Processing convexity and concavity along a 2-D contour: figure–ground, structural shape, and attention

Interest in convexity has a long history in vision science. For smooth contours in an image, it is possible to code regions of positive (convex) and negative (concave) curvature, and this provides useful information about solid shape. We review a large body of evidence on the role of this information in perception of shape and in attention. This includes evidence from behavioral, neurophysiological, imaging, and developmental studies. A review is necessary to analyze the evidence on how convexity affects (1) separation between figure and ground, (2) part structure, and (3) attention allocation. Despite some broad agreement on the importance of convexity in these areas, there is a lack of consensus on the interpretation of specific claims—for example, on the contribution of convexity to metric depth and on the automatic directing of attention to convexities or to concavities. The focus is on convexity and concavity along a 2-D contour, not convexity and concavity in 3-D, but the important link between the two is discussed. We conclude that there is good evidence for the role of convexity information in figure–ground organization and in parsing, but other, more specific claims are not (yet) well supported.     

Role stressors and exposure to workplace bullying: Causes or consequences of what and why?

Stressful working environments are commonly assumed to create conditions that can lead to bullying. Although environmental factors may relate to both exposure to and perpetration of workplace bullying, empirical knowledge is still limited regarding how environmental factors and bullying is causally linked. In line with interpretations of previous cross-sectional findings, the present study investigated an individual-level target-oriented model of role stressors as antecedents of exposure to workplace bullying, applying a two-wave longitudinal sample of the Norwegian working population. Results from structural regression analyses failed to identify any significant relationships between the role stressors and subsequent exposure to workplace bullying. However, prior exposure to workplace bullying accounted for subsequent variation in role ambiguity, role conflict, and role overload alike. The findings of the present study question conclusions regarding causality made in previous cross-sectional research on work-related factors as antecedents of exposure to workplace bullying. We argue that future research may benefit from adopting multilevel and actor-oriented perspectives in order to more fully understand how causal relationships between environmental factors and workplace bullying unfold.     

Actuarial Criminology: Meeting Current Challenges in Southern Africa

South African prisons were overcrowded by more than sixty-three percent in 2005. Overcrowding and poor prison conditions have enormous implications for rehabilitation efforts made by the South African Department of Correctional Services. The South African White Paper on Corrections (2005) commits the Department of Correctional Services to provide needs-based rehabilitation processes and a framework of continuous evaluation to measure the impact and success of such processes. It also acknowledges that monitoring the rates of recidivism is a critical indicator of the success, the effectiveness of needs-based rehabilitation, and improved service. A reliable system for monitoring recidivism will have to be developed and put in place. In this respect, actuarial criminology can make a vital contribution. This article poses a strategic alternative to the correctional industry in Southern Africa that can be used for the realization of correctional ideals, especially where retribution and overcrowding are still the main features of correctional institutions.     

Logic Games are Complete for Game Logics

Game logics describe general games through powers of players for forcing outcomes. In particular, they encode an algebra of sequential game operations such as choice, dual and composition. Logic games are special games for specific purposes such as proof or semantical evaluation for first-order or modal languages. We show that the general algebra of game operations coincides with that over just logical evaluation games, whence the latter are quite general after all. The main tool in proving this is a representation of arbitrary games as modal or first-order evaluation games. We probe how far our analysis extends to product operations on games. We also discuss some more general consequences of this new perspective for standard logic.     

Self‐perceived competence,learning conceptions and preferred learning situations in the domain of communication

Background: An important purpose of education in the field of social work is the development of social‐communicative competence and students' individual learning theories (ILTs) concerning this domain. Aims: Our first aim was to develop diagnostic instruments for ILT assessment and to understand the relationships between ILT variables. Our second purpose was to study the differences in ILT variables between students of three study years. Samples: A total of 396 full‐time social work students participated in this study: 176 first‐year, 147 second‐year and 73 fourth‐year students (92% women and 8% men). Method: Based on a theoretical framework, three questionnaires have been constructed, covering three ILT variables: self‐perceived competence, learning conceptions and preferred learning situations. For scale construction, principal component analyses and reliability analyses were conducted. ANOVAs and post hoc comparisons of means were used to investigate cross‐sectional differences regarding ILT variables. Pearson correlations and regression analyses were performed to gain more insight into the relationships between ILT variables. Results: Five aspects of self‐perceived competence, four learning conceptions and five preferred learning situations were found. Learning conceptions and self‐perceived competencies were found to be predictors of students' preferred learning situations. Many differences were found between the three groups of students, especially between the first‐year students and the others. Conclusions: When studying the acquisition of social‐communicative competence, it is important to take students' individual learning theories into account. Increased insight into the role ILTs play can be of help in improving social work education.     

Orientational Effects and Component Processes in Symmetry Detection

In previous research on symmetry detection, factors contributing to orientational effects (axis and virtual lines connecting symmetrically positioned dots) and component processes (axis selection and pointwise evaluation) have always been confounded. The reason is the restriction to bilateral symmetry (BS), with pointwise correspondences being orthogonal to the axis of symmetry. In our experiments, subjects had to discriminate random dot patterns from symmetries defined by combining 12 axis orientations (every 15°) with seven reflection angles (0°, yielding BS, and three clockwise and counterclockwise 15° steps, yielding skewed symmetry, SS). In Experiment 1, with completely randomized trial order, a significant interaction between axis and skewing angle was obtained, indicating that classically observed orientational effects are restricted to BS and that the orientation of the pointwise correspondences is important. These basic findings were replicated in three subsequent experiments, which differed in that they used blocks containing patterns with the same axis (Experiment 2), virtual lines orientation (Experiment 3), or their combination (Experiment 4). Based on a comparison between the results obtained by these manipulations, we suggest a possible reason for the failure of preattentive symmetry detection in the case of dot patterns with SS.     

Inconsistencies in extensive games

In certain finite extensive games with perfect information, Cristina Bicchieri (1989) derives a logical contradiction from the assumptions that players are rational and that they have common knowledge of the theory of the game. She argues that this may account for play outside the Nash equilibrium. She also claims that no inconsistency arises if the players have the minimal beliefs necessary to perform backward induction. We here show that another contradiction can be derived even with minimal beliefs, so there is no paradox of common knowledge specifically. These inconsistencies do not make play outside Nash equilibrium plausible, but rather indicate that the epistemic specification must incorporate a system for belief revision. Whether rationality is common knowledge is not the issue.