Van der Meij, H. (2002). Styling the index: Is it time for a change? Journal of Information Science, 28(3), 243-251.
Two empirical studies on the effects of indexing styles are presented. The research shows that there is an intricate relationship between task complexity and search efficiency afforded by style. A Run-In index yields the best performance when people engage in a search in which keyword and entry are identical. A Flush Right style, with leader dots to prevent line switching, yields the best performance for more complex search tasks as compared to a Run-In style or an Indented style. It is argued that a clear visual separation between entry and locator may help the user in keeping apart the distinct goals of searching for an entry and looking for a locator.