Deceleration requirements and the control of pointing movements

When a limb is moved from one position to a target object, the limb and the target frequently collide. Often, the goal of the movement is to strike the target with a particular magnitude of impact. For single-aiming movements, impact forces have been shown to increase systematically with both an increased movement amplitude and a decreased movement time, thus providing deceleration to the moving limb. Models of speed-accuracy trade-off, however, have neglected to account for the contribution of these impact forces in the control of accurate movements. The aim of this experiment was to examine the modifications in the control strategy as a function of the amount of impact force a subject is allowed to use in decelerating his or her limb. Results showed that the structure of the acceleration-time functions was dictated by the amount of impact force subjects were allowed to use in decelerating the limb. Movement endpoint variability decreased as more impact force was used. The experiment suggests that the impact with a target is an important contributor to the deceleration of the moving limb and a critical determinant of movement organization.     

Dynamical substructure of coordinated rhythmic movements.

A coordinated rhythmic movement pattern is a dynamical activity involving many hidden layers of rhythmic subtasks. To investigate this dynamical substructure, spectroscopic concepts and methods were applied to an interlimb rhythmic movement task requiring 1:1 frequency locking of two hand-held pendulums in 180 degrees phase relation. The pendulums could be of identical or very different dimensions, thereby providing different values of the ratio omega of uncoupled frequencies. Analyses focused on the power spectrum of continuous relative phase as a function of variation in omega. Predictions were derived from the theories of mode locking and fractal time. Experimental results were in agreement with theoretical expectations and were discussed in terms of the possible recruiting of rhythmic subtasks in the assembling of interlimb absolute coordination, the interdependence of these subtasks, and the general dynamical principles that relate coordinative processes occurring at different length and time scales.     

A meta-analytic comparison of the effectiveness of smoking cessation methods.

Meta-analysis was used to cumulate the results from 633 studies of smoking cessation, involving 71,806 subjects, that reported the proportion of successful quits. Self-care methods do not appear to be as effective as formal intervention methods. Instructional programs involving physicians were not more effective than other instructional programs. Conditioning-based techniques such as aversive methods had success rates similar to those of instructional methods, and among the instructional methods, those incorporating social norms and values were more successful than those relying solely on didactic approaches. Cumulation of quit rates from all available control groups indicated that, on average, 6.4% of the smokers could be expected to quit smoking without any intervention. This figure must be subtracted from the raw success rate to obtain the net success rate for each program. Directions for future research are discussed.     

Progress of research in the diagnosis of multiple sclerosis by study of the cerebrospinal fluid

There are neither specific cell investigations nor immunological tests for the diagnosis of MS. Various immunological alterations occur in the course of the disease, but none is unique to MS. Accurate diagnosis remains confined to the clinical field. The diagnosis can be supported by CSF analysis. Laboratory examinations can help to determine the particular stage of the disease and provide clues to the etiology and pathogenesis. The appearance of abnormal CSF levels increases the certainty of the diagnosis.     

The effect of the Müller-Lyer illusion on map reading.

One important reason for studying visual illusions is that they can influence real-world perception as people interact with human-made displays. Three experiments examined how the Müller-Lyer illusion affects distance judgments and decision-making in the complex graphical context of a map by having subjects estimate the lengths of road segment lines framed by inward-going or outward-going wings in actual maps, in control displays that had the map context removed, and in simulated maps. The experiments showed that (1) outward-going wings led to higher distance estimates than did inward-going wings to the same extent both with and without the map context, (2) decisions based on distances determined from maps were affected by Müller-Lyer elements in the maps, and (3) map readers' measurement behavior influenced the effect of the Müller-Lyer elements in maps. The discussion focuses on how certain display manipulations and task manipulations affect the Müller-Lyer illusion. In addition, the discussion addresses the instances in which using a map might be affected by misestimation due to Müller-Lyer elements.     

Development of procedures for rating posed emotional expressions across facial, prosodic, and lexical channels.

A number of rating systems are available to evaluate emotional communication in a single modality. The main purpose of this study was to develop procedures to train human raters to evaluate posed expressions of emotion across three different channels of communication, i.e., facial, prosodic/intonational, and lexical/verbal. These procedures were used to evaluate posed emotional expressions produced by individuals with unilateral brain lesions from stroke. Posers in this preliminary report were two right brain-damaged, two left brain-damaged, and two normal control right-handed adults who were matched on demographic and neurological factors. Eight emotional expressions, both positive and negative, were produced in three channels and rated for intensity, pleasantness, and category accuracy. 15 normal adults served as raters, five per channel. The rating procedures were comparable across channels, with analogous properties, and yielded substantial interrater agreement. In this small sample of posers, it was observed that the expressions of the right brain-damaged group were rated as the least accurate and those of the left brain-damaged group as the most intense. When patterns of individual performance across the channels were examined, performance was quiet consistent for the normal controls yet variable for the right brain-damaged persons. These observations are in keeping with the notion that patients with right hemisphere pathology have difficulty in emotional communication. In summary, these findings suggest that comparison of emotional expressions across multiple channels is feasible.     

Disgust sensitivity, trait anxiety and anxiety disorders symptoms in normal children.

There is evidence to suggest that disgust sensitivity plays a role in the development of small animal fears and phobias. Recently, Phillips, Senior, Fahy, and David (1998) [Phillips, M. L., Senior, C., Fahy, T., & David, A. S. (1998). Disgust: the forgotten emotion of psychiatry. British Journal of Psychiatry, 172, 373-375.] suggested that disgust sensitivity is also involved in various other anxiety-based symptoms (e.g. obsessive-compulsive complaints, social phobia). The present study sought to test this suggestion in a large sample of normal school children (N = 189). Children completed a measure of disgust sensitivity, the trait anxiety version of the Spielberger State-Trait Anxiety Inventory for Children and the Screen for Child Anxiety Related Emotional Disorders, an instrument that measures DSM-defined anxiety disorders symptoms. Disgust sensitivity was indeed found to be correlated with a broad range of anxiety disorders symptoms. However, results also indicated that these correlations were predominantly carried by trait anxiety. That is, when controlling for levels of trait anxiety, only specific phobia symptoms (including animal phobia, blood-injection-injury phobia and situational-environmental phobia) and separation anxiety disorder symptoms were significantly related to disgust sensitivity, although correlations were rather modest. Taken together, these findings cast doubts on the claim that disgust sensitivity is an unique and independent factor that contributes to a broad range of anxiety disorders.     

Dynamics of oralrespiratory coordination in full-term and preterm infants: I. Comparisons at 38-40 weeks postconceptional age

This study compares the coordination of pacifier sucking and breathing between healthy full-term, low risk preterm, and high risk preterm infants at 38–40 weeks postconceptional age. High and low risk preterm infants did not differ in overall score on a neurobehavioral examination (NAPI), but infants in the high risk group differed from the others in breathing frequency and in the coordination of breathing and sucking rhythms. For infants in the high risk group, sucking had less influence on respiratory frequency and patterns of coordination between the frequencies of sucking and breathing were simpler. Oral–respiratory coordination may be a useful marker of infants at risk for later speech problems.     

Randomized controlled trial of a brief problem-orientation intervention for suicidal ideation

Empirical evaluations suggest that problem orientation, the initial reaction to problems, differentiates suicidal youth from nonchnical controls and nonideating psychiatric controls. One promising area for intervention with suicidal youth relates to enhancing this specific coping skill. Nonclinical participants (N = 110) with active suicidal ideation were randomly assigned to receive a brief problem-orientation intervention or a control procedure. The current study evaluated the benefits of a brief prevention intervention based on the Problem-Solving Therapy model. Exposure to a brief video intervention regarding problem solving and coping skills was sufficient to elicit significant decreases in suicidal ideation and depression, but the intervention did not elicit improvements in problem orientation or other problem-solving abilities. These findings provide preliminary support for a brief, video-based problem-solving and coping skills module. However, considerable work in developing secondary prevention interventions remains.