Locating information in an instruction manual : the effects of tab type and heading placement

An instruction manual was evaluated to determine the effects of tab type, heading placement and practice on time to locate information, number of errors and perceived ease of use. Forty-eight computer programmers from UNISYS Corporation, ranging in age from 21 to 50, participated in the study. Subjects in each of three tab groups -extended tabs, bleeded tabs, or no tabs -- searched for headings that were centered, left-justified, partially in the margin or fully in the margin. Search time results indicated that subjects located information more quickly with extended tabs than with bleeded tabs or no tabs, particularly for the first manual that they used. They also perceived the chapters to be easier to find with extended tabs. Bleeded tabs were associated with the longest search times for the first manual. Within each manual, a practice effect was found such that search times were longest for the first of three trial blocks. Error results indicated that users missed headings less often with margin and partial-margin headings and perceived them to be easiest to find, easiest to distinguish from the text and most aesthetically pleasing. However, for the no-tab group, the partial-margin headings were perceived as easier to find and more aesthetically pleasing than the margin headings. These results are discussed and recommendations are made regarding the use of extended tabs, as well as margin and partial-margin headings.