THE INFLUENCE OF COGNITION AND AGE ON ACCOMMODATION, DETECTION RATE AND RESPONSE-TIMES WHEN USING A CAR HEAD-UP DISPLAY (HUD)

Car head-up displays (HUDs), which portray information in the form of a virtual image reflected off a combiner, allow the viewing of complex information, such as route guidance, without the need for the driver to look away from the road ahead. The cognitive demand required by the HUD task may distract drivers from the outside world scene and cause reaction times to slow. Cognitive capacity also decreases with age. Th e aim of the present study was to determine the effect of cognitive de mand and age on the use of a car MUD. Subjects (young, middle or older age drivers, each group n = 8) performed a MUD-assisted driving task. with three levels of cognitive demand, whilst accommodation was simul taneously measured using a dynamically recording infra-red optometer. Response times to, and the detection rate of, changes in both the HUD image and the outside world scene were analysed. Increasing the cognit ive demand associated with the HUD image increased over-accommodation (greatest in the young, 0.34 +/- 0.05 D, p < 0,001), Response times to and detection of changes in the HUD image and outside world scene wer e significantly worse with increased cognitive demand. Response times to and detection of changes in the HUD image acid outside world scene also increased with age. The implication of the results with respect t o car HUD design and safety are discussed. (C) 1998 The College of Opt ometrists. Published by Elsevier Science Ltd. All rights reserved.