Haptic human-human interaction does not improve individual visuomotor adaptation

Haptic interaction between two humans, for example, parents physically supporting their child while it learns to keep balance on a bicycle, likely facilitates motor skill acquisition. Haptic human-human interaction has been shown to enhance individual motor improvement in a tracking task with a visuomotor rotation perturbation. These results are remarkable given that haptically assisting or guiding an individual rarely improves their motor improvement when the assistance is removed. We, therefore, replicated a study that reported benefits of haptic interaction between humans on individual motor improvement for tracking a target in a visuomotor rotation. Also, we tested the effect of more interaction time and stronger haptic coupling between the partners on individual performance improvement in the same task. We found no benefits of haptic interaction on individual motor improvement compared to individuals who practised the task alone, independent of interaction time or interaction strength. We also found no effect of the interaction partner's skill level on individual motor improvement

Fast Data Sharing within a distributed multithreaded control framework for robot teams

In this paper a data sharing framework for multithreaded, distributed control programs is described that is realized in C++ by means of only a few, powerful classes and templates. Fast data exchange of entire data structures is supported using sockets as communication medium. Access methods are provided that preserve data consistency and synchronize the data exchange. The framework has been successfully used to build a distributed robot soccer control system running on as many computers as needed

Resistance is Not Futile: Haptic Damping Forces Mitigate Effects of Motor Noise during Reaching

Understanding how users adapt their motor behavior to damping forces can improve assistive haptic shared control strategies, for instance in heavy robot-assisted lifting applications. In previous experiments we showed that subjects reaching in constant and position-dependent longitudinal damping fields were able to reduce their movement time and increase end-point accuracy. The movement time versus movement distance and prescribed end-point accuracy agreed with Fitts' Law. However, why subjects were able to have shorter movement time while subjected to impeding damping forces is not explained by Fitts' Law. Based on the minimal variance principle we propose that humans exploit the noise-filtering behavior of constant or position-dependent damping forces. These damping forces attenuate mechanical effects of activation-dependent motor noise. This allows for higher motor activation and shorter movement time without losing end-point accuracy. Consequently, higher allowed motor activation allows for higher accelerations that lead to higher peak velocities, resulting in shorter movement times. Linear and non-linear stochastic optimal feedback control and optimal estimation models with multiplicative noise corroborate measurement data, supporting our hypothesis

Supplementary data for the study: “Haptic human-human interaction does not improve visuomotor adaptation.”

In this experimental study, we investigated the effect of haptic interaction between two humans on each partner's individual motor improvement of a tracking task in a visuomotor rotation. Collected data include motor performance and kinematic data

Haptic Human-Human Interaction Through a Compliant Connection Does Not Improve Motor Learning in a Force Field

Humans have a natural ability to haptically interact with other humans, for instance during physically assisting a child to learn how to ride a bicycle. A recent study has shown that haptic human-human interaction can improve individual motor performance and motor learning rate while learning to track a continuously moving target with a visuomotor rotation. In this work we investigated whether these benefits of haptic interaction on motor learning generalize to a task in which the interacting partners track a target while they learn novel dynamics, represented by a force field. Pairs performed the tracking task and were intermittently connected to each other through a virtual spring. Motor learning was assessed by comparing each partner’s individual performance during trials in which they were not connected to the performance of participants who learned the task alone. We found that haptic interaction through a compliant spring does not lead to improved individual motor performance or an increase in motor learning rate. Performance during interaction was significantly better than when the partners were not interacting, even when connected to a worse partner

Unmyelinated white matter loss in the preterm brain is associated with early increased levels of end-tidal carbon monoxide.

Increased levels of end-tidal carbon monoxide (ETCOc) in preterm infants during the first day of life are associated with oxidative stress, inflammatory processes and adverse neurodevelopmental outcome at 2 years of age. Therefore, we hypothesized that early ETCOc levels may also be associated with impaired growth of unmyelinated cerebral white matter.From a cohort of 156 extremely and very preterm infants in which ETCOc was determined within 24 h after birth, in 36 infants 3D-MRI was performed at term-equivalent age to assess cerebral tissue volumes of important brain regions.Linear regression analysis between cerebral ventricular volume, unmyelinated white matter/total brain volume-, and cortical grey matter/total brain volume-ratio and ETCOc showed a positive, negative and positive correlation, respectively. Multivariable analyses showed that solely ETCOc was positively related to cerebral ventricular volume and cortical grey matter/total brain volume ratio, and that solely ETCOc was inversely related to the unmyelinated white matter/total brain volume ratio, suggesting that increased levels of ETCOc, associated with oxidative stress and inflammation, were related with impaired growth of unmyelinated white matter.Increased values of ETCOc, measured within the first 24 hours of life may be indicative of oxidative stress and inflammation in the immediate perinatal period, resulting in impaired growth of the vulnerable unmyelinated white matter of the preterm brain