Launching the effect: Representations of causal movements are influenced by what they lead to

We investigated whether the representation of an observed causal movement i s influenced by its observed effect. Subjects watched displays showing coll isions between two objects. In this "launching event'' (Michotte, 1946/1963 ), one of the two objects (Object A) started to move and set a second, init ially stationary, object (Object B) into motion, which gave a strong impres sion of apparent causality. The apparent effectiveness of A's movement was manipulated by varying the velocities of A and B. When the velocity of B wa s higher than that of A, the effectiveness of the collision was high; when it was smaller it was low. Then, subjects were asked to reproduce the veloc ity of the causal movement. Reproduced velocity followed the velocity of bo th Object A and Object B, which supports the hypothesis that the effect of a movement is integrated with its apparent cause. However, when apparent ca usality was reduced by changing the direction of motion of B or by covering the point of collision, the influence of the effect on the representation of the cause persisted, suggesting that retroactive interference may accoun t for the findings. The interference effect could not be reduced to tempora l recency or spatial integration and was not obtained in the reverse tempor al order (proactive interference). Rather, the two successive movements wer e blended in memory.