Associations between Symptom Validity Test failure and scores on the MMPI-2-RF validity and substantive scales

This study examined the association between Symptom Validity Test (SVT) failure and the Minnesota Multiphasic Personality Inventory-2 Restructured Form (MMPI-2-RF; Ben-Porath & Tellegen, 2008), in the Forensic Disability Claimant samples described in the MMPI-2-RF Technical Manual (Tellegen & Ben-Porath, 2008 a, 2008b). SVTs used included the Word Memory Test (Green, 2003), the Computerized Assessment of Response Bias (Allen, Conder, Green, & Cox, 1997), the Medical Symptom Validity Test (Green, 2004), and the Test of Memory Malingering (Tombaugh, 1996). SVT failure was associated with significant elevations throughout the MMPI-2-RF overreporting validity scales and substantive scales. Pairwise contrasts between groups failing 0 and 3 SVTs revealed predominantly large effect sizes for the overreporting validity scales (d = 0.78-1.11), and many of the substantive scales, including the Cognitive Complaints (COG) scale. Results of this study demonstrate an association between SVT performance and elevated scores on the MMPI-2-RF. These results suggest that exaggeration of cognitive symptoms as demonstrated by SVT failure is also associated with overreported emotional, somatic, and neurocognitive complaints on the MMPI-2-RF.     

The MMPI-2 computerized adaptive version (MMPI-2-CA) in a Veterans Administration medical outpatient facility

The ability to screen quickly and thoroughly for psychological difficulties in existing and returning combat veterans who are seeking treatment for physical ailments would be of significant benefit. In the current study, item and time savings, as well as extratest correlations, associated with an audio-augmented version of the computerized adaptive Minnesota Multiphasic Personality Inventory-2 (MMPI-2-CA) are examined in a group of 273 male veterans, ages 26-87 years. Results indicated an average item savings of approximately 103 items (18.6%), with a corresponding time savings of approximately 12 min (24.3%), for the MMPI-2-CA compared with conventional computerized administration of the test, as well as comparability in terms of test-retest coefficients and correlations with external measures. Future directions of adaptive personality testing are discussed.     

Embedding social dilemmas in intergroup competition reduces free-riding

We study a class of multi-level collective actions, in which each individual is simultaneously engaged in an intragroup conflict and intergroup competition. The intragroup conflict is modeled as an n-person Prisoner’s Dilemma game, in which the dominant strategy is to contribute nothing. The intergroup competition is for an exogenous and commonly known prize shared by members of the winning group. We focus on the effects on the level of contribution of the two most common sharing rules for dividing the prize, equal and proportional. Our results show that (1) embedding the intragroup conflict in intergroup competition markedly reduces free riding; (2) the proportional profit sharing rule significantly outperforms the egalitarian rule, and the difference between the two increases with experience; (3) under egalitarian but not under proportional sharing, there is over-contribution compared to theoretical predictions, and (4) a simple reinforcement-based learning model accounts for the aggregate results of all five experimental conditions.     

Intergroup competition for the provision of step-level public goods: Effects of preplay communication

Thirty-two groups of three subjects each participated once in an intergroup public goods game (IPG) in which two groups compete for the provision of step-level public goods. Half of the groups were allowed to discuss the conflict before their members decided privately and anonymously whether to contribute their endowments to their group benefit, and half were not given this opportunity. The results show that preplay group discussion enhances the percentage of contributors and changes the players' estimates about the decisions of the other players. The theoretical implications of the results are examined within the framework of a new model which relates the individual decision to contribute or not to the reward structure, altruism, and the individual's belief structure.     

Quota vs positional power in four-person apex games

In coalition formation experiments, which coalitions will form and how players in coalitions will allocate their jointly gained rewards are typically predicted as a function of the players' relative power. In this paper, we isolated two logically independent sources of a player's power: the player's contribution to the rewards obtainable by coalitions of which he may be a member (“quota power”), and the number of distinct coalitions which a player may join (“positional power”). The separation of the two types of power is clearly shown in apex games, where a single player (Apex) attempts to lure any of the other players (Base) from the coalition of all Bases. A series of four-person computer-controlled apex and nonapex characteristic function games, varying with respect to the relationship of quota power to positional power, were played by 15 quartets of male players. Quota power was strongly manifested in all outcome measures, while positional power appeared only as a bias toward equal allocations of reward when coalitions among players of equal positional power formed. Neither of two social psychological theories that are applicable, pivotal power and weighted probability theory, predicted coalition frequencies. In a test of five solution concepts, the competitive bargaining set predicted payoff allocations better than either of the two aforementioned theories, the kernel, or an equal-split model.     

Subjective randomization in one-and two-person games

Following the study by Rapoport and Budescu (1992), two experiments are reported whose main purpose is to compare the generation of random sequences in one- and two-person games. The first experiment addresses the generation of trinary series in two-person zerosum games with asymmetric players. The second examines the generation of binary series using a between-subjects design, and compares the cognitive processes operating in one- and two-person games. Although both types of games result in similar deviations from randomness, they seem to induce qualitatively different cognitive processes.