DeLucia, Patricia R2022-10-112022-10-112021-082021-06-25August 202Weaver, Bradley William. "Effect of Motorcycle Lighting Configurations on Drivers’ Perceptions of Closing." (2021) Diss., Rice University. <a href="https://hdl.handle.net/1911/113692">https://hdl.handle.net/1911/113692</a>.https://hdl.handle.net/1911/113692Background: Motorcyclists account for a disproportionate number of roadway fatalities, especially at night. One major cause of this is drivers misjudging the approach of an oncoming motorcycle. The current research aimed to better understand how drivers perceive an approaching set of headlights and determined whether alternative motorcycle headlight configurations improved drivers’ perceptual judgments of closing for an oncoming motorcycle. Method: The first experiment examined whether drivers are more sensitive to horizontal or vertical optical expansion and whether drivers can integrate these two dimensions to achieve a lower looming threshold. A second experiment built on these results to inform the design of alternative motorcycle headlight configurations and tested whether these alternative headlight configurations were better than other motorcycle headlight configurations and a car’s headlights. For both experiments, participants were instructed to press a button to indicate when they first perceived an oncoming vehicle to be closing under nighttime driving conditions. Results: The first experiment showed drivers perceived closing at about the same looming threshold for horizontally-oriented and vertically-oriented motorcycle headlight configurations, and drivers perceived closing for a combined horizontal-vertical headlight configuration at a significantly lower looming threshold compared to the horizontal configuration but not compared to the vertical configuration. The second experiment showed the alternative motorcycle headlight configurations that accentuated the full extent of a motorcycle’s height or both its height and width resulted in drivers perceiving closing sooner than other motorcycle headlight configurations but not as soon as a car. Conclusion: Orientation does not affect driver’s looming threshold for closing, and drivers are not able to integrate optical expansion from multiple dimensions in a way that achieves a lower looming threshold. However, drivers do perceive closing sooner for larger headlight configurations compared to smaller headlight configurations unless the headlight configurations are relatively small.application/pdfengCopyright is held by the author, unless otherwise indicated. Permission to reuse, publish, or reproduce the work beyond the bounds of fair use or other exemptions to copyright law must be obtained from the copyright holder.motorcycle safetyvisual perceptiondrivingaccident analysisThesis2022-10-11