Perception of biological motion from limited-lifetime stimuli

The visual perception of human movement from sparse point-light walkers is often believed to rely on local motion analysis. We investigated the role of local motion in the perception of human walking, viewed from the side, in different tasks. The motion signal was manipulated by varying point lifetime. We found the task of coherence discrimination, commonly used in biological motion studies, to be inappropriate for testing the role of motion. A task requiring temporal information showed a strong performance drop when fewer points were used or when the image sequence was sampled and displayed at a reduced frame rate. Irrespective of the frame rate, performance did not vary with point lifetime. We concluded that local motion is not required for the perception of tested biological movements, suggesting that the analysis of biological motion does not benefit from examining local motion. The reliance of perception on the number of displayed points and frames supports the idea that biological motion is perceived from a sequence of spatiotemporally sampled forms.     

Overactive action monitoring in obsessive-compulsive disorder: evidence from functional magnetic resonance imaging

The anterior cingulate cortex (ACC) in patients with obsessive-compulsive disorder (OCD) has been found to be hyperactive at rest, during symptom provocation, and after commission of errors in cognitive tasks. This hyperactivity might reflect an abnormality in conflict detection, a hypothesized basic mechanism for the action-monitoring function of the ACC. This hypothesis was tested using functional magnetic resonance imaging, by scanning 11 OCD patients and 13 matched control subjects while they performed a version of the continuous-performance task with four trial types that induced graded levels of response conflict. Although a behavioral index of conflict (i.e., accuracy) was similar for patients and control subjects, the ACC activation was increased in patients during high-conflict trials. The error-related activity in the same brain region was also higher in patients, consistent with previous electrophysiological findings. Both conflict- and error-related activity showed trends for positive correlations with severity of OCD symptoms, but not with anxiety. These findings suggest that as part of an overactive action-monitoring system, the ACC is more directly involved in the pathophysiology of OCD than previously thought.     

Delineating generalized anxiety: A preliminary investigation

The present study examined the nature of generalized anxiety, which was defined as the constellation of symptoms listed as diagnostic criteria for generalized anxiety disorder in DSM-III-R. Generalized anxiety was assessed by means of a questionnaire that was especially constructed for this study. Although multidimensional scaling of symptoms reported by a clinically anxious sample produced orthogonal anxiety and panic dimensions, many symptoms were common to both dimensions. Whereas worry was found to be the cardinal feature of generalized anxiety, respiratory symptoms were found to associate closely with panic. These dimensions were replicated in a student sample. It is argued that while generalized anxiety symptoms constitute a unique dimension in the field of anxiety disorders, both panic and generalized anxiety may be linked with a basic anxiety response system. The findings also indicated that worry associated more closely with generalized anxiety than did apprehensive expectations. The heuristic value of the findings are discussed in light of the issue relating to an anxiety-panic continuum.     

Neuroscience and Whitehead I: Neuro-ecological Model of Brain

Neuroscience has made enormous progress in understanding the brain and its various neuro-sensory and neuro-cognitive functions. However, despite all progress, the model of the brain as well as its ontological characterization remain unclear. The aim in this first paper is the discussion of an empirically plausible model of the brain with the subsequent claim of a neuro-ecological model. Whitehead claimed that he inversed or reversed the Kantian notion of the subject by putting it back into the ecological context of the world, the so-called reformist subjectivist principle. Based on empirical evidence about the experience-dependence of the brain’s spontaneous activity, I argue for an analogous inversion or reversion with regard to the model of brain: empirical evidence is well compatible with a neuro-ecological model which extends beyond and integrates both Humean neuro-sensory and Kantian neuro-cognitive models. I conclude that a neuro-ecological and process-based model of brain and its relationship to the world may offer a novel model of brain that carries major ontological implications as they shall be discussed in the second paper.     

Mathematical logic: Tool and object lesson for science

The object lesson concerns the passage from the foundational aims for which various branches of modern logic were originally developed to the discovery of areas and problems for which logical methods are effective tools. The main point stressed here is that this passage did not consist of successive refinements, a gradual evolution by adaptation as it were, but required radical changes of direction, to be compared to evolution by migration. These conflicts are illustrated by reference to set theory, model theory, recursion theory, and proof theory. At the end there is a brief autobiographical note, including the touchy point to what extent the original aims of logical foundations are adequate for the broad question of the heroic tradition in the philosophy of mathematics concerned with the nature of the latter or, in modern jargon, with the architecture of mathematics and our intuitive resonances to it.     

Enhanced Hippocampal CA1 LTP but Normal Spatial Learning in Inositol 1,4,5-trisphosphate 3-kinase(A)-Deficient Mice

To define the physiological role of IP₃3-kinase(A) in vivo, we have generated a mouse strain with a null mutation of the IP₃3-kinase(A) locus by gene targeting. Homozygous mutant mice were fully viable, fertile, apparently normal, and did not show any morphological anomaly in brain sections. In the mutant brain, the IP₄ level was significantly decreased whereas the IP₃ level did not change, demonstrating a major role of IP₃3-kinase(A) in the generation of IP₄. Nevertheless, no significant difference was detected in the hippocampal neuronal cells of the wild-type and the mutant mice in the kinetics of Ca²⁺ regulation after glutamate stimulation. Electrophysiological analyses carried out in hippocampal slices showed that the mutation significantly enhanced the LTP in the hippocampal CA1 region, but had no effect on the LTP in dentate gyrus (DG). No difference was noted, however, between the mutant and the wild-type mice in the Morris water maze task. Our results indicate that IP₃3-kinase(A) may play an important role in the regulation of LTP in hippocampal CA1 region through the generation of IP₄, but the enhanced LTP in the hippocampal CA1 does not affect spatial learning and memory.     

Using bifactor models to identify faking on Big Five questionnaires

To identify faking, bifactor models were applied to Big Five personality data in three studies of laboratory and applicant samples using within‐subjects designs. The models were applied to homogenous data sets from separate honest, instructed faking, applicant conditions, and to simulated applicant data sets containing random individual responses from honest and faking conditions. Factor scores from the general factor in a bifactor model were found to be most highly related to response condition in both types of data sets. Domain factor scores from the faking conditions were found less affected by faking in measurement of Big Five domains than summated scale scores across studies. We conclude that bifactor models are efficacious in assessing the Big Five domains while controlling for faking.