We’ve got to get moving: but when and for how long? by Ljubica Jovanovic


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Image credit : Morguefile

People walk, reach and point effortlessly, without having to consciously plan movements. However, if you ever tried to learn a dancing move, play an instrument or park a car, you would know to what extent our limbs can betray us. Problems can arise either in motor planning or while performing a movement, but our ability to estimate how well we performed is also important for acquiring skills. Previous research has suggested that how well people perform on spatial [1] and temporal [2] tasks can be explained by lack of insight in their own motor errors, suggesting new approaches to motor learning and rehabilitation.

 

Through a collaboration between the Laboratory for Perceptive Systems in Paris and the Vision and Control Action Group at the University of Barcelona within the PACE (Perception and Action in Complex Environments) initial training network, we investigated how different sources of noise (sensory and motor) contribute to performance when people are asked to synchronize their movement with a temporal demand. For example, when we want to catch a ball, our performance is affected by how well we can perceive its speed and direction, as well as how accurately we plan and perform the movement.

 

In order to investigate how people trade-off these different sources of noise in time, we asked participants to move their hand and point to a static target in front of them at a specific moment. Furthermore, we varied task difficulty by changing the size of the target or the time when participants are to reach to the target. Afterwards, participants were asked to estimate how successful they performed on each trial.

 

We found that people did adjust the speed and duration of their movement with respect to the task demands to some extent. However, their estimation of how well they performed did not follow their actual performance. Furthermore, results suggest that this lack of insight comes from poor estimation of movement duration and how variable it is. In other words, people do change the way they execute the movement to meet task demands, but do not have good estimation of how long or variable their movement is.

 

Synchronizing and timing our movements are challenging in many aspects and understanding the underlying mechanisms may help us designing efficient training or rehabilitation. According to our results, it would be important to investigate the potential role of performance assessment for skills acquisition. For example, different approaches to recovery after stroke take into account principles of motor learning [3] and the importance of feedback. However we do not know how important the estimation of performance may be for relearning a motor task, above and beyond the external feedback provided during rehabilitation. Using external feedback is efficient. Nevertheless, learning how to assess our performance may be beneficial for everyday conditions when it is not provided or waiting for it is too costly.

 

 

 References

[1] Zhang, H., Kulsa, M. K. C., & Maloney, L. T. (2015). Acquisition, representation, and transfer of models of visuo-motor error. Journal of vision15(8), 6-6.

[2] Mamassian, Pascal. “Overconfidence in an objective anticipatory motor task.” Psychological Science 19.6 (2008): 601-606.

[3] Krakauer, J. W. (2006). Motor learning: its relevance to stroke recovery and neurorehabilitation. Current opinion in neurology19(1), 84-90.

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