The effect of good continuation on the contact order judgment of causal events

When a ball on a pool table moves to hit another ball, people feel the causal impression between the two balls: The first ball causes the second ball's motion, which is known as the launching effect. Previous research has shown that the causal impression becomes stronger when the two balls have a similar direction of movement. Here, we tested whether this good continuation influenced perception of the contact time between the causal object and the effect object. A variant of Michotte's visual collision event was used as a stimulus, consisting of two competing cause objects and one effect object. In the display, the two cause objects on the left begin to move and contact the effect object in the center, causing it to move. In Experiments 1 to 4, the contact order of the cause objects and the motion direction of the effect object were systematically varied. The observers were asked to judge which of the cause objects had a more causal relationship and made contact first. The results showed that the observers were more likely to judge a cause object as having a more causal relationship with the effect object when there was good continuation, and they often erroneously judged the cause object as having first contacted the effect object; this effect was maintained with up to approximately 100 ms of delay after contact. These results suggest that good continuation is an important cue that postdictively determines perception of the contact time of a cause object in a short time window.