Consistent Layout of Function Keys and Screen Labels Speeds User Responses

Abstract

Personal-computer applications-software often requires people to navigate and select options using their keyboard's function keys where context-dependent meanings for these keys are assigned by guides or menus labeled on the screen. The physical layout of function keys on standard PC-compatible keyboards differs from the most common layouts of screen labels. This study examined user performance consequences of this simple, spatial, inconsistency. In a simulated order entry task, 36 participants each completed 240 trials, 40 with each of six different combinations of two keyboards and three screen guides with different spatial arrangements of function keys and screen labeling. One keyboard used the standard 5×2 function key pad and one used a single horizontal row of function keys; the screen guides were either a horizontal row, a vertical list, or a grid consistent with the standard key pad. We collected measures of response time, errors, and user preferences. Analysis of errors showed no reliable results. Analysis of response times showed several significant effects. Responses were faster with the two combinations of key pad and screen-guide layouts that were spatially consistent than with the four inconsistent layouts. Response times were also faster with the keyboard with horizontal function keys than with the standard layout, and slower with the vertical screen guide than with either of the other two guides. Over 80% of the participants thought the task was easiest when the screen guide matched the function key layout.