2) as representative of violent and nonviolent games. The nonviolent exemplar, Glider Pro 4, is a single-player game, designed for relatively short play, in which players use two keyboard keys to navigate a paper airplane through a two-dimensional image of a home interior. This skill can be readily mastered by gaming novices. The violent game used in this study, Marathon 2, is a game meant for dedicated computer game players. Designed for extended gaming sessions, players must use a mouse and 20 keyboard keys to navigate combat in a three-dimensional environment. Measures. Survey measures were delivered in HTML format. All items, except for participant gender and age, used 7-point scales and utilized their scale as appropriate response anchors. Aggressive affect. The 35-item State Hostility Scale was used to assess aggressive feelings (Anderson et al., 1995). Participants rated the extent to which they agreed with each hostile mood statement at that moment: “I feel irritated,” “I feel like I am about to explode,” and “I feel friendly” (reversed). Items were reversed appropriately and averaged, creating before-play (M 2.41, SD 0.82, .97) and after-play aggressive affect scores (M 2.54, SD 0.95, .96). Because we are interested in short-term shifts in aggressive feelings from pre- to postengagement, we This document is copyrighted by the American Psychological Association or one of its allied publishers. This article is intended solely for the personal use of the individual user and is not to be disseminated broadly. 444 PRZYBYLSKI, DECI, RIGBY, AND RYAN

regressed postplay scores onto preplay scores and saved the standardized residual scores. This enabled us to quantify change in aggressive affect for each participant. Mastery-of-controls. To assess participants’ felt competence using game controls, we used an intuitive controls assessment used in previous motivation and gaming research (Ryan, Rigby, & Przybylski, 2006). Three items assessed how effortlessly participants found the control interface for carrying out their intentions in the game. Items included “The game controls are intuitive” and “When I wanted to do something in the game, it was easy to remember the corresponding control.” The scale demonstrated acceptable reliability (M 4.59, SD 1.59, .72). Results Demographics. Participants’ age and gender were collected in all seven of the present studies. Where significant differences emerged, the relations were relatively small in magnitude (average R2 .03) or were not of interest in the present inquiry; for example, females tended to have less gaming experience and lower levels of competence during play than did males. We conducted all analyses presented in this article twice, once including participant demographics as control variables and once leaving them out. The direction, magnitude, and significance levels did not vary between these parallel analyses, so we did not report the analyses including demographics to conserve space. Player competence. We hypothesized that poor mastery-ofcontrols would be associated with increased levels of aggressive feelings following game engagement when controlling for type of game and the interaction of game type and mastery-of-controls. To test this hypothesis, we regressed residualized change scores in aggressive feelings simultaneously on mastery-of-controls, (97) .33, p .001, R2 .10, and the target game type (nonviolent 1, violent 1), (97) .06, p .55. The data collected for Study 1 allowed us to evaluate the relation of players’ felt competence (i.e., mastery-of-controls) to aggression when controlling for game content (violent vs. nonviolent). We evaluated a hierarchical moderation model to test the idea that game content moderated the relation between mastery-of-controls and aggressive feelings and found the interaction term was not significant, (95) .07, p .80. We thus did not find evidence that player felt competence and game content interacted to account for additional variability in player aggression. Results from this provided initial support for the competence-impeding hypothesis: Struggling with feelings of incompetence at the game interface relates to increased levels of aggressive affect. Target game differences. We predicted that the violent game used in this classic design would present a formidable challenge to mastery-of-controls, thus impeding participants’ experiences of competence. Results obtained by regressing mastery-of-controls onto the game-condition code (nonviolent 1, high violence 1), (98) .20, p .05, R2 .04, showed the violent game presented a barrier to players’ competence in using the controls. The present study also allowed us to test a conceptual replication of the aggression effects reported by Anderson et al. (2004; Study 2). Results derived by regressing change in aggressive affect onto game condition-code did not show higher aggression for those randomly assigned to play the violent game, (98) .004, p .97. We also examined the indirect effect that game content (violent vs. nonviolent) had on players’ aggressive feelings by way of player competence. More specifically, we evaluated a mediation model in which we tested mastery-of-controls (the mediating variable in Figure 1) as an intervening factor linking game type (the independent variable) to short-term shifts in aggression (the outcome variable) following the bootstrapping approach outlined by Preacher and Hayes (2008). As noted previously, there was no total effect observed relating game type to change in aggressive feelings (path C), .08, p .41; mastery-of-controls was predicted by game type (path A), .25, p .001; and change in aggressive feelings was predicted by mastery-of-controls (path B), .32, p .001. Bootstrapping indicated a significant indirect effect (path A B). The 95% confidence interval for the indirect path, based on 10,000 resamples, ranged from 0.02 to 0.33, and it accounted for 10.61% of the variability (R2 ) in aggressive feelings. Given that the C and C= paths were nonsignificant while the A B path was significant, results indicated that being assigned to play the violent game had a positive influence on short-term shifts in aggressive feelings insofar as the more complex control interface impeded player competence. Study 2 The aim of Study 2 was to conceptually replicate Study 1 in a more elegant way. Specifically in Study 2, we carefully manipulated only the graphics and narrative conceit of a single game to have a violent version and a nonviolent version of the same game. As in Study 1, we tested the hypothesis that players who felt incompetent using the game interface would report increased levels of aggressive feelings postengagement, over and above variability attributable to violent game content. Method Procedure. One hundred one undergraduates (36 males), mean age 19.6 years (SD 1.32), received extra course credit in exchange for participating. Upon entering the lab, all participants engaged in a 20-min practice period with a version of the game created specifically for training purposes. Following this, demographic information and aggressive affect were assessed, and participants were randomly assigned to a high or low violence 20-min play period. These versions were created in order to present two levels of violence, holding constant other aspects of the game such as landscape, visual complexity, and gameplay mechanics. Target game content. We created two additional gaming environments based on the popular and commercially available game Half-Life 2 using a programmer tool kit. The first environFigure 1. Conceptual mediation model. This document is copyrighted by the American Psychological Association or one of its allied publishers. This article is intended solely for the personal use of the individual user and is not to be disseminated broadly. COMPETENCE IMPEDANCE AND AGGRESSION 445