The Power of a “Maverick” in Collaborative Problem Solving: An Experimental Investigation of Individual Perspective‐Taking Within a Group

Integrating different perspectives is a sophisticated strategy for developing constructive interactions in collaborative problem solving. However, cognitive aspects such as individuals’ knowledge and bias often obscure group consensus and produce conflict. This study investigated collaborative problem solving, focusing on a group member interacting with another member having a different perspective (a “maverick”). It was predicted that mavericks might mitigate disadvantages and facilitate perspective taking during problem solving. Thus, 344 university students participated in two laboratory‐based experiments by engaging in a simple rule‐discovery task that raised conflicts among perspectives. They interacted with virtual partners whose conversations were controlled by multiple conversational agents. Results show that when participants interacted with a maverick during the task, they were able to take others’ perspectives and integrate different perspectives to solve the problem. Moreover, when participants interacted in groups with a positive mood, groups with a maverick outperformed groups having several perspectives.     

NMDA signaling in CA1 mediates selectively the spatial component of episodic memory

Recent studies focusing on the memory for temporal order have reported that CA1 plays a critical role in the memory for the sequences of events, in addition to its well-described role in spatial navigation. In contrast, CA3 was found to principally contribute to the memory for the association of items with spatial or contextual information in tasks focusing on spatial memory. Other studies have shown that NMDA signaling in the hippocampus is critical to memory performance in studies that have investigated spatial and temporal order memory independently. However, the role of NMDA signaling separately in CA1 and CA3 in memory that combines both spatial and temporal processing demands (episodic memory) has not been examined. Here we investigated the effect of the deletion of the NR1 subunit of the NMDA receptor in CA1 or CA3 on the spatial and the temporal aspects of episodic memory, using a behavioral task that allows for these two aspects of memory to be evaluated distinctly within the same task. Under these conditions, NMDA signaling in CA1 specifically contributes to the spatial aspect of memory function and is not required to support the memory for temporal order of events.     

A Class of Population Covariance Matrices in the Bootstrap Approach to Covariance Structure Analysis

Model evaluation in covariance structure analysis is critical before the results can be trusted. Due to finite sample sizes and unknown distributions of real data, existing conclusions regarding a particular statistic may not be applicable in practice. The bootstrap procedure automatically takes care of the unknown distribution and, for a given sample size, also provides more accurate results than those based on standard asymptotics. But the procedure needs a matrix to play the role of the population covariance matrix. The closer the matrix is to the true population covariance matrix, the more valid the bootstrap inference is. The current paper proposes a class of covariance matrices by combining theory and data. Thus, a proper matrix from this class is closer to the true population covariance matrix than those constructed by any existing methods. Each of the covariance matrices is easy to generate and also satisfies several desired properties. An example with nine cognitive variables and a confirmatory factor model illustrates the details for creating population covariance matrices with different misspecifications. When evaluating the substantive model, bootstrap or simulation procedures based on these matrices will lead to more accurate conclusion than that based on artificial covariance matrices.     

A cluster analysis of text message users based on their demand for text messaging: A behavioral economic approach

The goal of this study was to determine whether cluster analysis could be used to identify distinct subgroups of text message users based on behavioral economic indices of demand for text messaging. Cluster analysis is an analytic technique that attempts to categorize cases based on similarities across selected variables. Participants completed a questionnaire about mobile phone usage and a hypothetical texting demand task in which they indicated their likelihood of paying an extra charge to continue to send text messages. A hierarchical cluster analysis was conducted on behavioral economic indices, such as demand intensity, demand elasticity, breakpoint, and the maximum expenditure. With the cluster analysis, we identified 3 subgroups of text message users. The groups were characterized by (a) high intensity and low elasticity, (b) high intensity and medium elasticity, and (c) low intensity and high elasticity. In a demonstration of convergent validity, there were statistically significant and conceptually meaningful differences across the subgroups in various measures of mobile phone use and text messaging. Cluster analysis is a useful tool for identifying and profiling distinct, practically meaningful groups based on behavioral indices and could provide a framework for targeting interventions more efficiently.     

Temporal modulations of agonist and antagonist muscle activities accompanying improved performance of ballistic movements

Although many studies have examined performance improvements of ballistic movement through practice, it is still unclear how performance advances while maintaining maximum velocity, and how the accompanying triphasic electromyographic (EMG) activity is modified. The present study focused on the changes in triphasic EMG activity, i.e., the first agonist burst (AG1), the second agonist burst (AG2), and the antagonist burst (ANT), that accompanied decreases in movement time and error. Twelve healthy volunteers performed 100 ballistic wrist flexion movements in ten 10-trial sessions under the instruction to "maintain maximum velocity throughout the experiment and to stop the limb at the target as fast and accurately as possible". Kinematic parameters (position and velocity) and triphasic EMG activities from the agonist (flexor carpi radialis) and antagonist (extensor carpi radialis) muscles were recorded. Comparison of the results obtained from the first and the last 10 trials, revealed that movement time, movement error, and variability of amplitudes reduced with practice, and that maximum velocity and time to maximum velocity remained constant. EMG activities showed that AG1 and AG2 durations were reduced, whereas ANT duration did not change. Additionally, ANT and AG2 latencies were reduced. Integrated EMG of AG1 was significantly reduced as well. Analysis of the alpha angle (an index of the rate of recruitment of the motoneurons) showed that there was no change in either AG1 or AG2. Correlation analysis of alpha angles between these two bursts further revealed that the close relationship of AG1 and AG2 was kept constant through practice. These findings led to the conclusion that performance improvement in ballistic movement is mainly due to the temporal modulations of agonist and antagonist muscle activities when maximum velocity is kept constant. Presumably, a specific strategy is consistently applied during practice.     

Where Grammar and Interaction Meet: A Study of Co-Participant Completion in Japanese Conversation

This article examines the practice of "co-participant completion" in Japanese conversation, and explores what kinds of resources are mobilized to provide the opportunity to complete another participant's utterance-in-progress. It suggests the following observations as potential characteristics of Japanese co-participant completion: (i) Syntactically-defined two-part formats (e.g. [If X] + [then Y]) may not play as prominent a role as in English; (ii) The majority of cases of co-participant completion take the form of 'terminal item completion;' (iii) Locally emergent structures like 'contrast' and 'list' as well as 'unprojected' features of turn construction often play an important role in enhancing the opportunity for completing another participant's utterance-in-progress. The article then discusses the implications of these findings for the investigation of the mutual bearing of grammar and social interaction. In particular, the discussion focuses on what we can learn from the practice of co-participant completion about how projection of turn-shapes is accomplished in Japanese conversation.     

On muthén’s maximum likelihood for two-level covariance structure models

Data in social and behavioral sciences are often hierarchically organized. Special statistical procedures that take into account the dependence of such observations have been developed. Among procedures for 2-level covariance structure analysis, Muthén’s maximum likelihood (MUML) has the advantage of easier computation and faster convergence. When data are balanced, MUML is equivalent to the maximum likelihood procedure. Simulation results in the literature endorse the MUML procedure also for unbalanced data. This paper studies the analytical properties of the MUML procedure in general. The results indicate that the MUML procedure leads to correct model inference asymptotically when level-2 sample size goes to infinity and the coefficient of variation of the level-1 sample sizes goes to zero. The study clearly identifies the impact of level-1 and level-2 sample sizes on the standard errors and test statistic of the MUML procedure. Analytical results explain previous simulation results and will guide the design or data collection for the future applications of MUML.This research was supported by NSF Grant DMS04-37167.We thank Dr.Bengt Muthén for providing key references. We are also grateful to three expert reviewers for their constructive comments that have led the paper to an improvement over the previous version.This revised article was published online in August 2005 with the PDF paginated correctly.     

A TEST OF McCLELLAND'S THEORY OF ACHIEVEMENT MOTIVATION IN BRITAIN,JAPAN, IRELAND AND ISRAEL

Les auteurs tirent deux hypothèses de la théorie de McClelland, selon laquelle les taux rapides de développement économique sont sous-tendus par un fort besoin de réussite. La première hypothèse pose que les étudiants des pays à forte croissance économique manifesteront une préférence pour les affaires, et la seconde qu'ils se sentiront plus concernés par la réussite professionnelle. Les recherches ont lieu au Japon et en Israel, pays à forte croissance économique, en Grande-Bretagne et en Irlande, pays à faible croissance économique, sur des échantillons d'étudiants mâles d'université. Les résultats ne confirment pas la première hypothèse, mais confirment la seconde.     

Localization of electrocutaneous stimuli on the fingers and forearm: Effects of electrode configuration and body axis

Four experiments were done on the effects of electrode configuration (concentric vs. unifocal) and body axis (longitudinal vs. transverse) on localization of electrocutaneous pulse stimuli at the fingers and forearm. Subjects pointed to the apparent location of current pulses. For the transverse placement of electrodes, pulses were localized correctly, whatever the configuration and the body site might be. In addition, intrasubject variability at the forearm was smaller for the transverse axis than for the longitudinal axis. For the longitudinal placement of electrodes, pulses were localized as a function of configuration and body site. At the fingers, concentric electrodes provided precise localization but unifocal electrodes provided a great mislocalization; and intrasubject variability of localization was larger for the unifocal electrodes than for the concentric electrodes. At the forearm, whatever the configuration might be, the pulses were localized more proximally than the stimulus site; and intrasubject variability of localization did not differ between the configurations. These results are related to Boring’s anchor theory, apparent distance between two points, and the localization of other somatosensory stimuli.