Effects of the orientation of moving objects on the perception of streaming/bouncing motion displays

In this study, we examined the contribution of the orientation of moving objects to perception of a streaming/bouncing motion display. In three experiments, participants reported which of the two types of motion, streaming or bouncing, they perceived. The following independent variables were used: orientation differences between Gabor micropatterns (Gabors) and their path of motion (all the experiments) and the presence/absence of a transient tone (Experiment 1), transient visual flash (Experiment 2), or concurrent secondary task (Experiment 3) at the coincidence of Gabors. The results showed that the events at coincidence generally biased responses toward the perception of bouncing. On the other hand, alignment of Gabors with their motion axes significantly reduced the frequency of bounce perception. The results also indicated that an object whose orientation was parallel to its motion path strengthened the spatiotemporal integration of local motion signals along a straight motion path, resulting in the perception of streaming. We suggest that the effect of collinearity between Gabors and their motion path is relatively free from the effect of attention distraction.