Context-specific control and context selection in conflict tasks

This study investigated whether participants prefer contexts with relatively little cognitive conflict and whether this preference is related to context-specific control. A conflict selection task was administered in which participants had to choose between two categories that contained different levels of conflict. One category was associated with 80% congruent Stroop trials and 20% incongruent Stroop trials, while the other category was associated with only 20% congruent Stroop trials and 80% incongruent Stroop trials. As predicted, participants selected the low-conflict category more frequently, indicating that participants avoid contexts with high-conflict likelihood. Furthermore, we predicted a correlation between this preference for the low-conflict category and the control implementation associated with the categories (i.e., context-specific proportion congruency effect, CSPC effect). Results however did not show such a correlation, thereby failing to support a relationship between context control and context selection.     

Determining sociability, social space, and social presence in (a)synchronous collaborative groups.

The effectiveness of group learning in asynchronous distributed learning groups depends on the social interaction that takes place. This social interaction affects both cognitive and socioemotional processes that take place during learning, group forming, establishment of group structures, and group dynamics. Though now known to be important, this aspect is often ignored, denied or forgotten by educators and researchers who tend to concentrate on cognitive processes and on-task contexts. This "one-sided" educational focus largely determines the set of requirements in the design of computer-supported collaborative learning (CSCL) environments resulting in functional CSCL environments. In contrast, our research is aimed at the design and implementation of sociable CSCL environments which may increase the likelihood that a sound social space will emerge. We use a theoretical framework that is based upon an ecological approach to social interaction, centering on the concept of social affordances, the concept of the sociability of CSCL environments, and social presence theory. The hypothesis is that the higher the sociability, the more likely that social interaction will take place or will increase, and the more likely that this will result in an emerging sound social space. In the present research, the variables of interest are sociability, social space, and social presence. This study deals with the construction and validation of three instruments to determine sociability, social space, and social presence in (a)synchronous collaborating groups. The findings suggest that the instruments have potential to be useful as measures for the respective variables. However, it must be realized that these measures are "first steps."     

Sustained suppression in congruency tasks

In a list version of the Stroop task, Thomas (1977) observed that Stroop interference was smaller when the irrelevant word was repeated through parts of the list. MacLeod (1991) formulated the sustained-suppression hypothesis for this effect. It is assumed that the automatic response activation on the basis of the irrelevant word is selectively suppressed. In this paper this hypothesis is further investigated. In a serial Stroop task with short response-stimulus interval (RSI) we demonstrate that the Stroop effect disappears when the irrelevant word is repeated, whereas the Stroop effect is evident when the word changes. With a long RSI, there is no influence of the sequence of the irrelevant word. The same pattern of results is observed in a flanker task. The results are discussed in terms of the activation-suppression model (Ridderinkhof, 2002) and the sustained-suppression hypothesis.     

Effects of LMX and differential treatment on work unit commitment

The Leader-Member exchange (LMX) theory of leadership states that leaders do behave differently towards the various members in their work unit. Relatively little attention has been devoted to the question of whether members' perceptions of differential treatment on the part of the leader affects their commitment to the work unit. Perceptions of the amount of differential treatment within their work unit did not explain additional variance in members' work unit commitment after the effects of LMX quality were accounted for. There was, however, a significant interaction effect of LMX quality and differential treatment on work unit commitment. The perception of a large number of differential treatment incidents seems to act as a neutralizer with respect to the positive effects LMX quality may have.     

Parametric and nonparametric bootstrap methods for meta-analysis

In a meta-analysis, the unknown parameters are often estimated using maximum likelihood, and inferences are based on asymptotic theory. It is assumed that, conditional on study characteristics included in the model, the between-study distribution and the sampling distributions of the effect sizes are normal. In practice, however, samples are finite, and the normality assumption may be violated, possibly resulting in biased estimates and inappropriate standard errors. In this article, we propose two parametric and two nonparametric bootstrap methods that can be used to adjust the results of maximum likelihood estimation in meta-analysis and illustrate them with empirical data. A simulation study, with raw data drawn from normal distributions, reveals that the parametric bootstrap methods and one of the nonparametric methods are generally superior to the ordinary maximum likelihood approach but suffer from a bias/precision tradeoff. We recommend using one of these bootstrap methods, but without applying the bias correction.     

Effects of stimulus-stimulus compatibility and stimulus-response compatibility on response inhibition

Previous studies demonstrated that interference control in stimulus–stimulus compatibility tasks slowed down stopping in the stop signal task (e.g., Kramer, A. F., Humphrey, D. G., Larish, J. F., Logan, G. D., & Strayer, D. L. (1994). Aging and inhibition: beyond a unitary view of inhibitory processing in attention. psychology and aging, 9, 491–512). In the present study, the impact of stimulus–stimulus compatibility and stimulus–response compatibility on response inhibition is further investigated. In Experiment 1, the stop signal task was combined with a traditional horizontal Simon task and with a vertical variant. For both dimensions, stopping responses was prolonged in incompatible trials, but only when the previous trial was compatible. In Experiment 2, the Simon task was combined with a spatial Stroop task in order to compare the effects of stimulus–stimulus and stimulus–response compatibility. The results demonstrated that both types of compatibility influenced stopping in a similar way. These findings are in favor of the hypothesis that response inhibition in the stop signal task and interference control in conflict tasks rely on similar mechanisms.     

Administrative Obedience: Carrying Out Orders to use Psychological-Administrative Violence

A paradigm named ‘administrative obedience’ was designed to study obedience in carrying out orders to use a kind of violence that is typical for our times, namely psychological-administrative violence resulting in definite harm. In this study, the victim was an applicant for a job, who came to the laboratory to take a test, This test would determine whether or not he would get the job. Subjects were ordered, in the context of a research project, to make the applicant nervous and to disturb him during the test; consequently, the applicant failed the test and remained unemployed. More than 90 per cent of the subjects carried out these orders, although they considered them unfair and did not enjoy doing the task, The level of administrative obedience found in our study is higher than the level of obedience found in the comparable experiment by Milgram. The experimental conditions ‘Experimental absent’ and ‘Two peers rebel’ produced a reduction of obedience in our paradigm comparable to that which occurred in Milgram's paradigm.