Attenuation of the Köhler Effect in Racially Dissimilar Partnered Exercise Reversed Using Team Identity Strategy

The authors describe two research experiments exploring the influence of race on the Köhler motivation gain effect with exercise tasks. Experiment 1 tested whether partner racial dissimilarity affects individual performance. Experiment 2 created a team identity recategorization intervention to potentially counter the influence on performance observed in Experiment 1. White male participants were partnered with either a Black or Asian partner (Experiment 1) or with a Black partner utilizing team names and shirt colors as a team identity recategorization strategy (Experiment 2). Racially dissimilar dyads completed two sets of abdominal plank exercises with a Köhler conjunctive task paradigm (stronger partner; team performance outcome dependent upon the weaker-ability participant's performance). The results of Experiment 1 suggest attenuation of the previously successful group motivation gain effect in the racially dissimilar condition. The simple recategorization strategy utilized in Experiment 2 appeared to reverse motivation losses under conjunctive-task conditions in racially dissimilar exercise dyads.

Control of Pelvic Blood Flow Using a Novel Pneumatic Abdominal Binder

Background Obstetrical hemorrhage continues to be the leading cause of maternal death; additional means of treatment are needed to reach women who are currently not being saved. We developed the "Ball and Binder", an inexpensive and innovative pneumatic abdominal-pelvic compression device made with a cloth binder and soccer ball. Objective To measure the change in distal aortic blood flow before and after placement of the device. Method A comparative study was done on nine healthy volunteers measuring the flow in the distal aorta before and after placement of a pneumatic abdominal binder. Result Distal aortic flow decreased by over half when the device was inflated. Conclusion An inexpensive pneumatic external abdominal compression "Ball and Binder" device was able to decrease flow to the pelvis by over half. This provides an additional tool for rapid treatment of postpartum hemorrhage unresponsive to routine initial measures.

Group dynamics motivation to increase exercise intensity with a virtual partner

BACKGROUND

The effect of the Köhler group dynamics paradigm (i.e., working together with a more capable partner where one's performance is indispensable to the team outcome) has been shown to increase motivation to exercise longer at a strength task in partnered exercise video games (exergames) using a software-generated partner (SGP). However, the effect on exercise intensity with an SGP has not been investigated. The purpose of this study was to examine the motivation to maintain or increase exercise intensity among healthy, physically active middle-aged adults using an SGP in an aerobic exergame.

METHODS

Participants (n = 85, mean age = 44.9 years) exercised with an SGP in a 6-day cycle ergometer protocol, randomly assigned to either (a) no partner control, (b) superior SGP who was not a teammate, or (c) superior SGP as a teammate (team score was dependent on the inferior member). The protocol alternated between 30-min continuous and 4-min interval high-intensity session days, during which participants could change cycle power output (watts) from target intensity to alter distance and speed.

RESULTS

Mean change in watts from a targeted intensity (75% and 90% maximum heart rate) was the primary dependent variable reflecting motivational effort. Increases in performance over baseline were demonstrated without significant differences between conditions. Self-efficacy and enjoyment were significantly related to effort in the more intense interval sessions.

CONCLUSION

Under these conditions, no Köhler effect was observed. Exercise performance during the higher-intensity interval format is more closely related to enjoyment and self-efficacy beliefs compared to the continuous sessions.

Should jurors be allowed to discuss trial evidence before deliberation?: New research evidence

Traditionally, jurors are not permitted to discuss trial evidence with one another prior to jury deliberation. Allowing such discussions, at least in civil trials, is a jury innovation that has become increasingly popular. Prior field research has generally supported the assumption that this innovation is benign and, in particular, introduces no systematic bias in jury verdicts. These issues are examined again here within an experimental jury simulation study. The opportunity for predeliberation juror discussion (PJD) between the plaintiff and defense cases-in-chief was manipulated. The results revealed that PJD biased jury verdicts. The nature of this bias was not, as commonly suspected, a commitment to evidence heard prior to PJD, but rather a greater weight placed on evidence heard following the PJD. One good explanation of this bias was that jurors acted as if evidence heard prior to PJD had "already been covered" during the PJD, and so primary attention was given to post-PJD evidence in jury deliberations. Little evidence was found to corroborate several other purported benefits or drawbacks of PJD. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Intergroup Competition in Exergames: Further Tests of the Köhler Effect

OBJECTIVE

We examined how competing with a software-generated partner (SGP) against another human/virtual partner team, in an exercise video game (exergame), affects individual motivation as measured by effort.

MATERIALS AND METHODS

Participants (n = 90; 49 female; Mage = 19.93 ± 1.48) were randomly assigned to one of three conditions: individual control (IC); conjunctive partner, no competition (PNC); or conjunctive partner, with competition (PWC). Participants performed the first series of exercises alone. After resting, those in the partnered conditions performed the remaining trials with a same-sex SGP. Those in the PWC condition were told that they and their virtual partner would be competing against another human-virtual partner team.

RESULTS

A significant motivation gain was observed in both partnered conditions compared to control (P < 0.001), but the partnered groups did not differ significantly. However, participants in the PWC condition enjoyed the task significantly (P < 0.05) more than those in the PNC and IC conditions and the PWC participants identified more with the SGP as a teammate than the PNC participants.

CONCLUSIONS

Altogether, intergroup competition with an SGP may be an enjoyable way to enhance motivation and performance while exercising.

Introductory Dialogue and the Köhler Effect in Software-Generated Workout Partners

OBJECTIVES

This study explored the Köhler motivation gain effect utilizing adults and software-generated partners (SGPs) during an abdominal exercise regimen and compared the type of participant-SGP introductory dialogue as a moderator. The Köhler effect applies interdependent team dynamics in which group performance is dependent upon the weaker member. The third objective was to examine if this motivation paradigm would result in adverse consequences to secondary variables: exertion, enjoyment, and self-efficacy beliefs.

DESIGN

Adults (M_age = 38.8 +/- 7.7) were randomly assigned to 1 of 3 conditions: Interactive Partner SGP (IP), Linear Dialogue Partner SGP (LDP), or individual control (IC), to complete a series of abdominal exercises. The experiment used a 3 (condition) x 2 (gender) ANCOVA design, with a baseline block of exercises as a covariate.

METHOD

Participants completed abdominal exercises individually and, after a rest, repeated the same exercises with either an SGP programmed to be moderately stronger or individually (IC). Prior to the second exercise block, IP participants interacted with the SGP using a dialog tree optional-response format. The LDP participant introduction was a linear, scripted exchange of basic information.

RESULTS

The LDP and IP conditions persisted significantly longer than IC, generating moderate effect sizes (d = .62; d = .76). The mean difference between partnered conditions was not significant.

CONCLUSIONS

The Köhler motivation exercise paradigm resulted in a considerable increase in persistence (M_adj = 28.9, SE = 10.6) in the first study to use middle-aged adults with superior SGPs. Differences between introductory dialogue methods were not significant.

The most neglected moderator in group research

This paper argues that the group’s task is the most neglected moderator in group research. After offering a broad conception of group task, I draw on various sources to illustrate the powerful moderating role of group task and the field’s broad neglect of this moderation. I conclude with some suggestions for how we might better acknowledge and address the importance of group task for group behavior.

Sleep Deprivation Impairs and Caffeine Enhances My Performance, but Not Always Our Performance

What effects do factors that impair or enhance performance in individuals have when these individuals act in groups? We provide a framework, called the GIE ("Effects of Grouping on Impairments and Enhancements") framework, for investigating this question. As prominent examples for individual-level impairments and enhancements, we discuss sleep deprivation and caffeine. Based on previous research, we derive hypotheses on how they influence performance in groups, specifically process gains and losses in motivation, individual capability, and coordination. We conclude that the effect an impairment or enhancement has on individual-level performance is not necessarily mirrored in group performance: grouping can help or hurt. We provide recommendations on how to estimate empirically the effects individual-level performance impairments and enhancements have in groups. By comparing sleep deprivation to stress and caffeine to pharmacological cognitive enhancement, we illustrate that we cannot readily generalize from group results on one impairment or enhancement to another, even if they have similar effects on individual-level performance.

HARKing: Hypothesizing After the Results are Known

This article considers a practice in scientific communication termed HARKing (Hypothesizing After the Results are Known). HARKing is defined as presenting a post hoc hypothesis (i.e., one based on or informed by one's results) in one's research report as if it were, in fact, an a priori hypotheses. Several forms of HARKing are identified and survey data are presented that suggests that at least some forms of HARKing are widely practiced and widely seen as inappropriate. I identify several reasons why scientists might HARK. Then I discuss several reasons why scientists ought not to HARK. It is conceded that the question of whether HARKing's costs exceed its benefits is a complex one that ought to be addressed through research, open discussion, and debate. To help stimulate such discussion (and for those such as myself who suspect that HARKing's costs do exceed its benefits), I conclude the article with some suggestions for deterring HARKing.

Simulated Partners and Collaborative Exercise (SPACE) to boost motivation for astronauts: study protocol

Background

Astronauts may have difficulty adhering to exercise regimens at vigorous intensity levels during long space missions. Vigorous exercise is important for aerobic and musculoskeletal health during space missions and afterwards. A key impediment to maintaining vigorous exercise is motivation. Finding ways to motivate astronauts to exercise at levels necessary to mitigate reductions in musculoskeletal health and aerobic capacity have not been explored. The focus of Simulated Partners and Collaborative Exercise (SPACE) is to use recently documented motivation gains in task groups to heighten the exercise experience for participants, similar in age and fitness to astronauts, for vigorous exercise over a 6-month exercise regimen. A secondary focus is to determine the most effective features in simulated exercise partners for enhancing enjoyment, self-efficacy, and social connectedness. The aims of the project are to (1) Create software-generated (SG) exercise partners and interface software with a cycle ergometer; (2) Pilot test design features of SG partners within a video exercise game (exergame), and (3) Test whether exercising with an SG partner over 24-week time period, compared to exercising alone, leads to greater work effort, aerobic capacity, muscle strength, exercise adherence, and enhanced psychological parameters.

Methods/Design

This study was approved by the Institutional Review Board (IRB). Chronic exercisers, between the ages 30 and 62, were asked to exercise on a cycle ergometer 6 days per week for 24 weeks using a routine consisting of alternating between moderate-intensity continuous and high-intensity interval sessions. Participants were assigned to one of three conditions: no partner (control), always faster SG partner, or SG partner who was not always faster. Participants were told they could vary cycle ergometer output to increase or decrease intensity during the sessions. Mean change in cycle ergometer power (watts) from the initial continuous and 4 min. interval sessions was the primary dependent variable reflecting work effort. Measures of physiological, strength, and psychological parameters were also taken.

Discussion

This paper describes the rationale, development, and methods of the SPACE exergame. We believe this will be a viable intervention that can be disseminated for astronaut use and adapted for use by other populations.

Enhancing Aerobic Exercise with a Novel Virtual Exercise Buddy Based on the Köhler Effect

OBJECTIVE

Research on active videogames (AVGs) has demonstrated the motivation-boosting power of the Köhler effect (a motivating force for "weak links" in groups based on group principles of upward social comparison and indispensability) with software-generated partners (SGPs), but the effect has yet to be examined over time. We tested the viability of the Köhler effect in an AVG with an SGP over 12 exercise sessions using a cycle ergometer and whether a fatiguing partner (FP) could further boost the effect.

MATERIALS AND METHODS

A repeated-measures design was used to assess mean changes in exercise persistence over time. Participants were randomly assigned to one of three game conditions: AVG alone (individual-control [IC]), AVG with a consistently superior partner (CSP), or AVG with a superior partner who showed signs of fatigue (FP). Assessments were conducted on 82 participants (42 college students and 40 adults from the community) in a laboratory over 12 experimental sessions. The main outcome measure was exercise persistence (minutes of gameplay cycling at 75% HRmax).

RESULTS

Data yielded significant improvements in exercise duration for men in the FP condition when compared with men in the IC condition (Mdiff = 12:32 minutes, SEdiff = 4:54). Women showed no change in exercise persistence over time and no condition differences.

CONCLUSION

Exercising in an AVG with a superior SGP, who shows signs of fatigue over time, improved exercise persistence for men but not for women under present experimental conditions.

On the Virtues of Assuming Minimal Differences in Information Processing in Individuals and Groups

The metaphor of groups as information processors has been gaining in popularity. If this metaphor’s utility is to be fully exploited, it is first necessary to distinguish - conceptually, theoretically, and empirically - when and how information processing in groups is any different from information processing in individuals. In this paper, several varieties or levels of group information processing are first conceptually distinguished. It is argued that differences between individual and group information processing which are manifest in differences between individual and group output are of greatest interest. However, it is further argued that such individual-group differences in output are not unfailing indicators of such interesting differences in processing. Two empirical illustrations are provided. It is further argued that (a) predictive models assuming little or no individual-group difference in information processing are particularly useful for detecting genuine instances of distinctive group information processing, and (b) that social combination models (such as Davis’ social decision scheme model, 1973) provide one particularly useful class of such models.

Identifiability, Performance Feedback and the Köhler Effect

Research, starting with Köhler (1926), has demonstrated a type of group motivation gain, wherein the less capable member of a dyad working conjunctively at a persistence task works harder than comparable individuals. To explore possible boundary conditions of this effect, the current experiment systematically varied the amount and timing of performance feedback group members received. Results showed: (a) continuous feedback of both members’ performance was not necessary for producing the effect; (b) the effect was attenuated, but not eliminated by delaying and restricting feedback, such that group members only learned which of them was the less capable worker (but not how long s/he persisted) sometime after the task trial was completed; and (c) the motivation gain was eliminated in the absence of any performance feedback (i.e. when neither worker could tell who quit first nor how long either had persisted). Some implications of these results for currently viable explanations of the Köhler effect are discussed. It is concluded that the effect is likely to result from several distinct processes.

Social Compensation: Fact or Social-Comparison Artifact?

The use of coactors as non-group controls in prior social compensation research has left open the possibility that the effect might artifactually have resulted from a confound between work condition (Coaction vs. Collective) and the opportunity to make performance comparisons. A direct empirical test of this alternative, artifactual explanation is reported. Its results contradict that explanation and suggest that the use of coactors as controls has, if anything, resulted in an underestimation of the magnitude of the social compensation effect. It is argued that multiple alternative non-group performance baselines can be informative for analyzing group motivation effects.

Having to Take a Stand: The Interactive Effects of Task Framing and Source Status on Attitudes

Some research has found that a minority message source is less persuasive than a majority source on personally relevant issues. In that research, participants were forewarned that they would have to report their attitudinal reactions. We hypothesized that if recipients were given an opinion-irrelevant (recall) task instead, source status would not affect attitudes. Participants were asked to read a strong, outcome-relevant, counterattitudinal persuasive essay presented by a minority or majority source under opinion or recall task directions. The minority was less persuasive than the majority in the opinion task condition, and this effect was mediated by source evaluation and favorable cognitive elaboration. No source status effects emerged in the recall task condition.

Jury Verdicts

This study examined the following question: How well will a predictor of an individual juror's decision preference predict the verdict of the jury to which that individual belongs? A simulation study or "thought experiment " was performed. Using basic probability theory and the social decision scheme model of the jury decision-making process, it was possible to determine how strongly a juror characteristic would be related to his or her jury's verdict from a knowledge of how strongly that characteristic was related to his or her own personal verdict preference. For 12-person juries, the predictor accounted for less than 5% as much variance in juries' behavior as it did in jurors' behavior, regardless of the overall rate of conviction for jurors or the strength with which individual decisions were predicted. Although decreasing the jury size tended to increase this percentage, it remained quite small, even for dyads. Quite similar results were found when alternative decision schemes were employed. It was also shown that when the members of the jury are uniformly high or low on some characteristic, the predictor variable is generally related to group verdicts more strongly than it is to individual verdicts.

That Still, Small Voice: Commitment to Cooperate as an Internalized Versus a Social Norm

Recent research suggests that group discussion of a social dilemma may increase cooperative behavior because group members honor the commitments they make during the group discussion. This article asks whether people honor such commitments because of the social consequences of violating them or because of the internal personal consequences of doing so. Experiment 1 replicated and extended previous research showing that the anonymity of one's cooperative/noncooperative choice does not moderate the effect of group discussion. Experiment 2 examined the possibility that commitments to cooperate were kept due to mindless adherence to a prior decision, rather than to an internalized norm. Contrary to the former possibility, enhancing mindfulness did not moderate the effect of group discussion. The scope and implications of personal norms of commitment are discussed.

Ringelmann Revisited

Recent work suggests that group members' motivation for certain types of tasks declines as group size increases. Two experiments examined alternative explanations for this effect. The results of the first study disconfirmed the "me first" explanation, which holds that the effect occurs only when an individual performs in several different size groups. The second experiment supported the "hide-in—the crowd"explanation, which holds that member anonymity increases with group size for the tasks which have yielded the effect.

Stereotypes and Nonstereotypic Judgments

The effects of a target individual's gender role attitudes on nonstereotypic judgments were examined in this research. Male and female subjects judged the likability, adjustment, and occupational potential of targets who were either traditional or nontraditional in their attitudes toward women. The results indicated that whereas female subjects consistently evaluated nontraditional targets more favorably than traditional targets, the ratings of male subjects depended on the target's gender and the evaluation dimension in question. Implications of the readiness with which stereotypic information implicated other evaluative schema are discussed.

Beautiful and Blameless: Effects of Victim Attractiveness and Responsibility on Mock Jurors' Verdicts

The physical attractiveness of the victim of a crime and the victim's precautiousness were varied in a factorial design. The primary finding was an interaction effect on mock jurors' personal verdicts; the defendant was most likely to be convicted when the victim was both beautiful and blameless.

Role Schemata and Member Motivation in Task Groups

It was conjectured that occupying the minimal leader role (i.e., having the title of group leader without having any of the attendant legitimacy, power, authority, or formal responsibility) might trigger a leader role schema that prescribes greater responsibility for group performance. In an experimental study, the effects of occupying such a minimal leader role and its complementary, minimal nonleader role on three distinct group motivation losses were explored. Occupying the minimal leader role did not, as conjectured, attenuate these motivation losses. However occupying the minimal nonleader role did affect task motivation. The clearest such effect was an accentuation of the typical social loafing effect by subjects when someone else in the group had been selected as a group leader

Cyber Buddy Is Better than No Buddy: A Test of the Köhler Motivation Effect in Exergames

OBJECTIVE

Although exergames are popular, few people take advantage of the potential of group dynamics to motivate play (and achieve associated health benefits). One motivation gain phenomenon has shown promise for motivating greater effort in partnered exergames: The Köhler effect (working at a task with a more capable partner where one's performance is indispensable to the group). This article examines whether a Köhler effect can be demonstrated in an exergame by exercising with a moderately superior humanoid, software-generated partner.

MATERIALS AND METHODS

Male and female (n=120; mean age, 19.41 years) college students completed a series of plank exercises using "CyBuddy Exercise," a program developed specifically for this study. In a lab in an academic building, participants completed the exercises individually and, after a rest, were randomly assigned to complete the same exercises again, but with a "live" human partner (HP) presented virtually, a nearly-human-like, humanoid partner (NHP), a hardly human-like, software-generated partner (HHP), or a no-partner control condition (IC), with equal numbers in each group (i.e., n=30). Exercise persistence, perceived exertion, self-efficacy beliefs, enjoyment, and intentions to exercise were recorded and analyzed.

RESULTS

A 4×2 analysis of variance on the (Block 2 - Block 1) difference scores showed that a significant Köhler motivation gain was observed in all partner conditions (compared with IC), but persistence was significantly greater with HPs than with either NHP or HHP humanoid partners (P<0.05). By the conclusion of the study, there were no significant differences among the partnered conditions in perceived exertion, self-efficacy, enjoyment, or future intentions to exercise.

CONCLUSIONS

These results suggest that a software-generated partner can elicit the Kőhler motivation gain in exergames, but not as strongly as a partner who is thought to be human.

Silence is golden: effect of encouragement in motivating the weak link in an online exercise video game

Background

Despite the physical and mental health benefits, few adults meet US Department of Health and Human Services physical activity guidelines for exercise frequency, intensity, and duration. One strategy that may increase physical activity duration is exercising with an Internet partner (ie, someone who is virtually present, as in video chat). Internet partners help people overcome many barriers associated with face-to-face exercise groups (eg, time, coordinating schedules, social physique anxiety). Past research examining individual performance in groups suggests that an increase in effort occurs when performing a task conjunctively, ie, when a participant is (1) less capable than fellow group members, and (2) participants efforts are particularly indispensable for group success (ie, where the group’s potential productivity is equal to the productivity of its least capable member). This boost in effort is more commonly known as the Köhler effect, named after the German psychologist who first observed the effect. While encouragement between group members is common practice in face-to-face group exercise, the effect of encouragement between partners exercising conjunctively across the Internet is unknown.

Objective

To examine the impact of exercising alone, compared to exercising conjunctively with an Internet partner, both with and without encouragement, on exercise persistence (primary outcomes) and secondary psychosocial outcomes (self-efficacy, enjoyment, exercise intention).

Methods

Participants were recruited online and face-to-face from the campus of Michigan State University. With the assistance of the experimenter, participants (n=115) played an exercise video game in a laboratory, performing a series of five abdominal plank exercises where they were asked to hold the plank for as long as possible (Time 1). They were then randomized to a condition (Individual, Partner-without-encouragement, or Partner-with-encouragement), where they performed the exercises again (Time 2). The impact of condition on the primary outcome measures and secondary outcome measures were evaluated using a 2 (Gender) x 3 (Condition) ANOVA on change scores (Time 2-Time 1).

Results

Those who exercised in online teams (n=80) exercised significantly longer (time=78.8s, P<.001) than those who worked individually (n=35). However, exercise duration was shorter when one’s more capable partner gave verbal encouragement (n=55) than when s/he did not (n=25) (a mean difference of 31.14s). These increases in effort were not accompanied by altered task self-efficacy, enjoyment of the task, or intention to exercise in the future.

Conclusions

Exercising conjunctively with an Internet partner can boost one’s duration of exercise. However, encouragement from the stronger to the weaker member can mitigate these gains, especially if one perceives such comments being directed at someone other than themselves. To boost exercise duration, Internet-based physical activity interventions involving group interaction should make relative abilities of participants known and communication clear.

Scientific inquiry on how groups decide: The Davisonian approach

This special issue of GPIR is a tribute to the many contributions to the scientific study of group processes made by James H. Davis, who died on November 16, 2010. In this brief introductory piece, we will provide a bit of background on Jim’s life and work, describe his characteristic method of inquiry, which we might term the Davisonian approach, and preview the papers in this issue, each of which illustrate aspects of that Davisonian approach and make an original contribution to our understanding of group behavior.

Is the leniency asymmetry really dead? Misinterpreting asymmetry effects in criminal jury deliberation

Early jury simulation research, reviewed and meta-anyalysed by MacCoun and Kerr (1988), suggested a leniency asymmetry in criminal jury deliberations such that a given faction favoring acquittal will tend to have a greater chance of prevailing than would an equivalent sized faction favoring conviction. More recently, a handful of field studies of actual juries have reported either no such leniency asymmetry or one in the opposite direction (a severity asymmetry). A potential bias in the coding of these field studies’ data is identified, one that would tend to underestimate any leniency asymmetry. The data from three field studies are re-analyzed after correcting this purported coding bias. The results of these re-analyses show a leniency asymmetry effect, although one that is less pronounced than observed in mock jury studies. It is argued that this difference in degree (not existence) of leniency asymmetry can plausibly be attributed to greater imbalance in evidence strength in the typical actual trial relative to the typical stimulus case in simulation experiments. It is also noted that failure to observe such a leniency asymmetry effect in actual juries would raise important questions about their adherence to the reasonable doubt standard of proof.

To pay or not to pay? Do extrinsic incentives alter the Köhler group motivation gain?

The Köhler effect is an increase in task motivation that occurs in performance groups when one is (a) less capable than one’s fellow group members, and (b) one’s efforts are particularly indispensible for group success. Recently, it has been shown that the Köhler effect can dramatically increase one’s motivation to exercise. The present study examines the potential moderating effect of the provision of extrinsic incentives on such Köhler motivation gains. When participants were offered such an extrinsic incentive for persisting at an exercise task, a robust Köhler effect was observed—participants who thought they were the less capable member of a dyad working at a conjunctive-group exercise task persisted 26% longer than comparable individual exercisers. But an even stronger effect (a 43% improvement) was observed when no such incentive was on offer. Possible explanations and boundary conditions for this moderating effect are discussed.

Buddy up: the Köhler effect applied to health games

The present investigation examined the Köhler motivation gain effect in a health game using an absent partner, presented virtually. The Köhler effect occurs when an inferior team member performs a difficult task better in a team or coaction situation than one would expect from knowledge of his or her individual performance. The effect has been strongest in conjunctive task conditions in which the group's potential productivity is equal to the productivity of its least capable member. Participants were randomly assigned to one of four conditions (individual control, coaction, additive, and conjunctive) in a 4 (conditions) • 2 (gender) factorial design and performed a series of isometric plank exercises within an exercise game. They performed the first series of five exercises alone holding each position for as long as they could, and, after a rest period, those in the partner conditions were told they would do remaining trials with a same-sex virtual partner whom they could observe during their performance. The partner's performance was manipulated to be always superior to the participant's. Results showed that task persistence was significantly greater in all experimental conditions than in the individual control condition. The conjunctive condition was no more motivating than either the additive or coactive conditions. Results suggest that working out with virtually present, superior partners can improve persistence motivation on exercise game tasks.

Fertility and Intergroup Bias in Racial and Minimal-Group Contexts

Recent research has shown that White women’s bias against Black men increases with elevated fertility across the menstrual cycle. We demonstrate that the association between fertility and intergroup bias is not limited to groups defined by race, but extends to group categories that are minimally defined, and may depend on the extent to which women associate out-group men with physical formidability. In Study 1, Black and White women with strong associations between the racial out-group and physical formidability displayed greater bias against out-group men as conception risk increased. Study 2 replicated these results in a minimal-group paradigm. These findings are consistent with the notion that women may be endowed with a psychological system that generates intergroup bias via mechanisms that rely on categorization heuristics and perceptions of the physical formidability of out-group men, particularly when the costs of sexual coercion are high.

Evaluation Concerns and the Köhler Effect

This study examined whether increasing evaluation concerns would increase the magnitude of the Köhler effect (i.e., one type of motivation gain that has been documented to occur in small groups). Evaluation concerns were manipulated by having participants work in the physical presence or virtual presence of their coworker. As anticipated, motivation gains were significantly greater for participants who worked in the physical presence of their coworker. These results suggest that evaluation concerns can potentially increase the magnitude of the Köhler effect. Furthermore, the findings have implications for practitioners and researchers interested in the differential impact that face-to-face and virtual mediums have on motivation in groups or teams.

Group-to-Individual Problem-Solving Transfer

Many scientific, educational, business, military, and political groups assume that people who solve problems in groups and teams will solve subsequent problems better as individuals than people without previous group problem-solving experience. In order to assess such group-to-individual transfer, sets of three people solved four letters-to-numbers decoding problems as groups (G) or individuals (I) in five conditions: GGGG, GGGI, GGII, GIII, or IIII. Results supported four hypotheses: (a) groups performed better than individuals, (b) positive group-to-individual transfer occurred, (c) one group experience was sufficient for transfer, (d) transfer was at the level of group performance (complete) on problems 2 and 3 but incomplete on problem 4, due to exceptional performance in the GGGG condition.

Psychological mechanisms underlying the Köhler motivation gain

Sometimes group work conditions lead to motivation gains rather than to social loafing. Two theoretical explanations for the Köhler motivation gain effect are identified, one stressing social comparison and a second stressing the indispensability of one's effort to the group. The results of three new experiments are reported. Experiment 1 suggested that both explanations are valid and contribute to the Köhler effect. Prior studies suggested that there might be gender differences in the relative importance of these two explanatory processes. Experiment 2 confirmed this suggestion. In Experiment 3, the gender difference was eliminated by priming women with a goal (viz., competition) presumed to be chronically more important to men. It is argued that the relative importance of these two motivational processes will depend on the immediate and chronic importance attached to more personal (viz., to achieve a favorable social comparison) versus collective (viz., to contribute to one's group) goals.

Chaos in the courtroom reconsidered: emotional bias and juror nullification

A widespread presumption in the law is that giving jurors nullification instructions would result in "chaos"-jurors guided not by law but by their emotions and personal biases. We propose a model of juror nullification that posits an interaction between the nature of the trial (viz. whether the fairness of the law is at issue), nullification instructions, and emotional biases on juror decision-making. Mock jurors considered a trial online which varied the presence a nullification instructions, whether the trial raised issues of the law's fairness (murder for profit vs. euthanasia), and emotionally biasing information (that affected jurors' liking for the victim). Only when jurors were in receipt of nullification instructions in a nullification-relevant trial were they sensitive to emotionally biasing information. Emotional biases did not affect evidence processing but did affect emotional reactions and verdicts, providing the strongest support to date for the chaos theory.