*2.2.2 Acquisition*

When the optodes are aligned, signal acquisition is started. The test strategy was segmented into training and testing. The subjects were asked to complete six tasks that were identified by fNIRS.

A comfortable chair was set up roughly 100 cm away from the subjects so that the motion cues are visible to them while the screen backlight does not interfere with the optical sensors [25–38]. This environment was set up for signal extraction. The Easycap was prepared in advance to minimize the time consumption during the optode placement process. Yet some of the detectors/sources had to be optimized during the calibration process by fixing hair via gel. The session commenced with an undeveloped span of 30 seconds to create a reference point. Later the screen indicated the participants to perform one of six definite tasks the training was

#### **Figure 4.**

*Experimental model for signal acquisition.*

additionally divided into two parts. In the first part, all the tasks were recorded sequentially, i.e. the sequence of the tasks was pre-defined. In the second stage, the subjects were demanded to perform similar motions but with random intentions. All these six tasks were logged by fNIRS. Each task comprised of 10-second trials separated by a 20-second rest session. Particulars about the experimental model are given below in **Figure 4**.

The acquired data was then processed and is briefly illustrated in the coming section.
