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Sara M. Scharoun, David A. Gonzalez, Eric A. Roy and Pamela J. Bryden

contrast, second-order planning entails modifying behavior in anticipation of secondary task demands. For example, grasping an overturned object uncomfortably (thumb down posture) to facilitate end-state comfort (ESC; thumb up posture; Rosenbaum et al., 1990 , 2012 ). Although there is an extensive body

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Casey M. Breslin and Mark Fischman

We tested the end-state comfort effect (ESCE) under varying reach extents (Experiment 1) and a balancing task (Experiment 2). We hypothesized that as reach extent increased, or when participants had to perform a simultaneous balancing task, sensitivity to end-state comfort would decrease. Participants were divided by height (taller or shorter than 160 cm) to understand the impact of reach extent. In Experiment 1, 86 participants grasped an overturned glass from a shelf, turned the glass upright, placed it on a counter, and then filled the glass with water. Shelf heights were 95, 145, and 168 cm above the floor. In Experiment 2, 82 participants climbed a stepstool, which posed a modest balance challenge, before grasping an overturned glass from a shelf 213.4 cm high. They then turned the glass upright and filled it with water. Three trials were performed. In each experiment, for individuals taller than 160 cm, a Cochran’s Q test revealed a majority used an awkward thumb-down grip to initially grasp the glass in all conditions. However, for participants shorter than 160 cm, sensitivity to end-state comfort decreased. This interaction suggests that the ESCE is influenced by both participant height and tasks requiring extreme reaches. Results are interpreted in context of a constraint hierarchy within a model of posture-based motion planning.

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Kathrin Wunsch, Anne Henning, Gisa Aschersleben and Matthias Weigelt

The end-state comfort (ESC) effect signifies the tendency to avoid uncomfortable postures at the end of goal-directed movements and can be reliably observed during object manipulation in adults, but only little is known about its development in children. The aim of the present paper is to provide a review of research on the ESC effect in normally developing children and in children with various developmental disorders, and to identify the factors constraining anticipatory planning skills. Three databases (Medline, Scopus, and PubMed) and relevant journals were scrutinized and a step-wise analysis procedure was employed to identify the relevant studies. Thirteen studies assessed the ESC effect in children, ranging from 1.5–14 years of age. Nine out of these thirteen studies reported the ESC effect to be present in normally developing children, but the results are inconsistent with regard to children’s age and the kind of ESC task used. Some evidence even suggests that these planning skills are intact in children with developmental disorders. Inconsistencies between findings are discussed in the light of moderating factors like the number of action steps, precision requirements, familiarity with the task, the task procedure, motivation, sample size, and age, as well as the cognitive and motor development of the participants. Further research is needed to investigate the onset and the developmental course of ESC planning, as well as the interdependencies with other cognitive abilities and sensory-motor skills.

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Breanna E. Studenka and Kodey Myers

actions are performed (e.g., the timing of action initiation). The choice of different actions by individuals with ASD can reveal differences in perceived constraints that influence motor planning. For example, individuals with ASD exhibit end-state comfort (i.e., ending an action in a comfortable posture

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Swati M. Surkar, Rashelle M. Hoffman, Brenda Davies, Regina Harbourne and Max J. Kurz

time to plan sequential movements during object manipulation task ( Mutsaarts, Steenbergen, & Bekkering, 2005 ), lack of fluid movement during prehensile task ( Mutsaarts, Steenbergen, & Meulenbroek, 2004 ), uncomfortable grip selection, and loss of the end-state comfort effect ( Mutsaarts, Steenbergen

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Christoph Schütz, Matthias Weigelt, Dennis Odekerken, Timo Klein-Soetebier and Thomas Schack

Previous studies on sequential effects of human grasping behavior were restricted to binary grasp type selection. We asked whether two established motor control strategies, the end-state comfort effect and the hysteresis effect, would hold for sequential motor tasks with continuous solutions. To this end, participants were tested in a sequential (predictable) and a randomized (nonpredictable) perceptual-motor task, which offered a continuous range of posture solutions for each movement trial. Both the end-state comfort effect and the hysteresis effect were reproduced under predictable, continuous conditions, but only the end-state comfort effect was present under nonpredictable conditions. Experimental results further revealed a work range restriction effect, which was reproduced for the dominant and the nondominant hand.

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Loes Janssen, Céline Crajé, Matthias Weigelt and Bert Steenbergen

We examined anticipatory motor planning and the interaction among both hands in a discrete bimanual task. To this end, participants had to grasp and manipulate two cylindrical objects simultaneously under varying conditions in which (a) the grip selection requirements, i.e., orientation of the to-be-grasped objects, differed between the two hands and (b) the type of grip for one hand was preinstructed, while the grip for the other hand was free choice. Results showed that participants, when grasping for two bars with a free grip choice, prioritized planning for comfortable end postures over symmetry of movement execution. Furthermore, when participants were free to choose a grip for their left hand, but were instructed on how to grasp an object with their right hand, we found no interaction between the grip selections of both hands, suggesting that motor planning proceeds independently for both hands.