| Four simulated automobile driving experiments have been completed to investigate whether and how manipulation of optical looming of the retinal image of the lead vehicle (LV) might influence the following drivers' (FDs) braking behaviour. The goal is to advance our understanding of the role of looming cues in the control of locomotion, and in the meantime, explore a potential application of optical looming manipulation: a dynamic brake light for potentially reducing the rear-end collisions in automobile driving.; The highlights of the results are summarized as follows, according to Experiments I-IV respectively: (1) In comparison to braking behind a size-constant LV, FDs were found to brake sooner while encountering a size-increasing LV, whose size was manipulated during its braking in a manner that created a retinal expansion of the same LV image, of constant size, but at a rate of change that corresponded to an effective virtual displacement of distance (DeltaD), e.g. as if its actual position were closer to FDs by a certain constant distance, even though its actual position was unchanged. (2) FDs were found to advance or delay their braking behaviour, to an extent corresponding to the magnitude of manipulation, while following a LV whose optical image was manipulated according to an effective virtual displacement of time (Delta T), e.g. as if the LV were closer to, or further away from, the FV in terms of imposed time shift. (3) The same DeltaT manipulation was applied to the brake light triangle formed by two lower ones and the higher one at the rear of the LV, as an approximation of the dynamic brake light concept. Results showed that this concept was most effective for poor visibility conditions for which LV brake lights were most salient. (4) To further investigate the effect of looming cue manipulation, three looming cue manipulation methods were compared relative to No Manipulation (NM): Manipulation based on displacement of Distance (MD), displacement of Time (MT), and simple Size change (MS). Results show that MT is the most effective and feasible way to positively influence FD's braking behaviour. |
