Motor sequence learning performance in Parkinson's disease patients depends on the stage of disease

It is still unclear, whether patients with Parkinson's disease (PD) are impaired in the incidental learning of different motor sequences in short succession, although such a deficit might greatly impact their daily life. The aim of this study was thus to clarify the relation between disease parameters of PD and incidental motor learning of two different sequences in short succession. Results revealed that the PD patients were able to acquire two sequences in short succession but needed more time than healthy subjects. However, both the severity of axial manifestations, as assessed on a subsection of the Unified Parkinson's Disease Rating Scale III (UPDRS III) and the Hoehn and Yahr score, and the levodopa-equivalent dose (LED) were negatively correlated with the sequence learning performance. These findings indicate that, although PD patients are able to learn two sequences in short succession, they need more time and their overall sequence learning performance is strongly correlated with the stage of disease.     

Gender Bias in Leader Selection? Evidence from a Hiring Simulation Study

The present research investigated factors that might affect gender discrimination in a hiring simulation context from the perspectives of social role theory and the shifting standards model. Specifically, the experimental study investigated whether gender biases are evident in the screening and hiring stage of the personnel selection process depending on the applicants?? social role and evaluators?? gender. A sample of German undergraduate business students (54 women, 53 men) was asked to make a personnel selection decision (short-listing or hiring) about a fictitious applicant (man or woman) in a specific role (leader or non-leader) for a managerial position. Consistent with social role theory??s assumption that social role information is more influential than gender information, participants selected applicants described as leaders over applicants described as non-leaders, regardless of applicant gender. In addition, in the presence of role information, female applicants portrayed as leaders were similarly short-listed and hired as male applicants with the same credentials. In the absence of role information, female applicants were similarly short-listed as male applicants; however, male applicants were hired over female applicants, albeit by male participants only. This is consistent with the shifting standards model??s assumption that group members are held to a higher standard to confirm traits on which they are perceived to be deficient: Male participants hired female applicants portrayed as non-leaders with less certainty than their male counterparts possibly due to higher confirmatory standards for leadership ability in women than men. The research and practice implications of these results are discussed.     

Time-course of feature-based top-down control in saccadic distractor effects

Saccadic reaction time (SRT) is more strongly slowed by target-similar than dissimilar distractors (similarity effect). The time course of this similarity effect was investigated by varying target contrast and analyzing SRT distributions. With foveal distractors, the similarity effect increased with increasing SRT, suggesting that top-down enhancement of target features increased over time. This allowed for successful saccades to the peripheral target, but also entailed larger distraction by target-similar stimuli. Similarity effects with peripheral distractors did not increase with SRT, which we attribute to location-based inhibition containing the growing enhancement of target features. Strong inhibition was likely with peripheral distractors because they always appeared at the same task-irrelevant location. Prior inhibition with foveal distractors was weaker because this would have partially released fixation and entailed anticipations.     

Hindsight bias in gustatory judgments

Being in hindsight, people tend to overestimate what they had known in foresight. This phenomenon has been studied for a wide variety of knowledge domains (e.g., episodes with uncertain outcomes, or solutions to almanac questions). As a result of these studies, hindsight bias turned out to be a robust phenomenon. In this paper, we present two experiments that successfully extended the domain of hindsight bias to gustatory judgments. Participants tasted different food items and were asked to estimate the quantity of a certain ingredient, for example, the residual sugar in a white wine. Judgments in both experiments were systematically biased towards previously presented low or high values that were labeled as the true quantities. Thus, hindsight bias can be considered a phenomenon that extends well beyond the judgment domains studied so far.     

Translating visual information into action predictions: Statistical learning in action and nonaction contexts

Humans are sensitive to the statistical regularities in action sequences carried out by others. In the present eyetracking study, we investigated whether this sensitivity can support the prediction of upcoming actions when observing unfamiliar action sequences. In two between-subjects conditions, we examined whether observers would be more sensitive to statistical regularities in sequences performed by a human agent versus self-propelled ‘ghost’ events. Secondly, we investigated whether regularities are learned better when they are associated with contingent effects. Both implicit and explicit measures of learning were compared between agent and ghost conditions. Implicit learning was measured via predictive eye movements to upcoming actions or events, and explicit learning was measured via both uninstructed reproduction of the action sequences and verbal reports of the regularities. The findings revealed that participants, regardless of condition, readily learned the regularities and made correct predictive eye movements to upcoming events during online observation. However, different patterns of explicit-learning outcomes emerged following observation: Participants were most likely to re-create the sequence regularities and to verbally report them when they had observed an actor create a contingent effect. These results suggest that the shift from implicit predictions to explicit knowledge of what has been learned is facilitated when observers perceive another agent’s actions and when these actions cause effects. These findings are discussed with respect to the potential role of the motor system in modulating how statistical regularities are learned and used to modify behavior.     

Modeling competence development in the presence of selection bias

A major challenge for representative longitudinal studies is panel attrition, because some respondents refuse to continue participating across all measurement waves. Depending on the nature of this selection process, statistical inferences based on the observed sample can be biased. Therefore, statistical analyses need to consider a missing-data mechanism. Because each missing-data model hinges on frequently untestable assumptions, sensitivity analyses are indispensable to gauging the robustness of statistical inferences. This article highlights contemporary approaches for applied researchers to acknowledge missing data in longitudinal, multilevel modeling and shows how sensitivity analyses can guide their interpretation. Using a representative sample of N = 13,417 German students, the development of mathematical competence across three years was examined by contrasting seven missing-data models, including listwise deletion, full-information maximum likelihood estimation, inverse probability weighting, multiple imputation, selection models, and pattern mixture models. These analyses identified strong selection effects related to various individual and context factors. Comparative analyses revealed that inverse probability weighting performed rather poorly in growth curve modeling. Moreover, school-specific effects should be acknowledged in missing-data models for educational data. Finally, we demonstrated how sensitivity analyses can be used to gauge the robustness of the identified effects.