Object and spatial representations in the corner enhancement effect

Cole, Gellatly, and Blurton have shown that targets presented adjacent to geometric corners are detected more efficiently than targets presented adjacent to straight edges. In six experiments, we examined how this corner enhancement effect is modulated by corner-of-object representations (i.e., corners that define an object's shape) and local base-level corners that occur as a result of, for instance, overlapping the straight edges of two objects. The results show that the corner phenomenon is greater for corners of object representations than for corners that do not define an object's shape. We also examined whether the corner effect persists within the contour boundaries of an object, as well as on the outside. The results showed that a spatial gradient of attention accompanies the corner effect outside the contour boundaries of an object but that processing within an object is uniform, with no corner effect occurring. We discuss these findings in relation to space-based and object-based theories of attention.     

Prospective memory and pediatric traumatic brain injury: effects of cognitive demand.

This study investigated the effects of pediatric traumatic brain injury (TBI) on prospective memory. Fourteen children and 14 adolescents with TBI were compared with 25 and 23 noninjured children and adolescents, respectively. Based on a prefrontal model, the cognitive demand on the ongoing component of a prospective-memory task was manipulated. Overall, those with TBI had poorer prospective-memory performance than their noninjured peers. Performance was worse in a high cognitive-demand condition than a low, and younger children performed worse than adolescents. Decreases in performance from the low- to high-demand conditions were not significantly different between the two children's groups but were between the two adolescents' groups. Furthermore, the age and injury effects were reflected in the performances on executive function tests: the Self-ordered Pointing Task (SOPT), and the Stroop Color Word Interference Test. The Tower of London (TOL), which did not produce age or injury effects, was nevertheless found to be an important predictor of performance on the high-demand task in those with TBI. Although previous research has demonstrated impaired prospective memory performance in children with TBI, this study attempted to explain why this might occur, specifically that the prefrontal regions might be implicated.     

Object-based attention is mediated by collinearity of targets

Same-object bias occurs when tasks associated with processing a single object are faster than tasks associated with two objects. Over five experiments we assessed whether same-object bias is mediated by the collinearity of the targets. Participants decided whether two targets, presented either within a single object or across two objects, were the same or different. Results showed that same-object bias only occurred when targets appeared on the same straight line within the same object. When targets appeared in the same object but were separated by an angle or corner, within-object facilitation was eliminated or greatly reduced. In a final experiment, response times to two targets that were collinear but on separate objects were responded to faster than were noncollinear targets on the same object. This suggests that collinearity between targets mediates the effect found in this paradigm, at least to a greater extent than colour grouping.     

Resolving the latent structure of schizophrenia endophenotypes using expectation-maximization-based finite mixture modeling

Prior research has focused on the latent structure of endophenotypic markers of schizophrenia liability, or schizotypy. The work supports the existence of 2 relatively distinct latent classes and derives largely from the taxometric analysis of psychometric values. The present study used finite mixture modeling as a technique for discerning latent structure and the laboratory-measured endophenotypes of sustained attention deficits and eye-tracking dysfunction as endophenotype indexes. In a large adult community sample (N=311), finite mixture analysis of the sustained attention index d' and 2 eye-tracking indexes (gain and catch-up saccade rate) revealed evidence for 2 latent components. A putative schizotypy class accounted for 27% of the sample. A supplementary maximum covariance taxometric analysis yielded highly consistent results. Subjects in the schizotypy component displayed higher rates of schizotypal personality features and an increased rate of treated schizophrenia in their 1st-degree biological relatives compared with subjects in the other component. Implications of these results are examined in light of major theories of schizophrenia liability, and methodological advantages of finite mixture modeling for psychopathology research, with particular emphasis on genomic issues, are discussed.     

LABELING OF ABUSE EXPERIENCES AND RATES OF VICTIMIZATION

Research has consistently found that a history of previous sexual victimization increases risk for future sexual assault, which might be due to women with a history of sexual victimization having difficulty identifying risky cues and not perceiving their own vulnerability for future assaults. This study investigated how acknowledgment of previous experiences with interpersonal violence is related to risk perception and rates of victimization. Participants were 198 college women who completed assessments of victimization, personal risk appraisal, and acknowledgment. Analyses indicated differences in rates of victimization based on labeling of experiences and differences in efforts to change behaviors to reduce risk for future assaults based on level of acknowledgment. Also, there were a number of situational factors significantly related to likelihood of acknowledgment. The findings differed for physical and sexual violence. This study suggests that acknowledgment is an important factor to consider in studies of sexual and physical revictimization.     

Pragmatic Contextualism

Contextualism in epistemology has traditionally been understood as the view that “know” functions semantically like an indexical term, encoding different contents in contexts with different epistemic standards. But the indexical hypothesis about “know” faces a range of objections. This article explores an alternative version of contextualism on which “know” is a semantically stable term, and the truth‐conditional variability in knowledge claims is a matter of pragmatic enrichment. The central idea is that in contexts with stringent epistemic standards, knowledge claims are narrowed: “know” is used in such contexts to make assertions about particularly demanding types of knowledge. The resulting picture captures all of the intuitive data that motivate contextualism while sidestepping the controversial linguistic thesis at its heart. After developing the view, the article shows in detail how it avoids one influential linguistic objection to traditional contextualism concerning indirect speech reports, and then answers an objection concerning the unavailability of certain types of clarification speeches.