. As a particular alphabet key (out of only five possible alphabet keys R, B, Y, W and G) was depressed on the machine panel (in response to a visual signal), the loaded software displayed a full VDU screen image (of a square shape) of the color whose first alphabet was pressed (i.e. if the subject depressed ‘R’, the software displayed a full VDU screen square ‘RED’ shaded image). This ultimately ensured correct task execution. When the task was incorrectly executed, the task was repeated in a random order. The software did not display an image if a key other than one of the five previously mentioned alphabets was depressed. Two more signals at the moment of ‘searched key pressing’ were recorded, the first on the x-axis of the oscilloscope and the second on the y-axis. On the x-axis, the time difference, in milliseconds, between the ‘finger-lift’ and the ‘searched key press’ moments was saved as the ‘motor action time’. When the searched key was depressed, the ‘applied force’ on the panel key was recorded in millivolts on the y-axis of the oscilloscope. Each subject executed the same task for five randomly-supplied visual stimuli (Red, Blue, Yellow, White and Green). The same experiment was conducted for all the participants. Finally, the average of five human per- formances, for the ‘search time’, the ‘motor action time’ and the ‘applied force’, was recorded for analysis. For experi- mental validation, a movie of each subject was also recorded by a video camera (Sony Digital Handycam; HDR-XR500:12 mega pixels). The video camera was used to record and photograph the subject to identify stress in full-body postures during CNC machine operation [44].