We performed a user study that measured the effectiveness of our new 3D selection technique, Scope, which dynamically adapts to the environment by altering its activation area and visual appearance with relation to cursor velocity. Users tested our new technique against existing techniques Raycast, Bendcast, and Hook across a variety of different 3D scenarios which featured three different levels of object density and three different levels of object velocity. Our two dependent variables were completion time and total attempts per scenario. Users also completed a postquestionnaire which yielded qualitative insights on their experience. Our study shows that Bendcast, Scope, and Hook all performed similarly across all scenarios, yet were all significantly faster and less error-prone than Raycast. Despite this similar performance, users strongly favored Scope over the other three techniques, and over the second most preferred technique nearly two to one.