Table 2.
The parameters of the visually guided reaching task
| Parameters | Description |
|---|---|
| Upper-limb postural control | |
| Posture Speed (m/s) | The mean hand speed for 500 ms before peripheral target illumination, when the hand should be at rest. |
| Visual reaction | |
| Reaction Time (s) | The time between illumination of the peripheral target and the onset of movement. |
| No Reaction Time | The number of trials for which movement to the destination target could not be detected. |
| Feed-forward control (initiation of movement) | |
| Initial Direction Error (radian) | The angular deviation between (a) a straight line from the hand position at movement onset to the destination target and (b) a vector from the hand position at movement onset to the hand position after the initial phase of movement. |
| Initial Distance Ratio | The ratio of (a) the distance the hand traveled during the participants’ initial phase of movement to (b) the distance the hand traveled between movement onset and offset. |
| Initial Speed Ratio | The ratio of (a) the maximum hand speed during the participant’s initial phase of movement to (b) the maximum hand speed during the trial. |
| Feed-back control (corrective responses) | |
| Speed Maxima Count | The number of maxima in hand speed velocity between movement onset and offset. |
| Min-Max Speed (m/s) | The differences between local speed peaks and minima. |
| Total movement metrics | |
| Movement Time (s) | The total time elapsed from movement onset to offset. |
| Path Length Ratio | The ratio of (a) the distance travelled by the hand between the movement onset and offset and (b) the straight-line distance between the starting and destination targets. |
| Max Speed (m/s) | The maximum hand speed during the trial. |
| No Movement End | The number of trials for which a stopping on the destination target was not detected. |
“Initial phase of movement” denotes the time from movement onset to the time of the first speed minimum
“Movement offset” indicates the time at which the participant finished their movement to the destination target; if the destination target was not reached, then movement offset is not calculated