Hi Nalipuri, I might suggest an easier approach. Would it be unrealistic to use the keyboard eye gaze during record rather than making it a trigger item? I run my record at 75% or 50% and manage to get a good reaction time. If you choose not to do it this way, then record you eye gaze and then make it a contol trigger. I.e. Record your eye gaze in your time line, shorten it to your desired length, then creat a control trigger of the recorded sequence.
I always use the mouse to control the eyes (turn off camera mode, turn on mouse mode in the Face behavior ). I like looking at the screen when moving the eyes so I see what it looks like. I personally find the WebCam too hard to use for eyes as I have to look away to move the eyes, but then I cannot tell if its correct! (I have never used the keyboard for eyes - I did not even remember it was possible! Lol! So no suggestions on keyboard eyes from me.)