Two types of ball-effector interaction and their relative contribution to soccer kicking

The study attempts a closer examination of the ball-foot interaction at the instant of soccer kicking using high speed videotaping. This allows a detailed biomechanical analysis of the collision. A central question is whether the ball-foot interaction can be modeled as an elastic impact, or as a mixture of ‘impact-like’ and ‘throwing-like’ patterns. The findings prove that the theory of conservation of momentum alone is not adequate for modeling kicking: additional momentum and mechanical energy is supplied to the system during the collision phase because of the muscle work. This is due to the relatively long duration of collision (about 16 ms) and the large ball-foot displacement (about 26.0 cm). More than 50% of the ball's speed and at least 30% of its kinetic energy is imparted to the ball without any contribution of the potential energy of the ball deformation.     

The (Non) Religion of Mechanical Turk Workers

Social science researchers have increasingly come to utilize Amazon's Mechanical Turk (MTurk) to obtain adult, opt‐in samples for use with experiments. Based on the demographic characteristics of MTurk samples, studies have provided some support for the representativeness of MTurk. Others have warranted caution based on demographic characteristics and comparisons of reliability. Yet, what is missing is an examination of the most glaring demographic difference in MTurk—religion. We compare five MTurk samples with a student convenience sample and the 2012 General Social Survey, finding that MTurk samples have a consistent bias toward nonreligion. MTurk surveys significantly overrepresent seculars and underrepresent Catholics and evangelical Protestants. We then compare the religiosity of religious identifiers across samples as well as relationships between religiosity and partisanship, finding many similarities and a few important differences from the general population.     

A crowdsourced nickel‐and‐dime approach to analog OBM research: A behavioral economic framework for understanding workforce attrition

Incentives are a popular method to achieve desired employee performance; however, research on optimal incentive magnitude is lacking. Behavioral economic demand curves model persistence of responding in the face of increasing cost and may be suitable to examine the reinforcing value of incentives on work performance. The present use‐inspired basic study integrated an experiential human operant task within a crowdsourcing platform to evaluate the applicability of behavioral economics for quantifying changes in workforce attrition. Participants included 88 Amazon Mechanical Turk Workers who earned either a $0.05 or $0.10 incentive for completing a progressively increasing response requirement. Analyses revealed statistically significant differences in breakpoint between the two groups. Additionally, a novel translation of the Kaplan‐Meier survival‐curve analyses for use within a demand curve framework allowed for examination of elasticity of workforce attrition. Results indicate greater inelastic attrition in the $0.05 group. We discuss the benefits of a behavioral economic approach to modeling employee behavior, how the metrics obtained from the elasticity of workforce attrition analyses (e.g., P _max) may be used to set goals for employee behavior while balancing organizational costs, and how economy type may have influenced observed outcomes.     

Feasibility,acceptability, and validity of crowdsourcing for collecting longitudinal alcohol use data

Challenges to conducting longitudinal research include financial, time, and geographic constraints. An emerging sampling method positioned to address these concerns is crowdsourcing. This study evaluated the feasibility, acceptability, and validity of collecting intensive longitudinal alcohol use data with the crowdsourcing platform, Amazon.com 's Mechanical Turk (mTurk). Participants (N = 278) recruited from mTurk provided weekly recordings of daily alcohol and soda use over an 18‐week period. Construct and external validity was evaluated using generalized linear mixed models describing associations of between‐subject (e.g., alcohol use severity) and within‐subject (e.g., day of week) variables with prospectively collected alcohol and soda use. High response rates were observed across the 18‐week period demonstrating feasibility (64.1%‐86.8%). The design was acceptable with 94% of participants indicating they were satisfied with the procedures. Multilevel models supported construct and external validity by replicating expected associations, such as more frequent and heavier drinking by individuals with higher AUDIT scores and on weekends. These effects were specific to alcohol use and did not extend to soda consumption. These data support the feasibility, acceptability, and validity of using mTurk for intensive longitudinal data collection. Future studies may leverage this platform to generate large, geographically diverse samples for prospective behavioral analytic research.     

A mediation model linking attachment to God,self-compassion,and mental health

Attachment theory posits that insecure attachment is a risk factor for the development of anxiety and depression and ample evidence supports this idea. Research has also demonstrated links between attachment to God and mental health, but little is known about the emotion regulatory mechanism that underlies this relationship. The present study explored the explanatory role of self-compassion in the relation between attachment to God and anxiety, depression, and life satisfaction in a sample of 181 adults who completed an online survey. Elevated attachment anxiety and avoidance were associated with higher depression and anxiety, and lower life satisfaction. Self-compassion mediated these associations (in an inverse direction for anxiety and depression), suggesting that people who feel uncomfortable depending on God, or who fear God's rejection, have difficulty extending kindness to themselves. Possible interventions are discussed in the context of these results.     

Infant's perception of goal-directed actions performed by a mechanical device

The present work investigated whether by the end of the first year, infants interpret actions performed by a mechanical device as goal-directed and why they would do so. Using a modified version of the Woodward (1998) habituation paradigm, 9- and 12-month-old infants were tested in a condition in which they saw a mechanical claw performing an action (Study 1). When infants viewed the claw grasping and transporting objects to the back of a stage, 12-month-old but not 9-month-old infants interpreted the action as goal-directed. In Study 2, 9-month-olds received prior to habituation an information phase showing infants how a human held and operated the claw. This enrichment of infants’ knowledge enabled 9-month-old infants to interpret the action display as goal-directed. The role of the developing means-end understanding and tool-use for infants’ interpretation of actions performed by a mechanical device is discussed.     

Specificity and variability of trunk kinematics on a mechanical horse

As perturbation training is gaining popularity, it is important to better understand postural control during complex three-dimensional stimuli. One clinically relevant and commonly used three-dimensional stimulus is found in hippotherapy and simulated hippotherapy on a mechanical horse. We tested nine healthy participants on a horse simulator, measured head and trunk kinematics, and characterized data in time (root-mean-square and variability) and frequency (amplitude spectra, gains, and phases) domains. We addressed three fundamental questions: 1) What is the specificity of postural responses to the simulator? 2) Which plane of motion is associated with the most and least variability (repeatable movements across repeated stimuli and across participants)? 3) To what extent are postural responses influenced by different degrees of stability (addition of pelvis straps and trunk support)? We found head and trunk responses were highly specific to the three-dimensional simulator perturbation direction and frequency. Frontal plane responses had the least variability across repetitions and participants whereas transverse motion was most variable. Head motion was more variable than the trunk at low frequencies and exhibited a marked decrease in tilt in the sagittal plane. Finally, the inclusion of pelvis straps had minimal effect on kinematics at low frequencies but altered higher frequencies; whereas added trunk support reduced head and trunk responses to perturbations and altered timing characteristics in all three planes. In conclusion, the present study suggests that frontal plane motion was under a high level of control, and results support the idea that specific head and trunk postural responses can be elicited from a complex three-dimensional stimuli, such as those found in hippotherapy. Researchers and clinicians can use results from this study to help interpret variability, implement mechanical adjustments to stability, and assess responses in pathological populations.     

Modelling the history of early modern natural philosophy: the fate of the art-nature distinction in the Dutch universities

The ‘model approach’ facilitates a quantitative-oriented study of conceptual changes in large corpora. This paper implements the ‘model approach’ to investigate the erosion of the traditional art-nature distinction in early modern natural philosophy. I argue that a condition for this transformation has to be located in the late scholastic conception of final causation. I design a conceptual model to capture the art-nature distinction and formulate a working hypothesis about its early modern fate. I test my hypothesis on a selected corpus of 25 works published in the Dutch academic milieu between 1607 and 1748. I analyse the corpus through a procedure based on concordancing of keywords associated with the model. I argue that the results obtained constitute a successful pilot study for the implementation of the model approach on larger scale research.