Stiffness as a control variable in motor performance

In the experiments described in this article we investigated the control of stiffness of the effector system in relation to parameters of the movement. If the velocity of a movement is chosen, it appears that at the same time the stiffness of the effector system is set to a preferred value. By changing the instruction given to the subject it is possible to change the relationship between velocity and stiffness without changing the kinematic parameters of the movement.Finally, the changes of stiffness and velocity in a learning process are studied. In conformity with what might be expected on intuitive grounds, it is found that velocity increases spontaneously during learning while stiffness decreases. The results are discussed in connection with the generation of motor programmes.     

State capacity,economic policy and world system mobility, 1970–1985

Weak states and ineffective economic policies are assumed to mediate the constraints of the world system and to prevent upward mobility among peripheral countries. This article tests the effects of state strength and economic policy on world system mobility in the period 1970–85 on a sample of 162 countries. World system role and mobility were operationalized using role equivalence based network measures. Countries with effective neoorthodox policies experience significantly higher mobility, even after controlling for economic performance, as do countries with states that have high despotic capacity. No effect, direct or indirect, was found for infrastructural state capacity. Ronan Van Rossem studied sociology at the Free University of Brussels (VUB), Brown University, and Columbia University, and at present is a Senior Researcher at the Division of Child and Adolescent Psychiatry of the New York State Psychiatric Institute in New York City. At present he is involved in a study of the developmental consequences of perinatal brain injury in low birthweight children, and in an evaluation study of ER intervention programs for adolescents who attempt suicide. In his spare time his interests go out to comparative development, political economy, and collective action.     

Self-defining future projections: Exploring the identity function of thinking about the future

The act of projecting oneself into meaningful future events may significantly contribute to a person's sense of self and identity. Yet if the role of memories, in particular self-defining memories (SDMs), in grounding the self is now well established, the identity function of anticipated future events has received comparatively little attention. This article introduces the construct of self-defining future projection (SDFP) to address this issue. Two studies show that people can readily identify significant future events that they frequently think about and that convey core information about who they are as individuals. Furthermore, a person's particular style of constructing SDMs is similarly manifested in SDFPs, suggesting that both types of events can be used to ground the self. Notably, people who display a stronger tendency to extract meaning from their past experiences also reflect more about the potential implications of imagined future events. The results further demonstrate that SDMs and SDFPs both give rise to a strong sense of personal continuity over time and are meaningfully related to self-esteem. Together these findings lend support to the idea that a person's sense of self and identity is in part nourished by the anticipation of significant future events.     

Recruiting Highly Educated Graduates: A Study on the Relationship Between Recruitment Information Sources,the Theory of Planned Behavior,and Actual Job Pursuit

Using the theory of planned behavior, we examined the effects of different recruitment-related information sources on the job pursuit of highly educated graduates. The study was conducted using a real-life longitudinal design. Participants reported on potential employers they were interested in. We used hierarchical linear modeling to analyze within-participant relationships of different information sources with the theory of planned behavior variables, job pursuit behavior, and actual job choice. The theory of planned behavior relationships was supported. Recruitment advertising and positive word of mouth related positively to job pursuit intention and behavior. Negative publicity and word of mouth partly related to job pursuit behavior, indicating their role in the recruitment process. On-campus presence related negatively to job pursuit intention and behavior, suggesting that recruiters should convey parsimonious and realistic job-related information.     

Learning climate scale: Construction,reliability and initial validity evidence

The current study developed an instrument for measuring learning climate in organizations. A review of the organizational learning and facilitation of workplace learning literature resulted in three theoretically relevant dimensions referring to facilitation, appreciation, and error avoidance. The 3-dimensional learning climate scale (LCS) was tested in a heterogeneous sample of Dutch wage earners (N = 1013). Confirmatory factor analysis and analysis of measurement invariance were conducted to establish the factorial structure of the measure. Also, convergent, divergent, and construct validity of the LCS were investigated. The findings showed that the newly developed instrument for learning climate has good psychometric properties: the three-factor structure was supported and the sub-scales were reliable. Furthermore, the LCS showed good convergent and divergent validity.     

Effects of Spatial and Motor Demands in Handwriting

Four experiments were conducted to study response programming in handwriting tasks. Twelve right-handed subjects wrote acoustically presented words and phrases, and their handwriting was digitally recorded. Changes in latency, movement time, trajectory length, and pen pressure were studied as a function of response complexity (i.e., word length, complexity of initial letter, and spacing distance). The lengthening of the spatiotemporal parameters preceding the more complex structures is interpreted to be a reflection of the effects of mental load. The results further indicate that the choice of a programming strategy is dependent on the structural complexity of the task. Writing pressure decreased as a function of increased sequence length. The findings support a hierarchical model of handwriting.     

Global Dominance Outside the Focus of Attention

Identification of the local aspect of a relevant compound stimulus has been found to be delayed by the presence of target-set members at the global aspect of an irrelevant compound stimulus, whereas identification of the global aspect is unaffected by the presence of local target-set members within the irrelevant object (Paquet & Merikle, 1988). This effect has been termed the global category effect , and it suggests that global dominance occurs for objects located outside the attentional focus, as well as within an attended hierarchical object. In the present experiments, attention was directed to the relevant one of two compound stimuli by using either shape information (Experiments 1 and 2) or a 100-msec peripheral rapid onset precue (Experiment 3). Results revealed a global category effect even when the physical features of the displays containing global target-set members within the irrelevant object were closely matched with those of the control displays. Critically, the magnitude of the global category effect was affected by how well attention could be focused on the relevant compound stimulus. These findings suggest (a) that the analysis of global information for irrelevant objects is more elaborate than the simple detection of features; and (b) that both perceptual and attentional mechanisms are involved in global dominance.     

Correspondence analysis of incomplete contingency tables

Correspondence analysis can be described as a technique which decomposes the departure from independence in a two-way contingency table. In this paper a form of correspondence analysis is proposed which decomposes the departure from the quasi-independence model. This form seems to be a good alternative to ordinary correspondence analysis in cases where the use of the latter is either impossible or not recommended, for example, in case of missing data or structural zeros. It is shown that Nora's reconstitution of order zero, a procedure well-known in the French literature, is formally identical to our correspondence analysis of incomplete tables. Therefore, reconstitution of order zero can also be interpreted as providing a decomposition of the residuals from the quasi-independence model. Furthermore, correspondence analysis of incomplete tables can be performed using existing programs for ordinary correspondence analysis.     

Agoraphobia and Locus of Control

This study investigated whether external locus of control, as measured with the Rotter Internal-External Locus of Control Scale, is a specific feature of agoraphobia or whether it characterizes neurosis in general. Forty agoraphobic patients, 81 nonagoraphobic neurotic controls, and 49 normal controls completed the Dutch version of the Rotter Internal-External Locus of Control Scale. Agoraphobic patients were found to have a more external orientation as compared to the normal controls, but as a group, they could not be identified as being different from neurotic controls.This study was supported in part by a grant from the Dutch Organization for Fundamental Research (ZWO/Psychon 560-268-001).