Effects of visual display separation upon primary and secondary task performances

Dual task performances were investigated as a function of the location of a peripherally mounted miniature CRT (cathode ray tube) which presented secondary task information. The location of the miniature CRT was varied across three levels of elevation and four levels of azimuth. Primary task information was presented by means of a stationary, centrally located CRT. The primary task required continuous monitoring of the primary display, while the secondary task required continuous tracking of an object on the secondary display. The results indicated that: performance on both tasks declined as the displays´ separation along the azimuth increased; performance decrements were greater when upward eye shifts were required to view the secondary display than when the corresponding downward eye shifts were required; and subjects´ ratings of discomfort were similar to the general pattern of performance decrements. The implications of these findings for the design of secondary displays are discussed