A System of Axioms for Minkowski Spacetime

Journal of Philosophical Logic - We present an elementary system of axioms for the geometry of Minkowski spacetime. It strikes a balance between a simple and streamlined set of axioms and the...     

Attentional Processing of Threat in Bipolar Disorder: Going Beyond Mood-Congruency

Emotional processing in bipolar disorder (BD) entails a complex attentional pattern not merely restricted to happy or sad biases, but also directed towards threatening information. This study examined threat-related bias on attentional orienting when participants were not instructed about the presentation of emotional stimuli (i.e., implicit instructions). An emotional dot-probe task in which an emotional face (i.e., threat, sad, happy) is simultaneously displayed with a neutral face was applied to BD individuals in their different episodes: mania (n?=?26), depression (n?=?24), and euthymia (n?=?28) as well as to a group of healthy controls (n?=?28). Symptomatic BD patients (i.e., in a manic or depressive episode) showed an attentional orienting bias toward threatening faces but not for happy or sad faces, while euthymic BD patients did not exhibit any attentional bias for emotional stimuli. A bias toward happy faces was found in the control group. Threat-related bias was not related to the severity of affective and anxiety symptoms in BD. When attention is not explicitly directed to emotional information, threat-related bias may characterize attentional orienting during mania and depression, but may be attenuated during euthymia.

     

The Relationship of Appetitive, Reproductive and Posterior Pituitary Hormones to Alcoholism and Craving in Humans

A significant challenge for understanding alcoholism lies in discovering why some, but not other individuals, become dependent on alcohol. Genetic, environmental, cultural, developmental, and neurobiological influences are recognized as essential factors underlying a person's risk for becoming alcohol dependent (AD); however, the neurobiological processes that trigger this vulnerability are still poorly understood. Hormones are important in the regulation of many functions and several hormones are strongly associated with alcohol use. While medical consequences are important, the primary focus of this review is on the underlying confluence of appetitive/feeding, reproductive and posterior pituitary hormones associated with distinct phases of alcoholism or assessed by alcohol craving in humans. While these hormones are of diverse origin, the involvement with alcoholism by these hormone systems is unmistakable, and demonstrates the complexity of interactions with alcohol and the difficulty of successfully pursuing effective treatments. Whether alcohol associated changes in the activity of certain hormones are the result of alcohol use or are the result of an underlying predisposition for alcoholism, or a combination of both, is currently of great scientific interest. The evidence we present in this review suggests that appetitive hormones may be markers as they appear involved in alcohol dependence and craving, that reproductive hormones provide an example of the consequences of drinking and are affected by alcohol, and that posterior pituitary hormones have potential for being targets for treatment. A better understanding of the nature of these associations may contribute to diagnosing and more comprehensively treating alcoholism. Pharmacotherapies that take advantage of our new understanding of hormones, their receptors, or their potential relationship to craving may shed light on the treatment of this disorder.     

Mathematical Models of Central Pattern Generators in Locomotion

Possible neural connective patterns and functions with respect to interlimb coordination are studied theoretically with a mathematical model of the central pattern generating system for cat locomotion. Activities in populations of neurons controlling limb joint flexors and extensors in all four limbs are represented by a system of nonlinear differential equations. Solutions of the system for various parameter values simulate various gaits of the cat. The model is shown to be capable of generating all gaits of the cat and accounting for corresponding phase changes in interlimb coordination. The model also exhibits smooth changes of gait, and smooth initiation and termination of stepping. Further, within each limb, muscle sequencing, step cycle phases, and flexor-extensor interactions can be studied. The model suggests that one of the simplest mechanisms for a central command system to change the gait is via inhibition of specific interlimb propriospinal pathways. In a final section, properties of both proposed single limb and interlimb models are reviewed with specific reference to planning future experimental and theoretical studies.     

Piéron's Law holds during stroop conflict: insights into the architecture of decision making

Piéron's Law describes the relationship between stimulus intensity and reaction time. Previously (Stafford & Gurney, 2004), we have shown that Piéron's Law is a necessary consequence of rise-to-threshold decision making and thus will arise from optimal simple decision-making algorithms (e.g., Bogacz, Brown, Moehlis, Holmes, & Cohen, 2006). Here, we manipulate the color saturation of a Stroop stimulus. Our results show that Piéron's Law holds for color intensity and color-naming reaction time, extending the domain of this law, in line with our suggestion of the generality of the processes that can give rise to Piéron's Law. In addition, we find that Stroop condition does not interact with the effect of color saturation; Stroop interference and facilitation remain constant at all levels of color saturation. An analysis demonstrates that this result cannot be accounted for by single-stage decision-making algorithms which combine all the evidence pertaining to a decision into a common metric. This shows that human decision making is not information-optimal and suggests that the generalization of current models of simple perceptual decision making to more complex decisions is not straightforward.     

Validity of Resumé Reviewers' Inferences Concerning Applicant Personality Based on Resumé Evaluation

Recruiters infer personal traits from job applicants' resumés and use these inferences in evaluating job applicants' employability. No research to date, however, has determined if resumé reviewers' inferences of applicants' personality drawn solely from resumé biographical data are valid. In the present study, resumé reviewers (N=52) examined one of two applicant resumés and then described the applicant's personality based on the Big 5 taxonomy. Validities of reviewers' inferences concerning applicant personality were assessed by correlating resumé reviewers' judgments with applicants' self‐reported Big 5 personality scores. Results suggested that valid personality inferences are possible based solely on resumé evaluation. We also found evidence suggesting that attending a brief training session may enhance reviewers' accuracy when inferring applicants' personality from resumé information.     

Consequences of brain tumour resection on emotion recognition

Emotion processing impairments are common in patients undergoing brain surgery for fronto-temporal tumour resection, with potential consequences on social interactions. However, evidence is controversial concerning side and site of lesions causing such deficits. This study investigates visual and auditory emotion recognition in brain tumour patients with the aim of clarifying which lesion sites are related to impairments in emotion processing from different modalities. Thirty-four patients were evaluated, before and after surgery, on facial expression and emotional prosody recognition; voxel-based lesion–symptom mapping (VLSM) analyses were performed on patients’ post-surgery MRI images. Results showed that patients’ performance decreased after surgery in both visual and auditory modalities, but, in general, recovered 3 months after surgery. In facial expression recognition, left brain-damaged patients showed greater post-surgery deterioration than right brain-damaged ones, whose performance specifically decreased for sadness and fear. VLSM analysis revealed two segregated areas in the left hemisphere accounting for post-surgery scores for happy (fronto-temporo-insular region) and surprised (middle frontal gyrus and inferior fronto-occipital fasciculus) facial expressions. Our findings demonstrate that surgical removal of tumours in the fronto-temporal region produces impairment in facial emotion recognition with an overall recovery at 3 months, suggesting a partially different representation of positive and negative emotions in the left and right hemispheres for visually – but not auditory – presented emotions; moreover, we show that deficits in specific expression recognition are associated with discrete lesion locations.     

Acquiescent responding in partially balanced multidimensional scales

We propose a method for controlling acquiescent response in which acquiescence response variance is isolated in an independent factor. This kind of procedure is available for perfectly balanced scales (i.e. half of the items are worded in the opposite direction to the other half with respect to a general trait). However, few questionnaires are designed so that exactly half of the items are worded in this way. If this is not the case, the available methods are useless. We propose to adapt the rotation method of Lorenzo‐Seva and Rodríguez‐Fornells to handle partially balanced scales (i.e. only a few items in the scale are worded in the opposite direction). The most important characteristic of our method is that it removes the variance due to acquiescent response from all the items in the questionnaire (i.e. the balanced subset of items, but also the unbalanced subsets of items). The usefulness of the method is illustrated in a numerical example.