TY  - JOUR
PY  - 1993//
TI  - Subsidiary task measures of driver mental workload: a long-term field study
JO  - Transportation research record
A1  - Zeitlin, Lawrence R.
SP  - 23
EP  - 27
VL  - 1403
IS  - 
N2  - Two auditory subsidiary task measures of driver mental workload, delayed digit recall and random digit generation, were evaluated in a 4-year field trial. Vanpool members performed the tasks for 2-min periods while traversing a mix of rural secondary roads, limited access expressways, high-density limited-access urban drives, and downtown city streets on a daily commute from upstate New York to New York City. The delayed digit recall task presented a sequence of random digits to the driver at 2-sec intervals for a 2-min period. The driver was required to recall the digit before the last one presented during the interdigit interval. Errors were scored for digits missed or omitted. The random digit generation task required the driver to verbalize a random sequence of digits from 1 to 9 for a 2-min period. The randomness of the generated sequence was determined by computer analysis. Data collected included the roadway being traversed, time of day, traffic conditions including density and estimated speed, weather, brake applications, and drivers' subjective difficulty ratings. Subsidiary task degradation was a conjoint function of traffic density, average speed, and uncertainty (estimated by the number of brake depressions). Weather conditions moderated these variables. Subjective difficulty ratings correlated with objective criteria of traffic density and speed. Unpredictability of traffic appeared to be the major determinant of perceived difficulty. The digit recall task correlated (r =.834) with a calculated driver workload index based on brake actuations divided by the square root of speed.       Record URL:         http://onlinepubs.trb.org/Onlinepubs/trr/1993/1403/1403-004.pdf<p /> <p>Language: en</p>
LA  - en
SN  - 0361-1981
UR  - http://dx.doi.org/
ID  - ref1
ER  -