Disentangling the relationship between hemispheric asymmetry and cognitive performance

It is widely believed that advantages of hemispheric asymmetries originated in better cognitive processing, hence it is often implied that the relationship between hemispheric asymmetry and cognitive performance is linearly positive: the higher the degree of lateralization in a specific cognitive domain, the better the performance in a corresponding task. Yet, the empirical evidence for this notion is mixed and the statistical methods to analyze this relationship have been criticized. The present study therefore investigated the relationship between hemispheric asymmetries and cognitive performance in two behavioral tasks (a left-lateralized word-matching task and a right-lateralized face-decision task) in 230 participants (140 women, 90 men) by using two different approaches. Both methods correspondingly revealed that a relationship between hemispheric asymmetries and cognitive performance does exist. Contrary to a positive (linear) relationship however, the data could be best described by an inverted U-shaped curve. Although the optimal degree of lateralization seemed to be task-specific, a slight or moderate degree of hemispheric asymmetry achieved best cognitive performance in all tasks. Moreover, performances deteriorated towards extreme ends of lateralization (i.e., participants with either extreme left or right hemispheric biases). Taken together, the present study provides evidence against the notion that higher lateralization is related to enhanced cognitive performance.     

Beneficial Effect of Pictures on False Memory in the DRMRS Procedure

Using the Deese-Roediger-McDermott-Read-Solso (DRMRS) procedure in which list items are shown that are semantically related to a central theme that is not presented, undergraduates (N?=?61) studied either short or long lists in the form of auditory words alone, pictures alone, or pictures accompanied by auditory words. Correct recall and correct recognition scores were similar in all three conditions. However, false memory (reporting the non-presented central theme) was reduced with pictures alone compared to words alone for the recall task, and for the recognition task with short lists. Confidence was higher for correct recall and correct recognition than for false recall and false recognition, but people who were higher or lower in confidence did not differ on any memory measure. Theoretical and practical implications of these results are discussed.     

The Use of Propensity Scores in Mediation Analysis

Mediation analysis uses measures of hypothesized mediating variables to test theory for how a treatment achieves effects on outcomes and to improve subsequent treatments by identifying the most efficient treatment components. Most current mediation analysis methods rely on untested distributional and functional form assumptions for valid conclusions, especially regarding the relation between the mediator and outcome variables. Propensity score methods offer an alternative whereby the propensity score is used to compare individuals in the treatment and control groups who would have had the same value of the mediator had they been assigned to the same treatment condition. This article describes the use of propensity score weighting for mediation with a focus on explicating the underlying assumptions. Propensity scores have the potential to offer an alternative estimation procedure for mediation analysis with alternative assumptions from those of standard mediation analysis. The methods are illustrated investigating the mediational effects of an intervention to improve sense of mastery to reduce depression using data from the Job Search Intervention Study (JOBS II). We find significant treatment effects for those individuals who would have improved sense of mastery when in the treatment condition but no effects for those who would not have improved sense of mastery under treatment.     

Persistent effects of information about internal reactions: Ineffectiveness of debriefing

A process of self-persuasion has been advanced to account for the effects of information about internal reactions on attitudes toward emotional stimuli. To determine whether the results of this cognitive activity would be resistant to debriefing, Ss were shown slides of female nudes while hearing their alleged heart-rate reactions and were subsequently informed that these reactions were part of a deception manipulation. It was found that, although Ss accepted the debriefing, the false information continued to exert an infleunce on their attitudes toward the nudes. The attitudes of these Ss toward the nudes were the same as those of Ss who were not debriefed.     

Negative Affect in Victimized Children: The Roles of Social Withdrawal, Peer Rejection, and Attitudes Toward Bullying

This study evaluated the validity of mediating pathways in predicting self-assessed negative affect from shyness/social withdrawal, peer rejection, victimization by peers (overt and relational), and the attitude that aggression is legitimate and warranted. Participants were 296 3rd through 5th graders (156 girls, 140 boys) from 10 elementary schools. Self-report measures of victimization, attitudes, and negative affect, and a teacher-report measure of shyness/social withdrawal and peer rejection were completed during the spring semesters of 2 consecutive years. Hierarchical regression analyses supported the mediational model in predicting negative affect at Time 2. However, an increase in negative affect over the 12-month study period was best accounted for by direct effects of increased victimization and changes in attitudes/attributions regarding aggression. Implications for the planning of school interventions designed to interrupt these victimization-maladjustment pathways are discussed.     

An examination of learning processes during critical incident training: implications for the development of adaptable trainees

Three experiments are reported that examined the process by which trainees learn decision-making skills during a critical incident training program. Formal theories of category learning were used to identify two processes that may be responsible for the acquisition of decision-making skills: rule learning and exemplar learning. Experiments 1 and 2 used the process dissociation procedure (L. L. Jacoby, 1998) to evaluate the contribution of these processes to performance. The results suggest that trainees used a mixture of rule and exemplar learning. Furthermore, these learning processes were influenced by different aspects of training structure and design. The goal of Experiment 3 was to develop training techniques that enable trainees to use a rule adaptively. Trainees were tested on cases that represented exceptions to the rule. Unexpectedly, the results suggest that providing general instruction regarding the kinds of conditions in which a decision rule does not apply caused them to fixate on the specific conditions mentioned and impaired their ability to identify other conditions in which the rule might not apply. The theoretical, methodological, and practical implications of the results are discussed.     

A Bayesian prediction of four-look recognition performance from one-look data

The hypothesis that a human O’s (S’s) performance in a visual recognition task can be modelled by Bayes’ theorem was investigated. Two Ss were run for 40 experimental sessions each. Their task was to specify the direction of the gap of tachistoscopically presented Landolt rings (Cs). There were four possible gap directions, and two experimental conditions. In one condition, S responded after each stimulus presentation. In the other, a fixed-observation condition, Ss responded after four consecutive presentations of a C. Exposure durations were such that performance under both conditions was greater than chance, but less than unity. Predictions of four-look performance from one-look data were made. Overall hit rates were predicted closely. The entire pattern of each S’s four-look data was also predicted reasonably well. Further tests of the model are currently under way.     

Inter-digital variability in the palmer sweat indices of adult stutterers

This study examined the relationship of mean palmar sweat density of all fingers of each hand, thumbs excluded, to asymetrical interdigital sweat variability in adult stutterers. In addition, the relationship of mean print density to part word repetitions and prolongations was investigated.

A modification of the palmar sweat printer developed by Brutten (1957) enabling the accommodation of eight fingers, was employed to obtain simultaneous PSI under identical controlled conditions for all fingers.

Results indicated that the eight fingers are not reliable areas for the determination of palmar sweating in adult stutterers. Consequently, the PSI as it is currently employed, as well as the method used in the present study, does not appear to be an acceptable objective measure of ANS arousal in adult stutterers.