The Effect of Knee Joint Angle on Torque Control

The purpose of the author's investigation was to examine the effect of knee joint angle on torque control of the quadriceps muscle group. In all, 12 healthy adults produced maximal voluntary contractions and submaximal torque (15, 30, and 45% MVC [maximal voluntary contraction]) at leg flexion angles of 15°, 30°, 60°, and 90° below the horizontal plane. As expected, MVC values changed with respect to joint angle with maximum torque output being greatest at 60° and least at 15°. During the submaximal tasks, participants appropriately scaled their torque output to the required targets. Absolute variability (i.e., standard deviation) of torque output was greatest at 60° and 90° knee flexion. However, relative variability as indexed by coefficient of variation (CV) decreased as joint angle increased, with the greatest CV occurring at 15°. These results are congruent with the hypothesis that joint angle influences the control of torque.     

Variation of Isometric Response Force in the Rat

Hungry, unrestrained rats (N = 7) were rewarded for pressing a response beam in excess of 11 different force requirements. Changes in peak force production as a function of peak force requirement were examined by analyses of the first four moments of distributions of peak response forces: constant error, the within-subject standard deviation, skewness, and kurtosis. Results were similar to those previously obtained with human subjects: Constant error was positive at low and negative at high force requirements, the within-subject standard deviation increased as a negatively accelerating function of force requirement, and skewness and kurtosis were positive at low force requirements and decreased to negative values at the highest increments. Additional analyses of response kinetics indicated that rats, like humans, meet increasing force requirements by altering the rate of rise of force. The performance similarities suggest that common processes are engaged by the human and rat motor control systems to solve the problem of generating forces that are appropriate to the prevailing environmental constraints.     

The Relationship Between Balance Confidence and Cognitive Motor Interference in Individuals With Multiple Sclerosis

The authors examined and compared the development of oral and manual force control in preschool-aged children. In all, 50 typically developing children (aged 3-5 years) performed maximal strength tasks and submaximal visually guided tasks using tongue elevation, power, and precision grips. Dependent measures included strength, rate of force rise, initial force overshoot, force variability, and rate of force release. The authors performed age- and performance-related analyses. Results revealed similar changes for tongue, fingers, and hands across age- and performance-related measures for strength, initial force overshoot, and rate of force release. There were no significant changes in rate of force rise with increasing age. Force variability measures showed effector-specific changes with decreases across age- and performance-related measures for the hands and fingers but not for the tongue. Changes common across effector systems likely reflect biological development coupled with cognitive-strategic development. Effector-specific changes in force variability likely reflect experience gained through functional tasks influencing biological and cognitive-strategic development. Lack of change in force variability of the tongue suggests that fine control of the tongue is activity specific; thus, nonfunctional tasks are not likely to be sensitive to experience-related biological development.     

The Organization of Multisegmental Pulls Made by Standing Humans: II. Submaximal Pulls

Previously, an autonomous oscillator model with three parameters was derived that describes the relationship between anterior-posterior center of mass motions and pulling force for near-maximal, bimanual pulls made by standing subjects (Michaels, Lee, & Pai, 1993). The present study evaluated the extent to which a full range of pulling forces could be fit by the model and how the model's three parameters changed with intended pulling force. How much variation in force each parameter could contribute was determined by simulating the model. Qualitative and quantitative analyses of pulls made by 6 well-practiced subjects at 5%, 10%, 20%, 40%, 60%, 80%, and 95% of their maximum pulling force revealed that the model holds well, except for the least forceful pulls of some subjects. Two parameters appeared to be controlled; one, related to the position of the center of pressure, varied most among less forceful pulls; the second, related to the position of the center of mass at the time of handle-force onset, varied most among more forceful pulls. How these parameters might be set is discussed.     

Race/ethnicity and sex in U.S. occupations, 1970–2010: Implications for research,practice, and policy

We used census data on the civilian non-institutional adult population to analyze trends in labor force participation by race/ethnicity and sex in U.S. occupations from 1970 to 2010 in decennial periods. We examined these data for the main effects and interactions of race/ethnicity and sex across the total labor market and within 35 detailed occupations. Results from a log-linear analysis revealed that, as a whole (across race/ethnicity), more women participated in the labor force from 1970 to 2010. The proportions of working racial/ethnic minorities to both the population and the people in the labor force increased across all decades except for Black men. Although White (Caucasian) men continuously comprised the largest racial/ethnic–sex group working across five decades in absolute numbers, their percentage of the total working population declined from 1970 (54%) to 2010 (37%). In our analyses of 35 occupations, significant sex differences within racial/ethnic groups emerged. Overall, with some exceptions, Asian men and women and White women were more likely to be absorbed into occupations typically associated with professional status whereas Black, Hispanic, and American Indian men and women were more likely to be absorbed into occupations typically associated with low skill, low wages, and low status. Implications for the role of psychologists in future research, practice, and policy are discussed.     

Defensive Wars and the Reprisal Dilemma

I address a foundational problem with accounts of the morality of war that are derived from the Just War Tradition (JWT). Such accounts problematically focus on ‘the moment of crisis’: i.e. when a state is considering a resort to war. This is problematic because sometimes the state considering the resort to war is partly responsible for wrongly creating the conditions in which the resort to war becomes necessary. By ignoring this possibility, JWT effectively ignores, in its moral evaluation of wars, certain types of past wrongdoing. I argue that we can address this problem by incorporating an account of compensatory liability into an account of the morality of war. Doing so yields the view that, if we have culpably failed to compensate victims for past wrongs, we might be morally required to weigh the well-being of those victims more heavily in our calculation of proportionality when determining the permissibility of a defensive act that harms the victim as a side-effect. This, in turn, makes satisfying the proportionality constraint more difficult. The upshot is that sometimes, in order to wage a defensive war permissibly, we first have to discharge compensatory duties. This has implications for how we evaluate ‘cycles of reprisals’ that plague warfare.     

Precision Weapons,Civilian Casualties,and Support for the Use of Force

Precision weapons such as drones have become important elements of the military strategies of the United States and other countries. How does the use of precision weapons influence public support for the use of force? The public is averse to casualties, mission failure, and collateral damage. I argue that precision weapons increase the salience and importance of avoiding civilian harm. Individuals adopt their expectations about the outcomes of using these weapons and have lower tolerance for attacks that result in civilian deaths. This proposition is consistent with the results of two survey experiments. In the first, the possibility of civilian casualties leads to larger declines in support for the use of force than do military casualties or mission failure. In the second, respondents primed with information about an attack with precision weapons exhibited less tolerance for civilian harm than those primed with other weapons systems, despite the fact that the outcomes described to all respondents were identical.     

Methods and aims of investigative interviewing of adult witnesses: An analysis of professional practices

Eyewitnesses provide crucial evidence for the investigation of criminal cases. We analysed professional police interviewers’ behaviour by conducting a literature review. Our results indicate that the interviewing techniques used by untrained and trained investigators are predominantly inappropriate and harmful to memory recall. The way investigators curtail and select witnesses’ responses suggests that they look for specific information. As a subsequent step, we analysed investigative interviewing in terms of professional objectives, identifying the types of information that the police inquire about during the interview. Based on our results, we conclude future research should perform a fine-grained analysis of professional interviewing procedures with the aim of producing effective interviewing techniques that meet investigators’ real-world objectives.     

Perceived causality and perceived force: Same or different?

Visually perceived interactions between objects, such as animated versions of billiard ball collisions, give rise to causal impressions, impressions that one object produces some effect in another, and force impressions, impressions that one object exerts a certain amount of force on another. In four experiments, evidence for strong divergence between these two impressions is reported. Manipulations of relative direction of motion and point of contact between the objects had different effects on the causal and force impressions (Experiment 1); delay between one object contacting another and the latter starting to move had a stronger effect on the causal impression than on the force impression (Experiment 2); a context of other moving objects significantly weakened the causal impression but not the force impression (Experiment 3); and there was an inverse relation between an impression of one object penetrating another and the amount of force the former was perceived as exerting on the latter (Experiment 4). These findings are explained in terms of differential effects of instructions on attention, and also in terms of differences in meaning between force and causality.