Submovement Analysis

Submovement Analysis

This topic is ONLY for MovAlyzeR.

Submovement analysis parses each stroke in to 3 segments: the primary and secondary submovements, and the total stroke (= the sum of the primary and secondary submovement). When submovement analysis is used, the output data referrs to segments 1, 2, and 3, which correspond to the primary submovement (segment 1), the secondary submovement (segment 2), and the total movement (segment 3), respectively.

The primary submovement is considered from movement onset to the first negative-to-positive point (or second zero-crossing) of the acceleration profile after peak velocity. The secondary movement(s) are subsequent negative-to-positive points in the acceleration profile. The end of the primary and the beginning of the secondary submovement is designated by the 'x'.

o Example: A trial with consisting of an initial forward movement followed by a small reverse movement is intepreted as two strokes.

Trial processed with Submovement Analysis and without One Stroke Analysis:

In the above graph,

For Stroke 1 starting at 0.49 sec, note that,

Duration of the primary submovement = 0.37 s
Duration of the secondary submovement = 0.11 s
Total duration = 0.48 s

For Stroke 2 starting at 0.96 sec, note that,

Duration of the primary submovement = 0.51 s
Duration of the secondary submovement = 0.00 s
Total duration = 0.51 s

Trial processed with Submovement Analysis and with One Stroke Analysis:

When specifying the entire trial as one stroke, all strokes are combined into one stroke first and then submovement segmentation takes place as described previously.

Hence, the stroke features are as follows:

Duration of the primary submovement = 0.37 s
Duration of the secondary submovement = 0.62 s
Total duration = 0.99 s

o The feature extraction is done for the primary, secondary and total movement, individually. The following exceptions apply:

~ Jerk per submovement cannot be normalized.

~ StartT of the total stroke is replaced by the relative duration of primary submovement (ratio of duration of submovement/duration of total stroke).

~ Vertical position of the total stroke is replaced by the relative distance of primary submovement (ratio of distance of submovement/distance of total stroke).

~ Horizontal position of the total stroke is replaced by 1 if secondary submovement exists and 0.0001 otherwise (0 could mean missing data). This is summarized in the following table:

Total-Stroke Feature	Submovement Features	Description
Start time of stroke (Stroke 3)	Duration of submovement 1 / Duration of total stroke	Relative duration of the primary submovement
Start Vertical position (Stroke 3)	Vertical size of submovement 1 / Vertical size of total stroke	Relative size of the primary submovement
Start Horizontal Position (Stroke 3)	1 if secondary submovement exists and 0.0001 otherwise	Frequency of secondary submovements
Normalized Jerk (JAbsN)	Square root of the integrated jerk squared (square-root ( 1/2 * Integral (dt j2(t))) [cm/s**2]	Integrated jerk (but not normalized)

NOTE: The other parameters are calculated similarly for all the strokes of a trial irrespective of whether they are primary, submovement or total strokes.