Abstract
Naive physics is one's own implicit knowledge about a universal physical law. We measure the naive physics by introducing time-to-passage (TTP) paradigm. In the TTP task, observers were asked to estimate the time distance for a moving target to pass behind a pre-determined landmark. In Experiments 1 and 2, a circular target smoothly moved in a linear path and on the way, was gradually occluded by a static screen rectangle. Additionally, a luminance border parallel to the motion path was presented as a pictorial cue evoking a ground surface. Since the motion path was oblique (+45 or −45 deg) or horizontal, the target appeared as if it descended, ascended or translated on the ground. As a result, when the target always contacted the solid line, TTP was significantly shorter in the descending condition than in the ascending condition. On the other hand, when the target was slightly away from the border, no significant effect of the slope of the motion path on the TTP was obtained. Therefore, the effect depends on whether or not the target appeared to move on the ground. Next, in Experiment 3, a black line was drawn on a diameter of the target stimulus and expressed the spin of the target by the direction of its rotation. We employed three types of spin, forward, backward, and no spin. The results showed that only when the target attached on the ground the target with backward spin led larger TTP than that with forward spin and with no spin, and we concluded this effect was attributable to representational friction. Moreover, Experiment 4 suggested this friction effect was triggered not only by visual cues but also by auditory cues. Our findings revealed that TTP judgment can reflect motion impressions evoked by the naive physics, representational gravity and friction.
This study was supported by Japan Society for the Promotion of Science.