Role Development

SUMMARY

In this chapter, I first explain my research stance, which reflects how I became interested in this study, as well as the personal perspective and professional background that I bring to the study, which may clarify how I may hear and listen to the participants and face biases that emerge (Ely et al., 1997; Tedlock, 1995; Van Manen, 1990). Next, I describe the research setting, the participants, and the methods for recruiting the participants. Finally, I outline the research procedures, data collection, data management, analysis, methods to achieve trustworthiness, presentation of the findings, negative analysis, and preparatory study.     

Sensori-motor integration during stance: Time adaptation of control mechanisms on adding or removing vision

Sudden addition or removal of visual information can be particularly critical to balance control. The promptness of adaptation of stance control mechanisms is quantified by the latency at which body oscillation and postural muscle activity vary after a shift in visual condition. In the present study, volunteers stood on a force platform with feet parallel or in tandem. Shifts in visual condition were produced by electronic spectacles. Ground reaction force (center of foot pressure, CoP) and EMG of leg postural muscles were acquired, and latency of CoP and EMG changes estimated by t-tests on the averaged traces. Time-to-reach steady-state was estimated by means of an exponential model. On allowing or occluding vision, decrements and increments in CoP position and oscillation occurred within about 2 s. These were preceded by changes in muscle activity, regardless of visual-shift direction, foot position or front or rear leg in tandem. These time intervals were longer than simple reaction-time responses. The time course of recovery to steady-state was about 3 s, shorter for oscillation than position. The capacity of modifying balance control at very short intervals both during quiet standing and under more critical balance conditions speaks in favor of a necessary coupling between vision, postural reference, and postural muscle activity, and of the swiftness of this sensory reweighing process.     

Re‐acquisition of upright vision while wearing visually left–right reversing goggles1

Abstract: The present research aimed to identify the important factor that makes it difficult to re‐acquire upright vision when wearing visually transposed goggles. The author wore left‐right reversing goggles and up‐down reversing goggles each for 14 days in 1986 and in 1990, respectively. When lying on one side with the left‐right reversing goggles on, the observer could get upside‐down vision, which made it possible to compare the difficulty of attaining upright vision when wearing up‐down reversing goggles. The only difference between the two situations is the dimension of the body image to be exchanged: The observer had to exchange the left and right halves of his body in the former situation and had to exchange along the top‐bottom axis of body in the latter situation. Introspective data revealed that attaining an upright sense is easier in the former situation; this means that the asymmetrical structure of our body in the top‐bottom dimension is an important factor in the difficulty of re‐acquiring upright vision.     

Well‐Being Blindness

Why are we still studying well‐being? We have a vested interest in understanding the good life, and the relevant data seem to be accessible to us all. The challenge is to explain why well‐being is one lasting philosophical topic among others in spite of our special epistemic relationship to it. This article argues that human nature renders us well‐being blind. On one side this is due to the heterogeneous nature of our interests. Some are directly mediated by conscious thought, others are not. Some are individualistically realized, others relationally. On the other side we suffer from cognitive biases that lead us to undervalue, indeed, to miss entirely, the important aspects of human life that do not depend on conscious attention. Consequently, there is reason to think that we shall never be satisfied with a theory of well‐being.     

Dynamics of postural control during bilateral stance – Effect of support area,visual input and age

The present study investigated the effect of support area, visual input and aging of the dynamics of postural control during bilateral stance. Fifteen young (22.1 ± 1.7 years) and fifteen older (68.3 ± 2.7 years) individuals completed four different 90 s bilateral stance trials: 1) shoulder wide feet distance with eyes open, 2) shoulder wide feet distance with eyes closed, 3) narrow feet distance with eyes open, and 4) narrow feet distance with eyes closed on a force plate form. The anterior (AP) and mediolateral (ML) center of pressure (COP) trajectories were calculated from the middle 60 s of the ground reaction forces and moments. Sample entropy (SaEn), correlation dimension (CoD), the largest Lyapunov exponent (LyE) and entropic half-life (ENT½) were calculated for the COP in both directions. In young individuals, a narrower support area resulted in a restricted movement solution space with lower SaEn, lower LyE and longer ENT½ in the executed motor control strategy, whereas it increased the CoD in the older individuals. During the eyes closed trials, SaEn, CoD and LyE increased and decreased ENT½ for both groups in the AP direction and increased SaEn and LyE in the ML direction for the older individuals alone. This indicates that aging is associated with direction- and task-dependent changes in the dynamics of the executed COP movements during postural stance tasks.     

A developmental dissociation between category and function judgments about novel artifacts

Two studies investigated the relative importance of information about intended design and current use on judgments about the function (Experiment 1) or category (Experiment 2) of novel artifacts in preschool children and adults. Adults assigned function and name on the basis of information about design across all conditions, while children’s decisions about function dissociated from decisions about category. Function judgments (in both 4 and 6-year-olds) were neutral between design and current use, both when the current use was idiosyncratic (e.g. performed by just one agent) and conventional (performed by many people; Experiment 1). By contrast, where category judgments were required for the very same objects (Experiment 2), children named according to design intentions - but only if the alternate function was idiosyncratic. Judging function and assigning category are thus cognitive tasks that draw on different information across development, a fact that should be captured by theories of developing artifact concept structure.     

Asymmetrical stabilization and mobilization exploited during static single leg stance and goal directed kicking

The motor control properties of the right and left legs are dependent on the stabilization and mobilization features of the motor tasks. The current investigation examined the right and left leg control differences – interlateral asymmetries – during static single leg stance and dynamic goal directed kicking with an emphasis of the asymmetrical stabilization and mobilization components of movements. Ten young, healthy, right-leg preferred individuals with minimal kicking experience completed both tests on each limb. During static single leg stance, participants were requested to stand as still as possible with one leg in contact with a force platform. Interlateral asymmetries of the standing leg were quantified using postural variability measures of the center of pressure (COP) standard deviation in the anterior-posterior (SD-COP_AP) and medial-lateral (SD-COP_ML) directions, resultant COP length and velocity, and 95% COP elliptical area. During dynamic goal directed kicking, participants stood on two adjacent force platforms in a side-by-side foot position and kicked a soccer ball toward three different directions as soon as they received an auditory cue of kicking. Three targets were located −30°, 0° or 30° in front and 3.05 m away from the participants’ midline. Participants kicked the ball toward the targets with each of their feet. The vertical ground reaction force (vGRF) of the kicking leg was used to define the preparation (from above two standard deviations of vGRF baseline to toe-off) and swing (from toe-off to toe-return) phases of dynamic kicking. To determine the presence of interlateral asymmetries during dynamic kicking, the magnitude and timing of the anticipatory postural adjustments (APA) during the preparation phase of kicking were quantified using the lateral net COP (COPnet-ML) time series derived from both force platforms. Postural variability measures of the support leg and the kinematic joint range of motion (JROM) trajectories of the kicking leg were also used to examined interlateral asymmetries. During static stance, no between-leg significance was identified for all dependent measures of COP variability suggesting symmetrical stabilization. During the preparation phase of kicking, both right and left leg kicking exhibited a similar level of APA magnitude, although the left leg kicking was shown to reach its maximum APA magnitude earlier than the right leg. In the support leg role, the right leg showed greater COP variability in the ML direction as compared to the left support leg and greater COP variability was observed when kicking in the ipsilateral direction compared to the center and contralateral directions. For mobilization control, the left kicking leg showed greater JROM displacements at the distal (knee and ankle) joints and reduced JROM primarily with hip frontal plane movements compared to the right kicking leg. The reported interlateral asymmetries during kicking may reflect a behavioral adaptation that results in differential stabilization between the right and left legs. Overall, the findings suggest that novel tasks, such as dynamic goal directed kicking, appear to be more sensitive than static balance in identifying interlateral asymmetries.     

Undisturbed Upright Stance Control in the Elderly: Part 1. Age-Related Changes in Undisturbed Upright Stance Control

The authors investigated age-related changes in postural control in 33 healthy young adults (18-31 years), 29 seniors (62-75 years), and 22 elderly people (75-96 years). A force platform recorded the results. The horizontal motions of the center of gravity (CG_h) and their difference in the plane of support CP - CG_v were deduced from the complex center of pressure (CP) trajectories. With fractional Brownian modeling, one can establish that the aging process seems to induce a transition phase in which seniors take more time to initiate the corrective process in the mediolateral (ML) axis than do younger people. The elderly develop a new strategy characterized by the mobilization of higher neuromuscular energy to maintain equilibrium. In the ML axis, the larger displacements could be caused mainly by a hip strategy that could facilitate step initiation. In the anteroposterior (AP) axis, seniors and elderly individuals maintain a relative ability to stabilize their CG into the base of support compared with younger people.     

The relation between preparatory stance and trunk rotation movements

The influence of preparatory stance on rotation movement reaction time of the trunk by bending of the knee and hip joint(s) was examined in 12 subjects. Four preparatory stances were examined: straight knee and hip extension (STAND), slight flexion of knee joints and hip joint (LIGHT), deep flexion (DEEP), and free initial position, i.e. that felt to be the most comfortable and effective (FREE). There was no significant influence of the preparatory stance on hip latency, but there were significant differences between the preparatory stances on response time (RT) and movement time (MT). Furthermore, using a quadratic curve fitting technique, knee joint angles of 24.8 degrees and a hip joint angle of 23.3 degrees were shown to be the optimum flexion angles in the preparatory stance for the initiation of quick trunk rotation movements. It is proposed that mechanical factors have considerably more effects on trunk rotation movements than does the nervous system.     

Language, moral order and political praxis

The paper argues that the debate between objectivist criticism and postmodern critique represents a fracturing of the modes of mundane social and linguistic practice. The two together miss the open-textured character of language-in-use and the reflexive properties of situated human practice. Both difference and agreement are grounded in the multiplicity of criteria that are a feature of the logical grammar of language, and therefore of everyday praxis, including that of critique. To escape the duality of foundationalism on the one hand, and radical relativism on the other, attention to the praxiological details of human action and reasoning is needed. The paper draws on Wittgensteinian philosophy and ethnomethodological studies of reasoning to make its case.