Just Noticeable Differences for Vehicle Rates of Closure

The goal for this research was to identify the just noticeable difference (JND) for vehicle rates of closure. In an attempt to identify the JND the author used two traditional psychophysical methods. However, these procedures resulted in aberrant relationships between rate of closure and percent correct. Both of the traditional procedures used a sequential presentation of a standard animation and a comparison animation. The final method used a change in the rate of closure within the animation. This method provided the author with a JND of between 12.9 to 16.1 km/h (8 to 10 mph). Reasons for the aberrant findings using the traditional methods are discussed.