Not just standing there: the use of postural coordination to aid visual tasks

Postural control is an integral part of all physical behavior. Recent research has indicated that postural control functions in a manner that facilitates other higher order (suprapostural) tasks. These studies, while showing that postural sway is modulated in a task specific manner, have not examined the form of postural coordination that allows for the achievement of these higher behavioral goals. The current study examined the relation between visual task constraints (viewing distance), environmental constraints (changes in the surface of support), and the postural coordination employed to complete the task. Thirty-one participants were asked to perform a reading task while standing on various surfaces. Postural motion was recorded from the head, cervico-thoracic spine, sacrum (hip), and ankle. It was found that body segment coordination changed as a function of surface characteristics and task constraints. Additionally, the overall pattern of postural sway (head motion) replicated that which was found by Stoffregen et al. [J. Exp. Psychol. Human Percep. Perform. 25 (6) (1999) 1641]. These findings suggest that postural adaptation involves more than basic reduction or increase of motion; it involves the functional coordination of body segments to achieve a particular goal. The data further suggest that there is a need to examine postural control in the absence of external perturbations.     

Learning a pointing task with a kinematically redundant limb: Emerging synergies and patterns of final position variability

The study tested a hypothesis that practice of arm pointing movement can lead to a reorganization of the joint coordination reflected in the emergence of several synergies based on the same set of joints. In particular, involvement of the wrist may represent a choice by the central nervous system and not be driven by the typical “freezing-to-freeing” sequence. The effects of practice on the kinematic patterns and variability of a “fast and accurate” pointing movement using a pointer were studied. An obstacle was placed between the initial position and the target to encourage a curvilinear trajectory and larger wrist involvement. Practice led to a decrease in variability indices accompanied by an increase in movement speed of the endpoint and of the elbow and the shoulder, but not of the wrist joint. Five out of six subjects decreased the peak-to-peak amplitude of wrist motion. Before practice, the variability along the line connecting the endpoint to the shoulder (extent) was similar to that in the direction orthogonal to this line. After practice, variability was reduced along the extent, but not along the orthogonal direction perpendicular to this line. Prior to practice, indices of variability of the endpoint were lower than those of the marker placed over the wrist; after practice, the endpoint showed higher variability indices than the wrist. We interpret the data as consequences of the emergence of two synergies: (a) Pointing with a non-redundant set of the elbow and shoulder joints; and (b) keeping wrist position constant. The former synergy is based on a structural unit involving the elbow and the shoulder, while the latter is based on a structural unit that includes all the major arm joints.     

The Dynamics of Families in Business: How Therapists can Help in Ways Consultants Don't

Family-owned businesses comprise 80–90% of companies in the United States of America and employ almost one-half of the US work force. Only 70% of these companies will make the transition into the family's second generation of leadership, however, sometimes partly because families work differently and toward different goals than do businesses. Interpersonal family dynamics—spousal, parental, father-son, father-daughter, sibling and in-law—can be a major factor in the failure to thrive. Exploring family systems theory, this article explains why these troubled families in business together need therapeutic practitioners' unique experience—experience consultants usually do not possess.     

任务难度对基于位置返回抑制时间进程的影响

在返回抑制的实验范式下,采用线索一靶子模式进行了视觉字母觉察实验、实验发现,返回抑制在线索与靶子之间的时间间隔（ＳＯＡ）为７００ｍｓ时出现,且在９００ｍｓ时消退。这与先前许多实验发现的返回抑制在ＳＯＡ为３００ｍｓ左右时出现的结果不一致。作者认为,实验任务的难度是影响返回抑制时间进程的一个重要因素。     

Nonlinearity in the Epidemiology of Complex Health and Disease Processes

Theoretical Medicine and Bioethics - The challenges posed by chronic illness have pointed out to epidemiologists the multifactorial complex nature of disease causality. This notion has been...     

The crying boss: Activating “human resources” through sensitivity training in 1970s Sweden

This article examines the introduction of “sensitivity training” to 1970s Swedish work life. Drawing upon a range of empirical materials, I explore the politics that were involved in the process of translating and adapting this group dynamic method to the Swedish context and consider how its proponents argued for its value. By approaching sensitivity training as an attempt to govern, shape, and regulate both human beings and the work organizations of which they were a part, I argue that sensitivity training presents an unexpectedly early example of a governing rationality that has elsewhere been described and theorized as “neoliberal.” The fact that sensitivity training was established in Swedish work life already in the early 1970s thus challenges the historiography of neoliberal modes of government, which have elsewhere been associated with a neoliberal shift in state policies occurring in the 1980s and 1990s. The article demonstrates how emotionally liberating practices in the late 1960s and early 1970s were embraced by some of the most politically influential actors in contemporary Swedish society, such as the corporate sector and the trade unions. As blue-collar trade unions and social democrats voiced increasingly far-reaching demands concerning workplace democracy and improved workplace conditions, advocates of sensitivity training presented their method as crucial to the process of “democratizing” and “humanizing” Swedish work life. Intimately associated with the new therapies of humanistic psychology, sensitivity training was used within the corporate sector to foster a more emotional and authentic leadership style that would embrace the values of emotional awareness, self-expression, and self-actualization. The crying boss emerged in this context as a key figure in the project of creating a “democratic” and psychologically satisfying organization. Yet, sensitivity training was also described as a means for companies to make better use of what was now asserted as their most important economic asset: the human being. From the outset, the idealistic vision of an emotionally liberated, democratic workplace was thus entangled with a specific kind of economic rationality, in which the emotionally liberated, self-actualizing individual emerged as a capital or asset that would be better utilized if the organization allowed—even encouraged—employees to engage in their own well-being and self-optimization.     

The assistant referees’ activity in refereeing elite football: Preoccupations when not judging offside

ObjectiveThe purpose of this research was to study the preoccupations assistant referees had to participate in decision making about duels during football games.DesignResearch adopted a phenomenological framework to investigate the assistant referees’ lived experiences in order to understand their activity when they judged duels in match.MethodThis study investigated six professional football matches. Researchers conducted a participatory observation of the refereeing team before each match. Twelve self-confrontation interviews with each assistant referee of each match were conducted in order to make him/her describing his/her unfolding lived experience during the match.ResultsIn case of players’ duels, the perception of contextual cues enabled the assistants to appraise the occurring of a decision process with the central referee. For the assistants, the occurring of a decision process with the central referee meant his priority to intervene in the adjudication of duels, while the absence of decision process with the central referee meant for the assistants the possibility to intervene. The assistants adjusted their way of judging duels to how the central referee judged the previous ones.ConclusionsThe participation of assistants in decision making about duels depends on their preoccupations concerning the central referee’s priority. The way assistants perceive the central referee’s contextual judgment shapes the way they adjudicate duels. A latent intention to coordinate with the central referee, in relation with their collaborative tasks, is embedded in their preoccupations. Our results are a platform to develop further research about the referees’ collective activity.     

Effect of Stroke on Joint Control during Reach-to-Grasp: A Preliminary Study

Abstract

We investigated changes in control of inter-segmental dynamics underlying upper extremity dyscoordination caused by stroke. Individuals with stroke and healthy individuals performed a natural reach-to-grasp movement. Kinetic analysis revealed that both groups rotated the shoulder by muscle torque and used interaction torque to rotate the elbow. However, individuals with stroke used interaction torque less than healthy individuals, actively suppressing a substantial portion of it. This resulted in inefficient use of active control and dyscoordination of the upper extremity. The degree of interaction torque suppression and inefficiency of active control at the elbow positively correlated with stroke severity. The increased interaction torque suppression can be a strategy used by individuals with stroke to compensate for deficient feedforward control of this torque.     

All Behavior is choice: Revisiting an evolutionary theory's account of behavior on single schedules

The axiomatic principle that all behavior is choice was incorporated into a revised implementation of an evolutionary theory's account of behavior on single schedules. According to this implementation, target responding occurs in the context of background responding and reinforcement. In Phase 1 of the research, the target responding of artificial organisms (AOs) animated by the revised theory was found to be well described by an exponentiated hyperbola, the parameters of which varied as a function of the background reinforcement rate. In Phase 2, the effect of reinforcer magnitude on the target behavior of the AOs was studied. As in Phase 1, the AOs' behavior was well described by an exponentiated hyperbola, the parameters of which varied with both the target reinforcer magnitude and the background reinforcement rate. Evidence from experiments with live organisms was found to be consistent with the Phase-1 predictions of the revised theory. The Phase-2 predictions have not been tested. The revised implementation of the theory can be used to study the effects of superimposing punishment on single-schedule responding, and it may lead to the discovery of a function that relates response rate to both the rate and magnitude of reinforcement on single schedules.     

To be at the tail of the lions or the head of the foxes?

Agents seeking an opportunity for profit often have to compete with others who pursue the same opportunity. When having to choose between a number of opportunities differing in their value and if individuals differ in their chances of outperforming others, the choice can be cognitively and emotionally demanding. We explore choice between opportunities using stylized Lions–Foxes games. In such a game, each of three players, with different odds of beating others, has to choose one of two contests that offer different rewards. After game theoretically analyzing the games, which we have experimentally employed, we report four experiments that vary in choice elicitation (repeated play or strategy method), in players' matching (random strangers or partners) and in rewards. Regarding contest choices, we found the choice of the higher value (and seemingly more prestigious) contest to be positively related to winning odds, contrary to what four out of the five (mixed, partially mixed, or pure) equilibria predict. Participants started out rather optimistic, with a large majority choosing the higher value option, but with experience, they approached the only viable of two pure strategy equilibria. Still, mixing continued via reacting to past play and outcome, apparently balancing dissatisfaction from choosing either contest.