Motor Programming as a Function of Constraints on Movement Initiation

Three experiments are reported that test the hypothesis that under certain conditions programming time is a function of the directional accuracy demand of a response, directional accuracy being quantified by the minimal angle subtended at the point of movement initiation by the circular targets within the response. Subjects in three simple reaction time experiments were required to tap a single target or a series of circular targets as rapidly as possible with a hand-held stylus. Experiments 1 and 3 showed that the subtended angle (SA) of a response can have a more powerful effect on programming time, as indexed by reaction time and premotor time, than the number of movement parts in the response. The results of Experiment 2 revealed that the locus of the directional accuracy effect was SA and not target size or movement distance. In all three experiments, response SA was a better predictor of programming time than was number of movement parts, target size, movement distance, movement time, and average movement velocity. The findings support the notion that constraints placed upon movement initiation by the directional accuracy demand of the task can play an important role in determining the length of the programming process.     

The Effect of Interpolated Motor Activities in Short-Term Motor Memory

This experiment examined the effect of an interpolated motor response on short-term retention of a blind positioning movement. The interpolated response was varied in degree of similarity to the response length (± 25, ± 50, and ± 100 mm.), in number of repetitions (0, 1, or 5), and in temporal position (immediate or delayed), with a retention interval of 25 sec. Absolute error was not affected but a systematic change in response bias due to interpolated motor activity was found. When an interpolated response was longer than the response length, the tendency to undershoot decreased. The defay of the interpolated response was relatively more important than the number of repetitions in producing a positive shift in response bias. These results are interpreted as evidence for a form of interference in short-term motor memory.     

On the Role of Visual Afferent Information for the Control of Aiming Movements Toward Targets of Different Sizes

The authors investigated (a) whether the specificity of practice hypothesis is mediated by the importance of visual afferent information for the control of manual aiming movements and (b) how movement planning and online correction processes to the movement initial impulse are affected by the withdrawal of visual information in transfer. In acquisition, participants (N = 40) aimed at targets of different sizes in a full-vision or in a target-only condition before being transferred to a target-only condition without knowledge of results. The results supported the hypothesis that learning is specific to the source or sources of afferent information that are more likely to ensure optimal performance. The results also suggested that individuals will not always use visual afferent information more extensively when aiming at a small rather than at a large target. Instead, in a temporally constrained task, the relative efficiency of visually based corrections appears to mediate how exclusively an individual will rely on online visual afferent information for movement control. Finally, the detailed kinematic analysis performed in the present study clearly indicated that online modifications to the movement primary impulse are possible, arguing for a continuous or pseudo-continuous control of relatively slow aiming movements on the basis of visual afferent input.     

Effects of Training on Endurance in Hanging by The Hands

The effect of training on endurance in hanging by the hands from a horizontal bar was examined by timing the duration of such hanging in six male and five female subjects each weekday for 2 weeks. A significant increase in endurance was observed. The results, both subjective and objective, indicated the most important factors in the training to be increased psychological endurance of discomfort and increased muscular strength and efficiency.     

Spontaneously Hypertensive Rats: Possible Animal Model of Sleep-Related Movement Disorders

Clinical experience suggests that restless legs syndrome (RLS), periodic leg movement (PLM), and attention-deficit hyperactivity disorder (ADHD) may co-occur in both children and adults. The purpose of the present study was to provide an electrocorticography and electromyography evaluation of the spontaneously hypertensive rat (SHR) to investigate the potential of this rat strain as an animal model of RLS–PLM. Initial work focused on evaluating sleep patterns and limb movements during sleep in SHR, having normotensive Wistar rats (NWR) as control, followed by comparison of two treatments (pharmacological–dopaminergic agonist treatment and nonpharmacological–chronic physical exercise), known to be clinically beneficial for sleep-related movement disorders. The captured data strengthen the association between SHR and RLS–PLM, revealing a significant reduction on sleep efficiency and slow wave sleep and an increase on wakefulness and limb movements for the SHR group during the dark period, as compared to the NWR group, effects that have characteristics that are strikingly consistent with RLS–PLM. The pharmacological and nonpharmacological manipulations validated these results. The present findings suggest that the SHR may be a useful putative animal model to study sleep-related movement disorders mechanisms.     

The Effect of Load on Torques in Point-to-Point Arm Movements: A 3D Model

A dynamic, 3-dimensional model was developed to simulate slightly restricted (pronation-supination was not allowed) point-to-point movements of the upper limb under different external loads, which were modeled using 3 objects of distinct masses held in the hand. The model considered structural and biomechanical properties of the arm and measured coordinates of joint positions. The model predicted muscle torques generated by muscles and needed to produce the measured rotations in the shoulder and elbow joints. The effect of different object masses on torque profiles, magnitudes, and directions were studied. Correlation analysis has shown that torque profiles in the shoulder and elbow joints are load invariant. The shape of the torque magnitude-time curve is load invariant but it is scaled with the mass of the load. Objects with larger masses are associated with a lower deflection of the elbow torque with respect to the sagittal plane. Torque direction–time curve is load invariant scaled with the mass of the load. The authors propose that the load invariance of the torque magnitude–time curve and torque direction–time curve holds for object transporting arm movements not restricted to a plane.     

Index to Volume 129

This study addresses the basic structure of playfulness in adults from a psy-cho-lexical approach and its relationship with the sense of humor. Using items derived from a corpus analysis of written accounts in the German language, five factors were derived (N = 195); that is, (a) cheerful-engaged; (b) whimsical; (c) creative-loving; (d) intellectual; and (e) impulsive. Their contents strongly overlap in comparison with an earlier study using this approach. However, the correlation of the intellectual component with two current measures of adult playfulness was low, and the impulsive component was not correlated with these measures. The question arises as to whether these aspects exist only as components in the implicit psychological and linguistic theories. The sense of humor was most strongly related with the cheerful-engaged factor while some “humor skills” were particularly related to other factors; for example, finding humor under stress with the intellectual component. This study helps toward a better understanding of the basic structure of playfulness in adults.     

The Analytical Theatre: Freud and Ibsen

The author describes how an illusion of timelessness was manifested in the psychoanalytic process with a four and a half year old boy. This illusion turned out to serve as a protection against overwhelming death-anxiety and an intolerable experience of separateness. Development in the direction of a perception of time as linear appeared to be connected to the relinquishment of a two-dimensional, adhesive mode of identification, simultaneously with the development of a conception of three-dimensionality. This change seemed to be brought about by the introjection of the holding and boundary-shaping skin-function of the analyst, which implied the conception of a closed space, a container, and the realization of an essential third instance. The psychoanalytical process made explicit the paramount importance which the symbolic presence of the paternal function in the mother has for her capacity for holding and containment and as the premise for the infant's perception of reality, including the development of the dimensions of time and space.     

Variable coordination of eye and head movements during the early development of attention: A longitudinal study of infants aged 12–36 months

This longitudinal study investigated the effects of attentional development on peripheral stimulus localization by analyzing the eye and head movements of toddlers as they matured from 12 to 36 months. On each trial of an experiment, a central fixation point and a 30° peripheral stimulus were presented, such that in the gap condition the fixation disappeared 300 ms before the peripheral stimulus, whereas in the no-overlap condition it disappeared simultaneously as the peripheral stimulus, and in the overlap condition the fixation remained present when the peripheral target occurred. Results showed that eye and head movement latencies were highly correlated in all conditions and ages. However, at 12 months, head movements were as fast as eye movements, whereas during the subsequent development, eye movements became increasingly faster than head movements. These findings are indicative of a transition between 12 and 36 months due either to a change in attentional control, or to changes in the size of the visual field in which only eye movements occur.     

Changing institutional incentives to foster sound scientific practices: One department

Replicable research and open science are of value to our field and to society at large, but most universities provide no incentives to adopt these practices. Instead, current incentive structures favor novel research, which has led to a situation in which few researchers take the time to do replications, share protocols, or share data. Obviously, several approaches to remedy this situation are possible. However, little progress can be made if becoming involved in such activities reduces a researcher’s chances of rank and status advancement and other rewards. I describe in this article the way my department has modified our incentive structure to tackle this problem, including how the changes influence my research as a developmental psychologist. Finally, I offer suggestions for faculty who wish to initiate similar changes in their institutions.