Table 1.

Description of parameters

Parameter	Unit	Description
Time	Seconds	Time, measured from the beginning of the task until task completion
Path length	Millimetres	Total distance travelled by the tip of the right and left instrument during the task
Mean force NZ	Newton	Mean absolute force exerted by the instruments on the task platform during periods when force is not zero
Maximal force	Newton	The highest absolute force as exerted by the instruments on the task platform during the task
Maximal impulse	Newton seconds	The largest product of force and the duration that the force was exerted, before force returned to zero (the area under a force peak if force is presented in time)
Force volume	Cubic Newton (N3)	The volume of an ellipsoid fitted around the standard deviations of the force along three principal components. (High force volume indicates fast increasing and decreasing forces in different directions.)
SD Force	Newton	The standard deviation of the absolute force

NZ non-zero, SD standard deviation