John J. van den Dobbelsteen

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One generally has the impression that one feels one's hand at the same location as one sees it. However, because our brain deals with possibly conflicting visual and proprioceptive information about hand position by combining it into an optimal estimate of the hand's location, mutual calibration is not necessary to achieve such a coherent percept. Does(More)
Reaching out for objects with an unseen arm involves using both visual and kinesthetic information. Neither visual nor kinesthetic information is perfect. Each is subject to both constant and variable errors. To evaluate how such errors influence performance in natural goal-directed movements, we asked subjects to align a real 5-cm cube, which they held in(More)
We investigated the extent to which humans can quickly adapt their goal-directed arm movements to perturbed feedback. We predicted that the magnitude of adaptation to a changed relationship between vision and kinesthesia would depend on the type of perturbation, being largest when the perturbation can be generalized within egocentric frames of reference. To(More)
Previous research has shown that humans generalize distortions of visuomotor feedback in terms of egocentric rotations. We examined whether these rotations are linked to the orientation of the eyes or of the shoulder of the arm that was used. Subjects moved a hand-held cube between target locations in a sequence of adaptation and test phases. During(More)
BACKGROUND To improve endoscopic surgical skills, an increasing number of surgical residents practice on box or virtual-reality (VR) trainers. Current training is mainly focused on hand-eye coordination. Training methods that focus on applying the right amount of force are not yet available. METHODS The aim of this project is to develop a system to(More)
BACKGROUND To improve endoscopic surgical skills, an increasing number of surgical residents practice on box or virtual reality (VR) trainers. Current training is focused mainly on hand-eye coordination. Training methods that focus on applying the right amount of force are not yet available. METHODS The aim of this project is to develop a low-cost(More)
BACKGROUND Residents in surgical specialties suture multiple wounds in their daily routine and are expected to be able to perform simple sutures without supervision of experienced surgeons. To learn basic suture skills such as needle insertion and knot tying, applying an appropriate magnitude of force in the desired direction is essential. To investigate if(More)
BACKGROUND It is generally assumed that safety of tissue manipulations during (laparoscopic) surgery is related to the magnitude of force that is exerted on the tissue. To provide trainees with performance feedback about tissue-handling skills, it is essential to define objective criteria for judging the safety of applied forces. To be of clinical(More)
BACKGROUND Surgeons may cause tissue damage by incorrect laparoscopic pinch force control. Unpredictable tissue and grasper properties may cause slips or ruptures. This study investigated how different forms of haptic feedback influence the surgeon's ability to generate a safe laparoscopic grasp while pulling tissues of variable stiffness using graspers(More)
BACKGROUND Currently, task time and errors are often used as performance parameters in laparoscopic training. Training with the focus on task time improvement alone results in fast, but possibly less controlled, instrument movements and therefore suboptimal tissue handling skills. METHODS Twenty-five medical students were randomly assigned in two groups.(More)