On speed overestimation effects in both mechanical and psychological causal events

Recent researches investigated a new illusory speed effect in visual events derived from the ones developed by Michotte to explore causal perception, in which there is spatiotemporal contiguity between two moving objects A and B (Vicovaro et al, 2020). We reported and discuss here from a theoretical perspective the results of three experiments exploring the relationship between the speed of A and the speed of B in different causal events. In one Experiment we presented the participants with stimuli that elicited a launching impression, and tested how the judged speed of B varied with variations of the pre-collision speed of A. In a second Experiment, we adopted stimuli in which object A could move with uniform positive or negative acceleration, to test whether the apparent speed of B depended on the speed of A at the moment of collision, as Newtonian laws of collision predict, or whether it depended on the overall motion pattern of A. Finally, we compared these results with similar findings (Parovel & Guidi, 2020) showing an overestimation of the motion of B in a psychological action-reaction sequence, where a moving object B is seen intentionally escaping from another object A, and we discuss this common effect according to the property transmission hypothesis. Moreover, this speed overestimation effect could be added to the list of functional effects of causality – both mechanical and psychological - on the low-level properties of the scene.