Abstract
When we perceive two objects that are moving toward a target and judge which object reached first, how accurate is the temporal order judgment? In order to investigate this, the present study examined a situation in which two objects move in the horizontal opposite direction each other. In the experiment, two small circles, whose positions were horizontally out of alignment, moved rightward and leftward from the ends of left and right in the monitor. These circles crossed around the target in the center position. Observers judged which circle reached to the target first in the conditions of some velocities and start positions of two circles. The results showed that observers tend to judge that the slow circle reached earlier than the fast circle though two circles reached simultaneously. However, the individual difference of judgments was great. Some observers tend to choose circles moving rightward as the first one and other observers tend to choose circles in the upper position. The reason why these results occurred was discussed.