Development of rule-based eye-hand-decoupling in children and adolescents

In the present study, we characterize how the ability to decouple guiding visual information from a motor action emerges during childhood and adolescence. Sixty-two participants (age range 8–15 yrs.) completed two eye-hand coordination tasks. In a direct interaction task, vision and motor action were in alignment, and participants slid their finger along a vertical touch screen to move a cursor from a central target to one of four peripheral targets. In an eye-hand-decoupled task, eye and hand movements were made in different planes and cursor feedback was 180° reversed. We analyzed whether movement planning, timing and trajectory variables differed across age in both task conditions. There were no significant relationships between age and any movement planning, timing, or execution variables in the direct interaction task. In contrast, in the eye-hand-decoupled task, we found a relationship between age and several movement planning and timing variables. In adolescents (13–15 yrs.), movement planning and timing was significantly shorter than that of young children (8–10 yrs.). Eye-hand-decoupled maturation emerged mainly during late childhood (11–12 yrs.). Notably, we detected performance differences between young children and adolescents exclusively during the eye-hand decoupling task which required the integration of rule-based cognitive information into the motor action. Differences were not observed during the direct interaction task. Our results quantify an important milestone for eye-hand-decoupling development in late childhood, leading to improved rule-based motor performance in early adolescence. This eye-hand-decoupling development may be due to frontal lobe development linked to rule-based behavior and the strengthening of fronto-parietal networks.     

Exploring the Within-Person Coupling of Reading Vision and Cognition in the Elderly

ABSTRACT

This study examined the within-person relationship between reading vision and cognitive functioning. Analysis was conducted on 36 community-dwelling elderly (age range?=?60–87) who completed a reading vision task and three cognitive tests (i.e., Rey Auditory Verbal Learning Task (AVLT), Letter Series, and Number Comparison) twice a day over 60 consecutive days. Significant within-person variability was found for the reading vision measure. Additionally, a main effect was found for reading vision and performance on the AVLT and Number Comparison task; such that on occasions when reading vision was poor, cognitive performance suffered.     

Homo Hierarchicus and ecclesial order

Abstract

To argue that the concept of hierarchy is a profoundly theological concept is peculiarly difficult at the present time in which there is a general assumption that all hierarchies are hierarchies of power, intrinsically oppressive, and incompatible with human freedom. Consequently there is a deep-seated suspicion of the notion whenever it is invoked – not least in the context of church ‘order’. Such a suspicion would have been inexplicable to those writers from whom we gain our earliest knowledge of the Christian Church. Though we cannot, nor should we try to, recreate the conditions of earlier ages in which the concept was understood with a richness and depth that are lacking in our own age, it is vital to expose the contemporary misuse and degradation of the concept and see that, in the life of the Church, the concept of hierarchy is not intended to be an articulation of power, but an eschatological expression of order. The recognition of the inhuman abuse of the concept down the ages should not blind us to the truth that its purpose is to act sacramentally as a sign of the heavenly kingdom.     

Plane of Motion Mediates the Coalition of Constraints in Rhythmic Bimanual Coordination

The authors hypothesized that the modulation of coordinative stability and accuracy caused by the coalition of egocentric (neuromuscular) and allocentric (directional) constraints varies depending on the plane of motion in which coordination patterns are performed. Participants (N = 7) produced rhythmic bimanual movements of the hands in the sagittal plane (i.e., up-and-down oscillations resulting from flexion—extension of their wrists). The timing of activation of muscle groups, direction of movements, visual feedback, and across-trial movement frequency were manipulated. Results showed that both the egocentric and the allocentric constraints modulated pattern stability and accuracy. However, the allocentric constraint played a dominant role over the egocentric. The removal of vision only slightly destabilized movements, regardless of the effects of directional and (neuro)muscular constraints. The results of the present study hint at considering the plane in which coordination is performed as a mediator of the coalition of egocentric and allocentric constraints that modulates coordinative stability of rhythmic bimanual coordination.     

Exploring the Limits of Peripheral Vision for the Control of Movement

The role played by peripheral visual information in the control of aiming movements is not fully understood, as is indicated by the conflicting results reported in the literature. In the present study, the authors tested and confirmed the hypothesis that the source of the conflict lies in the portion of the visual peripheral field that has been under scrutiny in the different studies. Participants (N = 60) moved a computer mouse from a fixed starting position to 1 of 3 targets under varied vision conditions. The portion of the peripheral visual field that best ensured directional accuracy of a sweeping movement was found to be located between 20° and 10° of visual angle, whereas the area found to favor directional accuracy of an aiming movement comprised 30° through 10° of visual angle.     

Good and Bad Years: An Index of American Social,Economic, and Political Threat (1920–1986)

Information provided by 196 U.S. history professors, indicating the degree to which they considered each of the years from 1920 to 1986 threatening to the established order and way of life in America, was pooled to form a social, economic, and political threat (SEPT) index. Interrater reliability was high, and substantial test-retest reliability was evident for a selected subsample over a 6-month period. The index significantly correlated with 11 objective indices of threat, including the suicide rate, unemployment rate, rise and fall of common stocks, and number of military men on active duty. Several studies involving threat and authoritarianism were replicated and in some instances extended with the SEPT index (McCann & Stewin, 1984; Sales, 1972, 1973). The pseudo-archival SEPT index has utility when relatively global estimates of prevailing threat are required for historiometric research testing a diversity of hypotheses gleaned from psychological, sociological, historical, and political science theories.     

The functional role of central and peripheral vision in the control of posture

Three experiments were conducted to investigate the role of central and peripheral vision (CV and PV) in postural control. In Experiment 1, either the central or peripheral visual field were selectively stimulated using a circular random dot pattern that was either static or alternated at 5 Hz. Center of foot pressure (CoP) was used to examine postural sway during quiet standing under both CV and PV conditions. The results showed that, when the visual stimulus was presented in the periphery, the CoP area decreased and more so in the anterior-posterior (AP) than in the medio-lateral (ML) direction, indicating a characteristic directional specificity. There was no significant difference between the static and dynamic (alternating) conditions. Experiment 2 investigated the directional specificity of body sway found in Experiment 1 by having the trunk either be faced toward the stimulus display or perpendicularly to it, with the head always facing the display. The results showed that the stabilizing effect of peripheral vision was present in the direction of stimulus observation (i.e., the head/gaze direction), irrespective of trunk orientation. This suggested that head/gaze direction toward the stimulus presentation, rather than a biomechanical factor like greater mobility of the ankle joint in AP direction than in ML direction, was essential to postural stability. Experiment 3 further examined whether the stabilizing effect of peripheral vision found in Experiments 1 and 2 was caused because more dots (500) were presented as visual cues to the peripheral visual field than to the central visual field (20 dots) by presenting the same number of dots (20) in both conditions. It was found that, in spite of the equal number of dots, the postural sway amplitudes were larger for the central vision conditions than for the peripheral vision conditions. In conclusion, the present study showed that peripheral rather than central vision contributes to maintaining a stable standing posture, with postural sway being influenced more in the direction of stimulus observation, or head/gaze direction, than in the direction of trunk orientation, which suggests that peripheral vision operates primarily in a viewer-centered frame of reference characterized by the head/gaze direction rather than in a body-centered frame of reference characterized by the anatomical planes of the body.     

On the role of peripheral visual afferent information for the control of rapid video-aiming movements

It has been shown that, even for very fast and short duration movements, seeing one's hand in peripheral vision, or a cursor representing it on a video screen, resulted in a better direction accuracy of a manual aiming movement than when the task was performed while only the target was visible. However, it is still unclear whether this was caused by on-line or off-line processes. Through a novel series of analyses, the goal of the present study was to shed some light on this issue. We replicated previous results showing that the visual information concerning one's movement, which is available between 40 degrees and 25 degrees of visual angle, is not useful to ensure direction accuracy of video-aiming movements, whereas visual afferent information available between 40 degrees and 15 degrees of visual angle improved direction accuracy over a target-only condition. In addition, endpoint variability on the direction component of the task was scaled to direction variability observed at peak movement velocity. Similar observations were made in a second experiment when the position of the cursor was translated to the left or to the right as soon as it left the starting base. Further, the data showed no evidence of on-line correction to the direction dimension of the task for the translated trials. Taken together, the results of the two experiments strongly suggest that, for fast video-aiming movements, the information concerning one's movement that is available in peripheral vision is used off-line.     

Binocular depth perception in the pigeon.

By means of a discrete-trial simultaneous discrimination procedure, pigeons were trained to respond differentially to visual arrays that were identical except that one of them contained a circle displaced in depth when viewed stereoscopically. Performance was severely disrupted when one eye was occluded. The monocular deficit was peculiar to the depth task, inasmuch as no such decrement was seen on a pattern discrimination. The results imply that presence of the displaced circle was discriminated on the basis of a binocular cue. It was also found that pigeons could discriminate the direction of the displacement. Discrimination of depth was independent of the global form and still occurred when elements of the array were randomly displaced in depth. Performance was not disrupted when the absolute convergence angle of the depth stimulus was changed. The cue that consistently accounted for the behavior seen was the detection of the relative angles of convergence--that is, the retinal disparity of the two planes in depth. Thus, despite the lateral position of the eyes of the pigeon, a small binocular field mediates the binocular discrimination of near objects in depth.     

观察不同形状和颜色时眼运动的顺序性

实验使用EVM3200型眼动仪测量被试在观察四种不同形状和四种不同颜色时眼运动轨迹的特点,来研究人眼运动的顺序性。结果表明：人眼在观察不同形状和颜色时,眼运动具有时间序列和空间序列的特性;形状和颜色一样具有诱目性序列特征;眼运动凝视点受到刺激所处空间位置的明显影响;首次凝视点是研究眼运动的重要变量。