Exploring the Effects of Rotation on Time-to-Contact Estimates in a Prediction-Motion Task

The ability to extrapolate an occluded object’s position and arrival time is important for survival. These estimates, however, are not always accurate and can be affected by numerous contextual or object properties in a given situation. Rotational motion reflects changes in local motion signals that have been known to affect global motion processing. In this study, we examined the effects of rotational motion on time-to-contact (TTC) estimates for a horizontally translating object in a prediction-motion task. Each experiment included a visible occluder that varied across trials in both position and width. Thus, across experiments the duration of occlusion and the visible trajectory was analyzed for potential interactions with rotation and TTC estimates. Eye-movements were also analyzed for each experiment. Experiment 1 explored the effects of rotational direction (i.e., consistent versus inconsistent with the direction of global motion) vs. non-rotation for a circular object on TTC estimates. The results indicated that rotation, irrespective of its direction in relation to translation, resulted in an increase in overestimation of TTC. In Experiment 2, rotational speed was varied and examined as a potential object property for TTC estimation. There was not a significant effect for rotation speed on TTC estimates in the PM task. Lastly, Experiment 3 explored the relationship between translational speed and rotation, and its effects on TTC estimation. There was no significant effect of translation speed on TTC estimates. Rotation, however, had a similar and reliable effect on TTC estimates as the previous experiments. The results of the study found considerable evidence for a phenomenon that occurs for a rotating object in the prediction motion task. There was a significant effect of rotation on TTC estimates, irrespective of rotation speed and translation speed. Additionally, anticipatory eye movements to the point of contact, likely do not predict manual TTC responses. Future research could be directed towards understanding the role of eye movements in predicting TTC for a rotating object in the PM task