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The Radar for Europa Assessment and Sounding: Ocean to Near-surface (REASON) is a dual-frequency ice-penetrating radar (9 and 60 MHz) onboard the Europa Clipper mission. REASON is designed to probe Europa from exosphere to subsurface ocean, contributing the third dimension to observations of this enigmatic world. The hypotheses REASON will test are that (1) the ice shell of Europa hosts liquid water, (2) the ice shell overlies an ocean and is subject to tidal flexing, and (3) the exosphere, near-surface, ice shell, and ocean participate in material exchange essential to the habitability of this moon. REASON will investigate processes governing this material exchange by characterizing the distribution of putative non-ice material (e.g., brines, salts) in the subsurface, searching for an ice-ocean interface, characterizing the ice shell's global structure, and constraining the amplitude of Europa's radial tidal deformations. REASON will accomplish these science objectives using a combination of radar measurement techniques including altimetry, reflectometry, sounding, interferometry, plasma characterization, and ranging. Building on a rich heritage from Earth, the moon, and Mars, REASON will be the first ice-penetrating radar to explore the outer solar system. Because these radars are untested for the icy worlds in the outer solar system, a novel approach to measurement quality assessment was developed to represent uncertainties in key properties of Europa that affect REASON performance and ensure robustness across a range of plausible parameters suggested for the icy moon. REASON will shed light on a never-before-seen dimension of Europa and - in concert with other instruments on Europa Clipper - help to investigate whether Europa is a habitable world.

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There has been recent interest in the developmental trajectory of the end-state comfort effect (ESCE) in young children. However, potential sex differences have yet to be examined in the overturned glass task. We examined the ESCE using this task in a large sample (N=232) of typically-developing elementary school children (111 girls, 121 boys) in grades 1-5 (approximately 7-11years old). We sought to determine whether there were similarities or differences in performance between boys and girls. Children picked up an overturned drinking glass from a table, turned the glass upright, and then poured water into it from a measuring cup. Three trials were performed, and the use of an initial awkward thumb-down grip to pick up the glass was taken as evidence for the ESCE. There were non-significant main effects for sex and grade, but a significant interaction between factors. Boys increased in sensitivity to end-state comfort across the five grades while girls showed a decrease from grades 1-3, followed by an increase between grades 3 and 5. Taken together, the results indicate the presence of adult-like motor planning for the overturned glass task by the 4th grade (i.e., age 10), but also suggest the presence of a motor reorganization in girls, at around the 2nd or 3rd grade (i.e., 8 or 9years of age).

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Two experiments examined the dynamic interaction between cognitive resources in short-term memory and bimanual object manipulation by extending recent research by Logan and Fischman (2011). In Experiment 1, 16 participants completed a bimanual end-state comfort task and a memory task requiring serial recall of 12 words or pictures. The end-state comfort task involved moving two glasses between two shelves. Participants viewed the items, performed the end-state comfort task, and then serially recalled the items. Recall was evaluated by the presence or absence of primacy and recency effects. The end-state comfort effect (ESCE) was assessed by the percentage of initial hand positions that allowed the hands to end comfortably. The main findings indicated that the ESCE was disrupted; the primacy effect remained intact; and the recency effect disappeared regardless of the type of memory item recalled. In Experiment 2, 16 participants viewed six items, performed an end-state comfort task, viewed another six items, and then serially recalled all 12 items. Results were essentially the same as in Experiment 1. Findings suggest that executing a bimanual end-state comfort task, regardless of when it is completed during a memory task, diminishes the recency effect irrespective of the type of memory item.

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Two recent studies in this journal (Wulf, Chiviacowsky, & Cardozo, 2014; Wulf, Chiviacowsky, & Drews, 2015) assessed the additive effects of autonomy support and enhanced expectancies (Wulf et al., 2014) and autonomy support and external focus (Wulf et al., 2015) on learning a novel throwing skill. Participants learned to throw with their non-dominant arm at a target consisting of nine concentric circles with a center bull's eye. More points were awarded for throws landing closer to the bull's eye, but the precise landing location within each circle was ignored. All throws landing anywhere within a specific circle received the same score. I comment on the inappropriateness of this assessment for determining performance variability, which is an important characteristic of skill learning. The standard errors reported by Wulf et al. (2014, 2015) are confusing or ambiguous to performance as measured in the task. They do not reflect the precision of performance that one might expect. This problem is not limited to the two studies in this commentary, but remains a continuing one in many studies of motor learning. Questions are also raised concerning the absence of any kinematic or kinetic measures of throwing performance in Wulf et al. (2014, 2015).

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Knudson, Morrow, and Thomas ( 2014 ) recently summarized a number of important issues related to the quality of peer review and current peer-review practice in kinesiology. This writer endorses their six recommendations for improving peer review in kinesiology journals. The purpose of this commentary is to further highlight the importance of reviewer and associate editor recommendations to the editor, and the importance of editor decisions, in determining what becomes part of a discipline's body of knowledge. These recommendations and decisions ultimately affect what students learn, and what professionals practice, in their disciplines. This kind of power over the control of knowledge and the application of that knowledge is cause for all involved in science to do everything possible to improve our stewardship over peer review.

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Impulse-variability theory (R. A. Schmidt, H. N. Zelaznik, B. Hawkins, J. S. Frank, & J. T. Quinn, 1979) accounts for the curvilinear relationship between the magnitude and resulting variability of the muscular forces that influence the success of goal-directed limb movements. The historical roots of impulse-variability theory are reviewed in the 1st part of this article, including the relationship between movement speed and spatial error. The authors then address the relevance of impulse-variability theory for the control of ballistic, multijoint skills, such as throwing, striking, and kicking. These types of skills provide a stark contrast to the relatively simple, minimal degrees of freedom movements that characterized early research. However, the inherent demand for ballistic force generation is a strong parallel between these simple laboratory tasks and multijoint motor skills. Therefore, the authors conclude by recommending experimental procedures for evaluating the adequacy of impulse variability as a theoretical model within the context of ballistic, multijoint motor skill performance.

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In two experiments we examined the relationship between end-state comfort effects and memory performance in serial and free recall. In Experiment 1, 24 university students completed a bimanual end-state comfort task and a memory task. Participants viewed a series of 11 letters, then performed the bimanual overturned glass task in which they simultaneously moved two glasses from an upper shelf to a lower shelf, and then recalled the letters in either serial or free recall conditions. Memory recall was evaluated based on the presence or absence of primacy and recency effects. The end-state comfort effect was assessed by the percentage of initial hand positions that allowed the hands to end up in a comfortable thumbs-up posture. The end-state comfort effect was present in both memory conditions. The results revealed the disappearance of the recency effect in serial and free recall, although the effect was much stronger during serial recall. In Experiment 2, we asked whether simpler motor tasks might bring back the recency effect. Forty-eight participants completed either a bimanual or unimanual task that involved moving non-descript plastic cylinder(s) from an upper shelf to a lower shelf. An unexpected finding was that even after performance of the simpler motor tasks, the recency effect was still absent. The disappearance of the recency effect, regardless of the complexity of the motor task, suggests a reciprocal influence of physical action and cognitive processes, which we interpret as a basic concurrence cost.

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Franklin Henry's "memory drum" theory of neuromotor reaction (Henry & Rogers, 1960) was one of the most influential studies of the response programming stage of information processing. The paper is the most-cited study ever published in the Research Quarterly for Exercise and Sport. However, few people know there is a noteworthy error in the paper, namely in the description of the C movement, the most complicated of the three responses studied. Henry himself was unaware of the error for nearly 20 years after the paper's publication. The purpose of our paper is to accord the factual record its due respect by revealing the history about the error and its correction. The data are in the form of the original 1960 paper which describes the C movement, a paper by Howell (1953), and personal letters from Henry dating from 1979, when the error was first discovered, and continuing through 1986. In one letter, Henry attributed the error to a mild and specific form of aphasia, manifested by word reversals, from which he suffered throughout his scholarly life. Such a revelation makes the career of this remarkable scholar even more remarkable.

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The end-state comfort effect has been observed in recent studies of grip selection in adults. The present study investigated whether young children also exhibit sensitivity to end-state comfort. The task was to pick up an overturned cup from a table, turn the cup right side up, and pour water into it. Two age groups (N = 20 per group) were studied: preschool children (2-3 years old), and kindergarten students (5-6 years old). Each child performed three videotaped trials of the task. Only 11 of the 40 children exhibited the end-state comfort effect, and there were no differences between age groups. Results revealed the emergence of five different performance patterns, none of which were consistent with sensitivity to end-state comfort. The findings have implications for the advance planning of manual control in young children.

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During a unimanual grip selection task in which people pick up a lightweight dowel and place one end against targets at variable heights, the choice of hand grip (overhand vs. underhand) typically depends on the perception of how comfortable the arm will be at the end of the movement: an end-state comfort effect. The two experiments reported here extend this work to bimanual tasks. In each experiment, 26 right-handed participants used their left and right hands to simultaneously pick up two wooden dowels and place either the right or left end against a series of 14 targets ranging from 14 to 210 cm above the floor. These tasks were performed in systematic ascending and descending orders in Experiment 1 and in random order in Expiment 2. Results were generally consistent with predictions of end-state comfort in that, for the extreme highest and lowest targets, participants tended to select opposite grips with each hand. Taken together, our findings are consistent with the concept of constraint hierarchies within a posture-based motion-planning model.

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