Abstract: An experimental study was carried out on observations of single light stimulus and of combinations of 2—3 light stimuli presented from different directions while the subjects were operating Link Trainer along a flight course. A central group which did not operate on the machine, also took part in the experiment. The results shpwed that, in both groups, the stimuli appearing in the front direction are most easily discovered, especially so are those from the left-front (or rather from the middle of the left-front) direction. There is not much difference between the reaction time in observing the stimuli from the left and from the right. The most difficult one is the stimulus appearing at the back direction, When the three regions, namely, upper, middle, and lower regions are compared, it is found that stimuli in the upper region are most difficult to discover. When the number of stimuli increases to two or three, the observation becomes incomplete. Moreover, the greater the distance between the stimuli, the more imperfect will be the observation.

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