Click, double click and blink would be distinguishable by
eyes-closing time which the sensor’s output is maintained over
2.5 V. It took 0.08-0.12 seconds for natural blink and at least
0.15 seconds for clicks (intentional blink). On the basis of
these data, we decided that an event will be identified as a click
when the time is above 0.14 s and the amplitude of the sensor
output is above 2.5 V. We decided that an event will be
identified as a double click when the time elapsed between the
first blink and the second blink is less than 0.2 s. The
mentioned time and amplitude were based on data collected for
the subjects who participated in this experiment. The decision
criteria can be adjusted according to the user.