Effects of Item Grouping on Selection Efficiency

The effects of grouping items into categories were assessed for three methods of selection: 1) selecting a toolbar item with a mouse (Toolbar method); 2) selecting a menu item with a mouse (Menu method); and 3) selecting a menu item with a keyboard shortcut (Keyboard method). Users performed one of the three methods across 270 trials and had their speeds assessed in blocks of 30 trials. For each method, half the us-ers selected items from a single menu or toolbar while the other half selected items from two menus or toolbars. Overall, the Keyboard method was the fastest, followed by the Toolbar method. When two menus or toolbars were used, users reported making category decisions regardless of the method used. With the Menu method, category decisions did not slow performance because they were offset by faster item selec-tion due to fewer items in each menu when two menus were used. With the Toolbar method, the effect of fewer items in each toolbar when two toolbars were used was less pronounced. With the Keyboard method, there was no effect of fewer items in each menu because users recalled the keyboard shortcuts without looking at the menu items. These findings, coupled with past research that proficient use of the Keyboard method requires more trials than the other methods, confirm the use of toolbars for infrequently-used inter-faces and keyboard shortcuts for frequently-used interfaces