Comparison of Horizontal and Vertical Menu Formats

Eight operators searched vertical and horizontal menus containing 4, 8, or 12 items in order to find a target item and report an associated numerical value. A within-subject design was used with menu orientation as a (balanced) blocking variable and number of items a random variable within blocks. The results indicate that operator search time is shorter for vertical than for horizontal menus. Number of items was also significant, but these factors did not interact. The orientation effect is large enough to be of likely practical significance in an operational environment.