Spinal Cord Circuits

Over the past decade, research at three different levels of sensorimotor control has revealed a degree of complexity that challenges traditional hypotheses regarding servocontrol of individual muscles: (a) The connectivity of spinal circuits is much more divergent and convergent than expected. (b) The normal and reflex-induced recruitment of individual muscles and compartments of muscles is more finely controlled than was noted previously. (c) The mechanical interactions among linked skeletal segments and their often multiarticular muscles are neither simple nor intuitively obvious. We have developed a mathematical model of the cat hind limb that permits us to examine the influence of individual muscles on posture and gait. We have used linear quadratic control theory to predict the optimal distribution of feedback from a hypothetical set of proprioceptors, given different assumptions about the behavioral goals of the animal. The changes in these predictions that result from changes in the structure and control objectives of the model may provide insights into the functions actually performed by the various circuits in the spinal cord.     

The Anatomy of Disappointment: A Naturalistic Test of Appraisal Models of Sadness,Anger, and Hope

Vignette and autobiographical recall studies have often been used to test models of the appraisals associated with specific emotions. Recently, critiques of both methodologies have called into question the applicability of appraisal theory to naturally-occurring emotional responses. This study examined supporter's responses to Ross Perot's withdrawal from the 1992 presidential race to assess the extent to which appraisal models accurately capture responses to a naturally-occurring event. Supporters in Riverside County, California (N = 227) completed questionnaires concerning their interpretations of the event, their initial emotional reactions, changes in their reactions in the weeks immediately following Perot's withdrawal, and their plans. Appraisal models correctly predicted the dimensions of agency and coping potential that served to differentiate sadness from anger, and the appraisals and plans associated with hope. Appraisal models did not predict the strong focus of sad supporters on their past goals and beliefs, and the plans associated with sadness and anger. Changes in emotional intensity occurred as a function of changes in goals and plans rather than merely as a function of time. These findings demonstrate the applicability of appraisal theory to naturally-occurring emotional responses, but also show that models may understate the complexity of the planning processes associated with emotions.     

On Russell's vulnerability to Russell's paradox

Influenced by G. E. Moore, Russell broke with Idealism towards the end of 1898; but in later years he characterized his meeting Peano in August 1900 as ‘the most important event’ in ‘the most important year in my intellectual life’. While Russell discovered his paradox during his post-Peano period, the question arises whether he was already committed, during his pre-Peano Moorean period, to assumptions from which his paradox may be derived. Peter Hylton has argued that the pre-Peano Russell was thus vulnerable to (at least one version of) Russell's paradox and hence that the paradox exposes a pre-existing difficulty in Russell's Moorean philosophy. Contrary to Hylton, I argue that the Moorean Russell adhered to views which insulated him against the paradox. Further, I argue that Russell became vulnerable to his paradox as a result of changes in his Moorean position occasioned, first, by his acceptance of Cantor's theory of the transfinite, and, second, by his correspondence with Frege. I conclude with some general comments regarding Russell's acceptance of naïve set theory.     

Visual image retention does not contribute to modulation of event-related potentials by mental rotation

Rotation of a visual image in mind is associated with a slow posterior negative deflection of the event-related potential (ERP), termed rotation-related negativity (RRN). Retention of a visual image in short-term memory is also associated with a slow posterior negative ERP, termed negative slow wave (NSW). We tested whether short-term memory retention, indexed by the NSW, contributes to the RRN. ERPs were recorded in the same subjects in two tasks, a mental rotation task, eliciting the RRN, and a visual short-term memory task, eliciting the NSW. Over both right and left parietal scalp, no association was found between the NSW and the RRN amplitudes. Furthermore, adjusting for the effect of the NSW had no influence on a significant association between the RRN amplitude and response time, an index of mental rotation performance. Our data indicate that the RRN reflects manipulation of a visual image but not its retention in short-term memory.     

The Contribution of Executive Skills to Reading Comprehension

Although word recognition deficits (WRD) are a known cause of reading comprehension deficits (RCD), other contributions to RCD, including executive function (EF), have not been fully explored. We examined the contribution of EF (working memory and planning), along with attention, decoding, fluency, and vocabulary to reading comprehension in 60 children (including 16 WRD and 10 RCD), ages 9–15 years. After controlling for commonly accepted contributors to reading comprehension (i.e., attention, decoding skills, fluency, and vocabulary), EF continued to make a significant contribution to reading comprehension but not to word recognition skills. These findings highlight the need for consideration of the role of EF in RCD.     

Anxiety's role in aids prevention

Abstract

Anxiety's role in AIDS risk reduction is discussed. We argue that behavioral techniques will be critical tools for alerting people to the threat of AIDS and their own vulnerability. Informational models have not been found to be sufficient for convincing people of the extent of the threat of AIDS to them. We suggest that techniques aimed at raising people's anxiety over their vulnerability will be necessary to raise their motivation to attend to AIDS messages, and we present techniques aimed at increasing anxiety over vulnerability. Following acknowledgment of vulnerability, people will need to adopt or continue safer sex practices that are viewed as undesirable in contrast to unsafe sex practices that are viewed as less costly and less anxiety provoking. Given a clearer practical and theoretical understanding of the anxiety-producing costs of adopting safer sex behaviors, we present methods for reducing this anxiety. We also discuss the necessity for considering ethnic, minority, and other cultural nuances in social and sexual anxiety and how these might be addressed in efforts to increase safer sex practices.     

The role of body image in the prevention of eating disorders

This article reviews theory and research pertaining to prevention of negative body image and eating disorders. Research derived from the social cognitive model (SCM) and non-specific vulnerability-stressor (NSVS) model indicates that sustained prevention effects for attitudes and behaviors are possible, but not easy to achieve or explain. These limitations are considered in the context of promising research derived from a third model, critical social perspectives (CSP). We conclude that (1) research on practice should aim beyond the examination of efficacy in order to clarify the active ingredients contributing to prevention; and (2) research informed by each of the divergent perspectives can be used to enrich theory and practice in the field of eating disorders prevention.     

Diagnostic Utility: Experimental Demonstrations and Replications of Powerful Question Effects in High‐Stakes Deception Detection

The concept of diagnostic utility was used to create questions that would differentially affect deception detection accuracy. Six deception detection studies show that subtle differences in questioning produced accuracy rates that were predictably, substantially, and reliably above and below chance. The first 3 detection studies demonstrate that diagnostically useful questioning can reliably achieve accuracy rates over 70% with student and experienced judges. The fourth and fifth experiments demonstrated negative diagnostic utility among federal investigators but not students. The final experiment crossed 3 sets of interview questions with experience. Strong question effects produced a swing in accuracy from 32 to 73%. A questioning by experience interaction was also obtained.