Reading the Behavior Signature: Predicting Leader Personality from Individual and Group Actions Paul J. Sticha1, Elise A. Weaver1, Joseph A. Tatman2, Suzanne M. Mahoney2, and Dennis M. Buede2 1 Human Resources Research Organization (HumRRO) 66 Canal Center Plaza, Suite 400, Alexandria, VA 22314 2 Innovative Decisions, Inc. (IDI) 1945 Old Gallows Rd, Suite 207, Vienna, VA 22182 {psticha | eweaver}@humrro.org, {jatatman | smahoney | dbuede}@innovativedecisions.com Abstract1 correctly (Kelley 1967), with limited information and when outcomes are negative, people tend to attribute their own behavior to situational constraints but the behavior of others to personality (Jones and Nisbett 1971; Choi and Nisbett 1998; Malle 2006). Because individuals underestimate the impact of situational demands when inferring personality from behavior, i.e. they fall prey to the fundamental attribution error (Ross 1977), analysts wanting to understand a leader’s personality face a difficult task. This task is often further complicated by the need to infer leader personality indirectly from group behavior. The interaction among, situational variables, personal characteristics, and leader action suggests the need for two modeling tools: (a) a diagnostic tool that aids inferences about leader characteristics based on leader and group actions and the situational context in which they occur, and (b) a predictive tool that uses inferred leader characteristics to estimate the likelihood of future actions. The second of these tools was developed by Sticha, Buede, and Rees (2005; 2006), who used Bayesian networks to predict leader actions, based on personality and situational variables. This paper focuses on the diagnostic component. The overall goal of the effort was to develop a method to infer the personality of a leader from information about leader and group actions and about the situational context in which these actions occur. A number of scholars (Mecham 2006; Post, Ruby, and Shaw 2002a; 2002b) regard a radical group’s use of violence as a strategic choice, subject to leader personality traits, interpretive tendencies, and behavioral proclivities, i.e. the “behavior signature,” along with group and situational factors. To provide a testbed for model development, we focused on those leader characteristics related to group violence. The personality of a leader can be used to predict that leader’s actions as well as those of the group that he or she leads. However, except for a small number of well-known leaders, the personality of leaders must be inferred from actions and other evidence. We have developed a Bayesian network to infer leader personality variables related to violence from evidence of leader and group actions and the situational demands and context in which the actions occur. The network was applied to a historical situation, and its ability to distinguish extreme personalities was established. Introduction The term “behavior signature” describes the behavioral consistency of an individual, group, organization, society, or nation-state. In the case of a group leader, the behavior signature facilitates the analysis of intelligence data to identify and interpret indicators of leader characteristics and behaviors. Derived from information about the leader, the signatures could be used to describe the leader’s methods of operation and to predict the actions that the leader and the group that he or she leads might take. A leader’s traits, tendencies, and proclivities making up his or her personality are an important determiner of the behavior signature. These personal tendencies interact with the leader’s knowledge and experience and with the specific demands of the situation to determine what actions will be taken in a particular circumstance. While personal characteristics are well understood for a small number of well-known national leaders, they must be inferred for the vast majority of leaders, including leaders of terrorist cells, adversary military commanders, and leaders of local organizations or allied forces. Because of the complex relationship between personal characteristics, situational demand, and leader action, it is difficult to attribute a particular leader action to personal or situational causes. Although people often make these attributions Model Description A Bayesian network (Pearl 1988) is a graphical representation of relationships among a set of random variables. Probability distributions associated with each random variable augment the graph. An inference algorithm uses these distributions to calculate revised Approved for public release; distribution is unlimited. 88ABW-20080524. Copyright © 2009, Association for the Advancement of Artificial Intelligence (www.aaai.org). All rights reserved. 130 beliefs about the random variables given evidence about some of them. knowing the state of Situation d-separates Situation Report from Behavior. Finally, complete lack of knowledge about a variable dseparates the variables upon which it depends. For example, in Figure 1, not knowing anything about Behavior or Observation of Talking d-separates Situation from Personality. However, when we observe the behavior of the individual, the variables Situation and Personality become dependent. These restrictions on inference in Bayesian networks correspond to common-sense inference rules. For example, knowing the situation does not give information about an individual’s personality, while observing behavior does. However, knowledge of both behavior and situation allows a more precise and accurate estimate of personality. We were interested in modeling situations in which a leader’s personality could be indicated by the actions of the group that he or she leads. Previous research indicates that a variety of variables are associated with group risk for violence (Post, Ruby, and Shaw 2002a; 2002b). We wanted to model the variables that affect group action, including triggering events, the situational context, culture and group type, as well as the leader action. Figure 2 shows a model structure incorporating both multiple situational variables and group actions. The model shows that group action probabilities depend on the leader action and the group characteristics or type. Knowing the group type does not provide information about the leader action (or personality) unless something is known about the group action. The triggering event, culture, and immediate context are all types of situational variables, so the change from the basic model merely increases the specificity with which these variables are represented. Structure of the Model The Bayesian network in Figure 1 gives a simplified view of the relationship between the situation, personality, and behavior. This network shows that behavior is determined jointly by personality and the situation. Both the situation and behavior may be observed, but the personality must be inferred from other variables. Situation Situation Report Personality Behavior Observations of Talking Figure 1. Basic personality and behavior model. For example, we might want to know whether an individual is an introvert or an extravert. In general, we expect an extravert to talk with others more often than an introvert does. However, the situation makes a difference in an individual’s gregarious behavior. In some situations, such as at a party, we expect to observe most people talking with others. In other situations, such as in a library, we expect to observe most people behaving quietly. In both situations, we expect to observe an introvert talking less frequently than an extravert. The combination of situational demands and the individual’s personality cause the individual to behave in a particular way. We learn about the situation and behavior through observations or reports. Given such information, we can make inferences about the individual’s personality. Note that in Figure 1, we created nodes specifically to record observations of behavior and reports of the situation. Since observations or reports are not always accurate, we include these nodes to capture our uncertainty about the information in the reports. In general, inference flows both with and against the directions of the arrows in a Bayesian network. However, there are specific limits to the flow of inference in a Bayesian network. This limits are characterized by a property called d-separation (Pearl 1988), which can occur in three ways. First, if three variables are linked together in a chain, then certain knowledge regarding the intermediate variable halts the flow of information from one end of the chain to the other end (unless there is another path connecting these variables). For example, in Figure 1, certain knowledge of Behavior halts the flow of inference between the variables Situation and Observations of Talking. Second, knowledge of a variable d-separates the other variables that depend on it. For example, in Figure 1, Triggering Event Leader Personality Culture Leader Action Immediate Context Group Action Group Type Figure 2. Personality and behavior model showing situational and group variables. Representing Personality Traits In earlier work (Sticha, Buede, and Rees 2005; 2006), we developed a Bayesian network representing personality that could be used to predict leader behavior. The personality variables used in this model were drawn from the Five Factor Model (Costa and McCrae 1992), one of the dominant models in personality psychology, and a set of traits specifically developed to characterize political leaders (Hermann 1980). The model was subsequently modified, using a wider variety of personality variables, incorporating the judgments of over 40 prominent 131 leadership researchers, and employing a formal statistical analysis to provide model parameters (Sticha et al. 2008). The modified network was further revised to reverse arrow directions to make it consistent with the general model structure shown in Figure 2. The resulting personality network is shown in Figure 3. The variables in the left column represent general personality variables derived from the judgments of the leadership researchers. Correlations between these variables are represented by the two variables named DAF Factor and SAS Factor. The variables in the right column represent classes of leader actions, with the correlations between these action categories represented by the variables LF1 and LF2. The links between the columns represent the relationship between personality and action categories. For example, leaders who are high in Drive are more likely to engage in actions that initiate change and require follow through. Similarly, leaders who have a high Power Motive are less likely to act with integrity and have a more conflictual style for managing conflict. .878 Drive 6.19 Very Low 23.8 Low 39.9 Average 24.0 High Very High 6.12 50 ± 11 Follow Through 5.89 Very Low 23.9 Low 40.3 Average 24.0 High Very High 5.97 50 ± 11 .18 .17 .915 Risk and Adjustment 6.17 Very Low 24.1 Low 39.6 Average 24.0 High Very High 6.12 50 ± 11 .782 .539 SAS Factor .95 .836 Flexibility 6.09 Very Low 24.0 Low 40.0 Average 23.7 High Very High 6.15 50 ± 11 Social Responsibility 5.92 Very Low 24.0 Low 40.4 Average 23.7 High Very High 5.92 50 ± 11 Power Motive 5.23 Very Low 24.1 Low 41.2 Average 24.2 High Very High 5.30 50 ± 11 Affiliation Motive 6.03 Very Low 24.1 Low 40.0 Average 23.9 High Very High 6.06 50 ± 11 Social Perceptiveness 6.15 Very Low 24.0 Low 39.9 Average 23.9 High Very High 6.09 50 ± 11 .716 LF1 Initiate Change 6.86 Very Low 23.9 Low 38.4 Average 24.0 High Very High 6.85 50 ± 11 .26 DAF Factor .863 of the model. Each node represents a leader characteristic or personality trait. Currently, we can only make inferences about two characteristics, a leader’s affiliation motive and social responsibility, because these two variables are correlated with violent action. Including a wider range of leader or group behaviors in the model would support inferences about a greater number of personality variables. The acts component of the model consists of the violence of the leader recommended action and of the group action. The violence of the leader action is influenced by the situational demand for violence and the leader propensity to violence. The violence of the group action is influenced by the violence of leader action, leader power, and the group’s threat of violence. The links component consists of variables that link personality to action. The main linking variables in the model are the leader’s propensity to violence and social dominance orientation. The leader’s propensity to violence is a function of experience with violence. In addition, propensity to violence and social dominance orientation are functions of the personality characteristics of affiliation motive and social responsibility. These linking variables need to be modeled anew with each action scenario, while the personality component is stable. On the bottom right of the model is the group threat of violence component, a variable that is a function of a group’s readiness and propensity for violence. For a nonviolent group to engage in violence, the leader must both be recommending violence and have power over the group. Each of these requirements indicates something about the leader’s personality. Finally, the model includes a situational demand component. This variable, representing multiple pressures for violence, influences the violence of the action recommended by the leader and taken by the group. It has the strongest influence on a group’s actions when the leader is low in power. Situational demand for violence is made up of four predictors: (a) trigger demand for violence, a measure of the extent to which past and recent events might trigger a violent response; (b) expected value of violence, a costbenefit planner’s view of the likely outcome of a violent act (e.g., future funding and other support may be enhanced by a successful strike or lost with a failed one); (c) the culture’s history of violence; and (d) the violence of the local context. Each of these pressures is felt by both the leader and the group members. The model shown in Figure 4 includes the five components and variables described above and the more specific indicators that an analyst would provide. Resourcefulness 6.39 Very Low 24.0 Low 39.4 Average 23.8 High Very High 6.35 50 ± 11 .31 .36 -.17 Act with Integrity 6.28 Very Low 24.0 Low 39.5 Average 24.0 High Very High 6.26 50 ± 11 .725 .799 .677 LF2 -.05 .3 .03 .19 Manage Conflict 6.48 Very Low 23.9 Low 39.3 Average 23.9 High Very High 6.50 50 ± 11 .833 .868 Consult with Others 6.43 Very Low 23.9 Low 39.4 Average 23.8 High Very High 6.39 50 ± 11 Figure 3. Bayesian network representing personality variables. Estimating Model Conditional Probabilities Details of the Personality Prediction Model We used the following strategies to estimate conditional probability tables to link model variables, depending on the source and quality of the information on which the conditional probabilities were based. (a) In some cases (e.g., in interpreting the results of Post et al., 2002a, b), relationships were estimated by subject-matter experts The structure of the prediction model can be seen in Figure 4. On the left is the personality component of the model with the same variables that are in Figure 3. Since the goal of behavioral signature modeling is to make inferences to personality, the variables in this component are the output 132 Situational Demand Perceived Benefit due to Success of Viole... Perceived Benefit due to Success of Pe... 4.56 24.1 42.6 24.1 4.56 Very Low Benefit Low Benefit Moderate Benefit High Benefit Very High Benefit 4.56 24.1 42.6 24.1 4.56 Very Low Benefit Low Benefit Moderate Benefit High Benefit Very High Benefit 50 ± 10 Personality Variables 50 ± 10 Perceived Loss due to Failure of Pe... Perceived Loss due to Failure of Viole... Drive .878 Very Low Low Average High Very High 6.30 24.0 39.0 24.2 6.52 Perceived Likelihood of Success of Viole... Follow Through .18 Very Low Low Average High Very High 50.1 ± 11 5.91 23.9 40.1 24.2 5.84 Expected Value of Violent Solut... 20.0 20.0 20.0 20.0 20.0 Very Low Low Moderate High Very High Historical Culture of Violen... 50 ± 10 50 ± 10 Leader Tendency 4.56 24.1 42.6 24.1 4.56 Very Low Loss Low Loss Moderate Loss High Loss Very High Loss 4.56 24.1 42.6 24.1 4.56 Very Low Loss Low Loss Moderate Loss High Loss Very High Loss 0.5 ± 0.29 Expected Value of Peaceful Solut... 6.45 28.3 30.7 28.1 6.55 Very Low Low Moderate High Very High 50 ± 22 20.0 20.0 20.0 20.0 20.0 Very Low Low Moderate High Very High 50 ± 22 0.4 0.5 ± 0.29 .716 50 ± 11 .50 Notional Risk and Adjustment .915 6.75 23.3 38.6 24.9 6.47 Initiate Change .26 50.1 ± 11 Very Low Low Average High Very High Current Communal Conflict .50 Notional 6.94 23.7 38.2 24.2 7.05 Recent Triggering Event Violen... .725 LF1 Relative Expected Value of Viole... 5.34 24.0 41.1 24.2 5.34 Very Low Low Moderate High Very High Very_Low Low Moderate High Very_High 50.1 ± 11 50 ± 11 Cultural Demand for Violen... 2.37 25.1 46.4 23.6 2.43 Very Low Low Moderate High Very High 4.56 24.1 42.6 24.1 4.56 Very Low Low Moderate High Very High 49.7 ± 18 Flexibility Very Low Low Average High Very High 6.01 24.4 40.3 23.3 5.99 49.9 ± 11 Very Low Low Average High Very High 6.20 23.6 39.8 24.1 6.26 Past Triggering Event Violen... .782 5.73 23.4 40.1 24.2 6.50 50.3 ± 11 Power Motive .539 Very Low Low Average High Very High 5.31 24.0 41.1 24.2 5.31 50.1 ± 11 Affiliation Motive .95 Very Low Low Average High Very High 5.79 24.9 39.3 23.9 6.11 50 ± 11 Social Perceptiveness .836 Very Low Low Average High Very High 6.01 24.4 40.3 23.3 5.91 0.4 4.56 24.1 42.6 24.1 4.56 .35 Violence of Context 4.56 24.1 42.6 24.1 4.56 Very Low Low Moderate High Very High .08 49.8 ± 13 5.54 24.1 40.7 24.1 5.52 Attacks by Ideological Oppone... Very Low Low Moderate High Very High 0.4 Situational Demand for Viole... .34.34 10.8 23.8 32.1 23.0 10.3 Very Peaceful Peaceful Neutral Violent Very Violent 50 ± 10 Supporter Pressure for Violen... Very Low Low Moderate High Very High 50 ± 11 .51 Trigger Demand for Viole... Very Low Low Moderate High Very High 50.2 ± 10 0.4 5.00 24.2 41.6 24.2 5.05 Very Low Low Moderate High Very High 0.4 50 ± 10 4.94 24.1 41.8 24.2 4.98 50 ± 10 Successful Violence by Similar Gro... 50 ± 10 Pro-social Leadership .36 -.17 .35 6.18 23.7 39.5 24.3 6.36 Very Low Low Average High Very High .67 to .33 - .23 Leader Propensity for Viole... 50.1 ± 11 Very Low Low Moderate High Very High .677 5.90 24.2 39.8 24.2 5.84 Violence of Leader Recommended Act... Very Peaceful Peaceful Neutral Violent Very Violent .55 50 ± 11 6.92 24.4 38.0 24.0 6.70 Violence of Group Action Very Peaceful 10.7 Peaceful 23.5 Neutral 32.0 Violent 23.1 Very Violent 10.6 .33 to .67 49.9 ± 11 Group Risk 49.9 ± 13 Manage Conflict -.05 50 ± 11 SAS Factor 4.78 23.8 41.7 24.6 5.16 Very Low Low Moderate High Very High 4.94 24.1 41.7 24.3 5.05 50 ± 10 0.6 .799 Social Responsibility Very Low Low Average High Very High Poli, Econ, and Soc Instabi... Very Low Low Moderate High Very High 0.6 0.6 Resourcefulness .31 5.44 24.5 41.1 23.7 5.29 49.9 ± 11 50 ± 10 DAF Factor .863 4.94 24.0 41.7 24.3 5.05 50.1 ± 10 .17 Very Low Low Average High Very High Very Low Low Moderate High Very High Perceived Likelihood of Success of Pe... 6.51 28.2 30.6 28.3 6.46 Very Low Low Moderate High Very High .3 0.6 6.35 23.7 39.8 23.7 6.39 Very Low Low Average High Very High .833 LF2 - .26 .33 Acts Leader Experience with Viol... 6.14 24.3 39.4 24.1 5.99 Very Low Low Moderate High Very High 50 ± 11 Threat of Violence from Gro... 49.9 ± 11 Consult with Others .03 .19 Very Low Low Average High Very High Perceived Threat and Opponent Dehumani... 6.29 23.8 39.6 23.7 6.58 Very Low Low Moderate High Very High Very Low Low Moderate High Very High 6.03 24.1 39.7 24.1 6.11 49.9 ± 11 .50 Notional - .24 0.4 Very Low Low Moderate High Very High Very Low Low Moderate High Very High 50 ± 11 0.6 Very Low Low Moderate High Very High 0.6 5.37 24.1 40.7 24.2 5.54 50 ± 11 0.6 0.6 Formal Power Very Low Low Moderate High Very High 0.6 Group Pressure to be Viole... 4.56 24.1 42.6 24.1 4.56 50 ± 10 5.32 23.5 41.1 24.6 5.50 50.1 ± 11 0.6 .50 Notional 5.84 24.2 39.9 24.2 5.79 Group Experience with Viole... Very Low Low Moderate High Very High Group Propensity for Violen... 4.56 24.1 42.6 24.1 4.56 50 ± 10 Social Dominance Orientati... 4.84 23.8 41.6 24.6 5.15 50.1 ± 10 0.6 Group Readiness for Violen... Leader Power Very Low Low Moderate High Very High 9.06e-5 ± 0.081 - .24 .85 .21 50 ± 11 Very Low Low Moderate High Very High 50.1 ± 11 .868 6.34 23.8 39.5 24.0 6.33 5.26 23.9 41.1 24.3 5.47 Very Low Low Moderate High Very High 50.1 ± 11 Group Pressure to Conform Internal Capability 4.56 24.1 42.6 24.1 4.56 Very Low Low Moderate High Very High 50 ± 10 5.51 23.9 41.0 24.2 5.40 50 ± 11 External Support Very Low Low Moderate High Very High 5.71 25.1 40.8 23.2 5.20 49.7 ± 11 Violence of Group Ideol... Very Low Low Moderate High Very High 5.43 23.8 40.9 24.4 5.45 50.1 ± 11 Organizational Incentives for Viole... 5.51 24.2 41.2 23.8 5.31 Very Low Low Moderate High Very High 49.9 ± 11 Links Figure 4. Final personality inference model. using broad categories, such as low, medium, and high. In these cases, we assigned correlations to these categories, and used the correlations to estimate the conditional probability table. (b) When we could not find research that linked model variables, we were sometimes able to infer the correlations from their relationships with common mediating variables. In these cases, we represented the known correlations in a Bayesian network and generated cases of the model variables that we then used to estimate the correlation between model variables. (c) For some variables, there were no known correlations between parents and children, so we needed to elicit expert judgments to determine them. First, we developed plausible cases using our own estimates of intercorrelations among the parent variables. Then, we conducted a judgment analysis with an expert to determine appropriate relative weights for each of the parent variables in determining the value of the child variable. (d) Finally, we created latent variables to absorb common variance in correlated parent variables. The latent variables were developed using a factor analysis or structural equation model based on intercorrelations among the parent variables. for control of Gaza in June 2007. The partial timeline in Table 1 describes the five key events in this battle that were represented in the cases. Information about the cases was obtained from open source historical record. We estimated values for the model parameters from this record and reviewed our assessments with an expert who was familiar with the events. These cases provided information for the model to incorporate to learn personality variables. Table 1. Summary Timeline for Hamas Takeover of Gaza Strip Feb 8, 2007 Palestinian rivals meeting in the Islamic holy city of Mecca, Saudi Arabia reach an accord ensuring a ceasefire and unity government. Haniyeh sworn in as Prime Minister of new government. However, isolated incidents continued through March and April 2007. More than 90 people were killed in these first months. May 19, Vicious circle of killings and revenge killings 2007 intensifies, resulting in ceasefire. Some violence continues. Jun 9, 2007 Ceasefire ends, substantial clashes and revenge killings between Fatah and Hamas begin. Jun 12, Hamas launches full-scale attack after RPG attack 2007 on Haniyeh’s house, laying siege to the Fatahdominated security services, attempting decisive victory. Hamas has likely made the decision at this point to takeover Gaza. Jun 24, Conciliatory speech, efforts to rally Palestinians 2007 A Sample Application of the Model In order to test the model with real data, we built five cases based on the history of the battle between Hamas and Fatah 133 The results of executing this process are shown in Figure 5. Incorporating evidence that the leader’s experience with violence is very high lowers the expected value of both Affiliation Motive and Social Responsibility from their prior means of 50 to the 44-45 range, a drop of approximately one half of the standard deviation of the prior distribution, which was set to 10. The two ceasefire actions come next. Incorporating these actions raises the expected value of both personality variables to reflect the fact that these are peaceful actions taken in a violent environment. The curves now bend down as evidence from the breaking of the ceasefire and the decision to takeover the Gaza Strip is incorporated. Finally, the conciliatory speech given by Haniyeh (the Hamas leader) to rally all Palestinians raises the expected value of the prosocial personality variables slightly. Remember that these curves are cumulative. Each new case adds evidence to the evidence from all previous cases read into the model. Note that the two personality variables track together very closely, indicating that they are highly correlated in the model. These variables were set to their lowest category (with a mean value of 27.5) to represent the violent leader, and to their highest category (with a mean value of 72.5) to represent the peaceful leader. We then generated 1050 cases for each of these two personalities simulating the values of 25 non-personality variables included in the model. Since each case was dependent only on the original personalities we specified, but was independent of every other case, we split up the cases into 5 samples of 210 cases each. To test whether and how quickly the model converged to the original personality values, we loaded 210 cases into the model sequentially and plotted the series of personality variable values that resulted with each added case. Figure 6 and Figure 7 display these results, for the two prosocial personality variables, Affiliation Motive and Social Responsibility. In each of these figures, the original values set for the personality variables are indicated by dashed lines, with the shorter dashes indicating the peaceful personality and the longer dashes indicating the violent personality. Original - Violent Haniyeh and Hamas Case Results 80 Aff Motive Expected Value Expected Value 52 50 48 46 44 42 Feb 8 May 19 Affiliation Motive Jun 9 Jun 12 Sample 3 - Violent Sample 4 - Violent Sample 5 - Violent Original - Peaceful 60 Sample 6 - Peaceful 50 Sample 7 - Peaceful 40 Sample 8 - Peaceful Sample 9 - Peaceful 30 Violent 20 0 Past Violence Sample 2 - Violent Peaceful 70 40 Initial Sample 1 - Violent Affiliation Motive (Aff Motive) 50 Jun 24 100 150 Sample 10 - Peaceful 200 Number of Cases Social Responsibility Figure 6 Affiliation Motive values as a function of the number of cases input to the model. Figure 5. Expected value of personality variables given evidence from cases. Original - Violent Sample 1 - Violent Social Responsibility (SR) Validation of the Model 80 SR Expected Value To validate the model, we tested whether it could discriminate well between highly violent and highly peaceful personalities using only case findings that did not include information about personality. First, we set up two notional personalities: one highly violent and one highly peaceful. Next, we generated a random set of cases based on the leader personality to correspond to observable events and actions by the leader and group in question. Finally, we tested to see whether and how fast the model could recover the original personalities we specified, using only the cases. To test how reliable the model was at discriminating between personalities, we ran this validation for multiple samples of cases. In the first step, we specified values for the personality variables corresponding to a highly violent and a highly peaceful individual. Two personality variables were relevant, Social Responsibility and Affiliation Motive. Peaceful 70 Sample 2 Sample 3 Sample 4 Sample 5 - Violent Violent Violent Violent Original - Peaceful Sample 6 - Peaceful Sample 7 - Peaceful Sample 8 - Peaceful 60 50 40 Sample 9 - Peaceful Sample 10 - Peaceful 30 Violent 20 0 50 100 150 200 Number of Cases Figure 7. Social Responsibility values as a function of the number of cases input to the model. Because they are independent, the five samples do not follow exactly the same path, but all tend toward the original value of each personality variable. The convergence appears to be faster for the violent leader than 134 for the peaceful leader. Since the peaceful and violent samples diverge from 50 in opposite directions, it is clear that the model successfully discriminates. Furthermore, a two sample t-tests assuming unequal variance showed highly significant differences between the violent and peaceful leaders at the end of the simulation for both affiliation motive (t = -23.03, p < .0001) and social responsibility (t = -28.79, p < .0001). violence, restrictions on the amount of evaluation data, and the limited validation analysis. The focus of the model on group violence limits the number of personality variables that can be predicted. A more comprehensive personality prediction model would consider a much wider range of leader and group actions, categorized along several dimensions and would link to a larger group of personality variables. In fact, the primary benefit of the model comes when it incorporates many personality variables. In that case, personalities estimated by the model could be used to predict novel types of behaviors that had never been observed, but that were related to known personality variables. The results of the current research suggest that the development of a more comprehensive model might be both feasible and useful. The model validation was limited because it relied on simulated, rather than actual cases. The simulated cases are guaranteed to be independent, while the independence of actual cases must be established or assumed. Furthermore, the use of simulated cases avoids the problem of coding evidence according to the levels of the model variables. Finally, the simulated data used in the model validation assume that the model accurately reflects the relationship between the variables included in it. Since models are always imperfect representations of reality, there is a possibility that the model validation gives an overly optimistic view of the validity of the model predictions. The limitations of the current results are typical of research in an early state of development. The preliminary results are promising, but they are still preliminary. Overall, they support the belief that Bayesian networks provide a good platform for making inferences about leader personality from actions of the leader and of the group that he or she leads. Discussion and Conclusions The primary goal of the effort was to develop methods to infer leader personality from information about leader and group actions and about the situational context in which these actions occur. Central to this proof-of-concept are the goals to demonstrate the feasibility of the method and the validity of the inferences made using it. Although the results are limited by the preliminary nature of this research, we believe that they are positive regarding both feasibility and validity. Regarding feasibility, the modeling effort has overcome several obstacles in building the predictive personality model, including developing a model structure that supports proper consideration of actions, situations, and group characteristics to make inferences about leader personality. In addition, to implement the model, it was necessary to develop procedures to estimate conditional probability distributions of variables using information from a variety of sources, ranging from academic research results to expert opinion. These procedures were implemented so that analysts using the model will not need to estimate large conditional probability tables. The application of the model to the conflict between Fatah and Hamas demonstrates the feasibility of using the approach in a realistic situation. Although, it was sometimes difficult to make some of the assessments required by the model, these judgments were possible, and the results reasonably reflect expectations about the personality of the Hamas leader, Haniyeh. The results of the validation for the model show that it can recover personality information from independent cases that describe leader and group actions, group characteristics, and situational variables. Although this result has limited application to realistic situations in which the independence of cases cannot be ensured, it demonstrates that the model is sensitive to the variables that can predict leader personality. Although the model requires a relatively large number of cases to converge on the correct personality values, it can effectively distinguish extreme personalities with a much smaller number of cases. In addition, the model provides a logical way to organize the many situational, leader, and group variables that are associated with political violence. This feature of the model provides a benefit to users in addition to the accuracy of the predictions. The generally positive results should be interpreted in light of some of the limitations of the research, which might come from the exclusive focus of the model on Acknowledgments This work was supported by the Air Force Research Laboratory. The authors wish to thank Professor Fathali M. 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