Contrast and spatial variables in texture segregation: testing a simple spatial-frequency channels model

Observers were shown patterns composed of two textures in which each texture contained two types of elements. The elements were arranged in a striped pattern in the top and bottom regions and in a checked pattern in the center region. Observers rated the degree to which the three regions were seen as distinct. When the elements were squares or lines, perceived segregation resulting from differences in element size could be canceled by differences in element contrast. Minimal perceived segregation occurred when the products of the area and the contrast (areal contrasts) of the elements were equal. This dependence of perceived segregation on the areal contrasts of the elements is consistent with a simple model based on the hypothesis that the perceived segregation of the regions is a function of their differential stimulation of spatial-frequency channels. Two aspects of the data were not consistent with quantitative predictions of the model. First, as the size difference between the large and small elements increased, the ratings at the point of minimum perceived segregation increased. Second, some effects of changing the fundamental frequency of the textures were not predicted by the model. These discrepancies may be explained by a more complex model in which a rectification or similar nonlinearity occurs between two stages of orientation- and spatial-frequency-selective linear filters.     

The evolution of leadership during group development

This paper is based on the view that the theory of the group-as-a-whole is illuminated and clarified by a developmental perspective. Beck's theory of group development is used as the framework within which the evolution of four leadership roles across nine developmental phases are discussed. Leadership is defined as a shared function in which four participants play important roles in a dialectical process through which the structure of a group is developed, maintained, reinterpreted or modified as needed. Data are presented on verbal participation and on a sociometric questionnaire to illustrate changes in the four leaders' behavior and the members' perceptions of them across the phases of group development.     

Change blindness blindness: beliefs about the roles of intention and scene complexity in change detection

Observers have difficulty detecting visual changes. However, they are unaware of this inability, suggesting that people do not have an accurate understanding of visual processes. We explored whether this error is related to participants' beliefs about the roles of intention and scene complexity in detecting changes. In Experiment 1 participants had a higher failure rate for detecting changes in an incidental change detection task than an intentional change detection task. This effect of intention was greatest for complex scenes. However, participants predicted equal levels of change detection for both types of changes across scene complexity. In Experiment 2, emphasizing the differences between intentional and incidental tasks allowed participants to make predictions that were less inaccurate. In Experiment 3, using more sensitive measures and accounting for individual differences did not further improve predictions. These findings suggest that adults do not fully understand the role of intention and scene complexity in change detection.     

Simultaneous control of attention by multiple working memory representations

Working memory representations play a key role in controlling attention by making it possible to shift attention to task-relevant objects. Visual working memory has a capacity of three to four objects, but recent studies suggest that only one representation can guide attention at a given moment. We directly tested this proposal by monitoring eye movements while observers performed a visual search task in which they attempted to limit attention to objects drawn in two colors. When the observers were motivated to attend to one color at a time, they searched many consecutive items of one color (long run lengths) and exhibited a delay prior to switching gaze from one color to the other (switch cost). In contrast, when they were motivated to attend to both colors simultaneously, observers' gaze switched back and forth between the two colors frequently (short run lengths), with no switch cost. Thus, multiple working memory representations can concurrently guide attention.     

Childhood Abuse Types and Physical Health at the Age of 24: Testing Health Risk Behaviors and Psychological Distress as Mediators

This study examines whether adult psychological distress and health risk behaviors mediate the relationship between childhood abuse and physical health in adulthood. A randomly selected population-based sample, with oversampling to include a one-third subgroup of former child protection cases, completed a structured interview. Questions pertained to childhood exposure to abuse, adult psychological distress, physical health, and health risk behaviors. Previous research using this sample had identified three abuse typologies: emotional abuse, sexual abuse, and polyvictimization (physical abuse, emotional abuse, and neglect). All three typologies were significantly associated with poorer self-reported physical health. Psychological distress and health risk behaviors partially mediated the relationship between nonabuse, sexual abuse, polyvictimization, and physical health, and fully mediated the relationship between emotional abuse and physical health. The results of this study indicate that health risk behaviors and symptoms of psychological distress could contribute to some of the long-lasting consequences of childhood abuse on adult physical health.     

The development of children's regret and relief

Previous research found that children first experience regret at 5 years and relief at 7. In two experiments, we explored three possibilities for this lag: (1) relief genuinely develops later than regret; (2) tests of relief have previously been artefactually difficult; or (3) evidence for regret resulted from false positives. In Experiment 1 (N=162 4- to 7-year-olds) children chose one of two cards that led to winning or losing tokens. Children rated their happiness then saw a better (regret) or worse (relief) alternative. Children re-rated their happiness. Regret after winning was first experienced at 4, regret after losing and relief after winning were experienced at 5 years and relief after losing at 7 years. Experiment 2 (N=297 5- to 8-year-olds) used a similar task but manipulated children's responsibility for the outcome. Greater responsibility for the outcome resulted in a greater likelihood of an experience of regret and relief. Results support that previous tests of relief were artefactually difficult and regret and relief are experienced earlier than previously thought.     

Combining Information for Quantitative Decision‐making in Drug Development

Taking decisions during the development of a new drug requires combining many and varying pieces of information. The interconnections between these different pieces of information are often only partially known and in some cases merely conjectured. Despite this uncertainty, decisions must be taken – often with regard to the balance of risk and benefit – in order to make progress. A clear, consistent and efficient methodology for describing the structure of a project and the comprehensive state of knowledge at any point in time is required in order to add transparency to the decision process. A viable methodology must allow for a natural characterization of the uncertainty inherent in the drug development process and a relatively easy implementation. We present a possible solution that satisfies these requirements. The foundation of the proposed approach is based on a beta‐binomial update mechanism well known in Bayesian statistics. This work provides a consistent framework for solving hierarchical multicriteria decision problems. Copyright © 2014 John Wiley & Sons, Ltd.