Achievement in mathematics in grades 9 and 11 in Limpopo Province of South Africa: introduction of a problem-based approach

800 students in Grades 9 and 11 of schools in the Central Region of the Limpopo Province of South Africa completed the Study Orientation Questionnaire in Mathematics. Mean age in Grade 11 was 17.5 yr. (SD = 1.4) and in Grade 9 15.1 yr. (SD = 1.2). Intervention was aimed at teachers and students in this group. Teachers in the trained group received training in a problem-based approach to teaching and learning in mathematics and introduced these principles into their classes. Analysis of variance on the differences between post- and pretest scores of the six subscales and the marks in mathematics and English yielded no effects for grade, sex, or grade after 6 mo. Pearson correlations for students in Grade 11 were positive between study orientation and achievement in mathematics. Improving teachers' training and expertise, transforming disadvantaged learning environments, and developing necessary formal and informal mathematical knowledge seem both essential and difficult.     

Information along contours and object boundaries

F. Attneave (1954) famously suggested that information along visual contours is concentrated in regions of high magnitude of curvature, rather than being distributed uniformly along the contour. Here the authors give a formal derivation of this claim, yielding an exact expression for information, in C. Shannon's (1948) sense, as a function of contour curvature. Moreover, they extend Attneave's claim to incorporate the role of sign of curvature, not just magnitude of curvature. In particular, the authors show that for closed contours, such as object boundaries, segments of negative curvature (i.e., concave segments) literally carry greater information than do corresponding regions of positive curvature (i.e., convex segments). The psychological validity of this informational analysis is supported by a host of empirical findings demonstrating the asymmetric way in which the visual system treats regions of positive and negative curvature.     

Contraction bias in memorial quantifying judgment: does it come from a stable compressed memory representation or a dynamic adaptation process?

A common response bias in psychophysical judgments is regression toward the mean (overestimation of small and underestimation of large values, or the response contraction bias). The same bias is observed in magnitude estimation from memorized quantities. Participants estimated alphabetic interval distances between 2 letters for different levels of interletter distances. The underestimated and overestimated values and the point of least error changed, depending on the level of alphabetic distances judged; furthermore, their estimation showed a progressively increasing tendency toward the mean, rendering the estimation progressively less accurate as the estimation task was repeated. We conclude that the regression toward the mean in memorial quantifying judgment derives from a cognitive adaptation process rather than from a permanent, compressed memory representation of the stimuli. Two opposing views on the adaptive meaning of this judgment bias are discussed.     

Visual identification and spatial location in Alzheimer's disease

Twelve patients with Alzheimer's disease (AD) and 15 healthy elderly control subjects were shown sets of luminance-defined letters, texture-defined letters, luminance-defined squares, and texture-defined squares. They were asked to name the letters or point to the target square on each page. The stimuli were graded into four levels of difficulty based on the amount of contrast between the figure and the background. Performance was measured in terms of the maximum level of difficulty at which the participant correctly identified or located the three figures. Contrary to expectations, no significant difference was found between the performance of AD patients and control subjects on texture discrimination tasks vs. luminance discrimination tasks. However, results indicate that AD patients are impaired in performing a task requiring them to locate a texture-defined target of known shape in a noisy background field. By contrast, AD patients show no significant deficit in a task requiring them to locate a texture-defined shape in a known location. This argues that the observed deficit in the location task is not due to a failure in the system that discriminates target texture from background texture (since both location and identification tasks require the same textural discriminations), but rather to an impairment of the system responsible for "finding things" (i.e., locating known targets at unknown locations). This observation suggests that AD patients may suffer selective damage to the dorsal "Where" pathway, which is responsible for localizing objects in space.     

The impact of rock videos and music with suicidal content on thoughts and attitudes about suicide

In Experiment 1, 133 college student volunteers watched a rock music video with or without suicidal content and then completed written measures assessing mood, priming of suicide-related thoughts, perceptions of personal risk, sensitivity to suicidality in others, and attitudes/beliefs about suicide. In Experiment 2, 104 college student volunteers listened to rock music with either suicidal or neutral content and then completed measures similar to Experiment 1, with the addition of a hopelessness measure. In both experiments, participants exposed to suicidal content wrote more scenarios with suicide-related themes in a projective storytelling task than those exposed to nonsuicidal content. However, there were virtually no group differences on explicit measures of affect, attitudes, and perceptions. Music and videos with suicide content appeared to prime implicit cognitions related to suicide but did not affect variables associated with increased suicide risk.     

Influences of Marital Conflict on Child Adjustment: Review of Theory and Research

This review summarizes the literature on the relationship between marital conflict and child maladjustment with an emphasis on variables that qualify, explain the association, or both. Following a historical review, the modest findings on the strength of the association between marital conflict and child maladjustment is explored. The definition of marital conflict is clarified through specification of its various dimensions (frequency, intensity, content, resolution). The role of variables that serve to moderate and/or mediate the relationship between marital conflict and child maladjustment are elaborated. Mediating models include exposure theories (Modeling, Cognitive–Contextual effects: appraisal of threat and blame, and Emotional Insecurity) and changes in the parent–child relationship (Spillover). Variables that moderate or qualify the relationship include children's cognitions and behaviors, contextual factors, and demographic differences. A model is presented summarizing these mechanisms. Research recommendations are proposed and the clinical implications of this literature are addressed.