Influence of Destabilization on the Temporal Characteristics of lquot;Volitionalrquot; Stepping

Previous work suggests that there may be fundamental differences between compensatory stepping responses evoked by postural perturbation and visually cued "volitional" stepping (e.g., gait initiation). In contrast to visual cueing, postural destabilization evokes an array of sensory inputs that are intrinsically linked to the mobilization of rapid compensatory responses. The hypothesis examined in this study was that this fundamental difference would lead to distinct changes in the temporal characteristics of the stepping response. Six healthy young adults were instructed to step quickly in response to either visual cueing or anterioposterior platform motion. Both forward and backward stepping responses were characterized, using measures of vertical ground reaction force. A stereotypical temporal patterning of the stepping response occurred in both stimulus conditions and both directions of stepping, and anticipatory postural adjustments were evident in all trials. However, postural destabilization led to a more rapid initiation and execution of the temporal pattern, in comparison with visually cued responses. The most pronounced effect was seen in the duration of the response, which was reduced by a factor of two, with approximately proportional foreshortening of both the preparatory and swing phases. The results suggest that sensory information conveying a state of instability has a distinct influence on the characteristics of a subsequent stepping reaction. The persistence of the anticipatory postural adjustments suggests that the failure to see this element of the response in previous studies may reflect fundamental differences between volitional and unplanned compensatory stepping.     

The Timing Effects of Accent Production in Periodic Finger-Tapping Sequences

When subjects are required to produce short sequences of equally paced finger taps and to accentuate one of the taps, the interval preceding the forceful tap is shortened and the one that immediately follows the accent is lengthened. Assuming that the tapping movements are triggered by an internal clock, one explanation attributes the rnistiming of the taps to central factors: The momentary rate of the clock is accelerated or decelerated as a function of motor preparation to, respectively, increase or decrease the movement force. This hypothesis predicts that the interresponse intervals measured between either tap movement onsets or movement terminations (taps) will show the same timing pattern. A second explanation for the observed interval effects is that the tapping movements are triggered by a regular internal clock but the timing of the successive taps is altered because the forceful movement is completed in less time than the other tap movements are. This "peripheral" hypothesis predicts regular timing of movement onsets but distorted timing of movement terminations. In the present study, the trajectories of the movements performed by subjects were recorded and the interresponse intervals were measured at the beginning and the end of the tapping movements. The results of Experiment 1 showed that neither model can fully explain the interval effects: The fast forceful movements were initiated with an additional delay that took into account the small execution time of these movements. Experiment 2 reproduced this finding and showed that the timing of the onset and contact intervals did not evolve with the repetition of trial blocks. Therefore, the assumption of an internal clock that would trigger the successive movements must be rejected. The results are discussed in the framework of a modified two-stage model in which the internal clock, instead of triggering the tapping movements, provides target time points at which the movements have to produce their meaningful effects, that is, contacts with the response key. The timing distortions are likely to reflect both peripheral and central components.     

Cognitive development: Pastoral implications

How people think influences how they feel, and this combination of thinking and feeling drives behavior. While ministers often have a good understanding of the emotional dimension of the people who seek their counsel, xthe importance of cognitive development has often been understated in their education and training. With this in mind, this article discusses seven developmental stages of cognitive development and how each stage affects daily behavior. This discussion is followed by four pastoral implications.     

Detachment and defeasibility in deontic logic

The purpose of the paper is to present a logical framework that allow to formalize a kind of prima facie duties, defeasible conditional duties, indefeasible conditional duties and actual (indefeasible) duties, as well as to show their logical interconnections.     

Too Close to Quit: The Role of Project Completion in Maintaining Commitment1

Conlon and Garland (1993) demonstrated that information about the degree of project completion, as compared with information about sunk costs, seemed to be the driving force behind continued investment in an R&D project. In the present paper, we replicate and extend this work. In studies with experienced bank managers, Chinese graduate students, and advanced-level MBA students, we find overwhelming support for the importance of project completion on investment intentions, with no indication of typical sunk cost effects. We argue that our results support a goal substitution explanation for many escalation phenomena where, as progress moves forward on a project, completion of the project itself takes increasing precedence over other goals (e. g., economic profit) that may have been more salient at the time the project was initiated.     

Burnout and Leisure

The purpose of this study is to determine whether leisure behavior, leisure satisfaction, leisure attitude, and self-determination are associated with decreased burnout. A systematic stratified random sample of 438 clergy (55% return rate) was used to collect the data. In path analysis, results indicate that leisure behavior and leisure satisfaction had an inverse effect on all 3 components of burnout, while leisure attitude had no effect. Self-determination predisposition contributed inversely to 2 components of burnout. Similarly, age and years in ministry had a direct, inverse relationship with the emotional exhaustion and depersonalization dimensions of burnout. Number of years employed with the present church was also negatively related to emotional exhaustion. All 3 variables (age, years in ministry, and years with the present church) were positively associated with leisure behavior. Theoretical and practical implications of these findings are discussed.     

ASSESSMENT AND TREATMENT OF DESTRUCTIVE BEHAVIOR MAINTAINED BY STEREOTYPIC OBJECT MANIPULATION

In the current investigation, 2 participants with mental retardation displayed property destruction and stereotypy, and both responses involved the same materials (e.g., breaking and tapping plastic objects). Three experiments were conducted (a) to indirectly assess the functions of these two responses, (b) to determine their relation to one another, and (c) to develop a treatment to reduce the more serious behavior, property destruction. In Experiment 1, previously destroyed materials were either present or absent, and their presence reduced property destruction but not stereotypy. In Experiment 2, matched toys (ones that produced sensory stimulation similar to stereotypy) were either present or absent, or were replaced by unmatched toys (for 1 participant). Matched toys produced large reductions and unmatched toys produced small reductions in property destruction and stereotypy. In Experiment 3, attempts to pick up undestroyed objects were either blocked or not blocked while matched toys were continuously available. Response blocking reduced property destruction (and attempts), prevented stereotypy, and increased manipulation of matched toys. These results suggest that the two aberrant responses formed a chain (e.g., breaking and then tapping the object), which was maintained by the sensory consequences (e.g., auditory stimulation) of the terminal response, and that previously destroyed material or matched toys made the initial response (property destruction) unnecessary.     

Traditional Ideologies,Nontraditional Lives

This study examined how blue-collar couples whoalternate work shifts and share the care of theirchildren reconcile their traditional gender ideologieswith their nontraditional lives. In-depth interviews were conducted with twenty-three alternatingshift couples in which the husband was a blue-collarworker. Ninety-six per cent of the participants wereWhite, and the remainder were Hispanic. The results suggested that despite their nontraditionalbehavior, these couples maintained traditional genderidentities by adherence to three central beliefs abouttheir families: 1) the father was still the breadwinner; 2) the mother only worked in the paid laborforce because of financial pressures; and 3) the motherwas still the central parent. The ways in which each ofthese myths is constructed, and the functions they serve of both maintaining traditionalgender identity, and of obscuring potential conflictsbetween husbands and wives over identity arediscussed.     

CYCLE OF BLAME OR JUST WORLD

The conviction rate for sexual assault is persistently low in the United States. We propose a cycle-of-blame framework to highlight the possibility that the same rape myths that limit convictions are in turn strengthened by not-guilty verdicts. Participants read a summary of a rape trial. In different conditions, they were told that the jury's verdict was guilty or not guilty. In a No-Verdict condition, participants merely read the summary. All 96 participants subsequently responded to questionnaires measuring rape-myth acceptance and victim empathy. Gender affected both the myth and empathy measures, with women accepting fewer myths than men and exhibiting more empathy for the victim. Gender and Condition interacted such that men showed greater acceptance of rape myths and less empathy after a not-guilty versus a guilty verdict. Women evidenced consistently high empathy across conditions and greater myth acceptance after a guilty verdict. Although the cycle-of-blame principle is consistent with the performance of men, women's data require a different interpretation, which we base on just-world theory.