With a device called an Apprehension Meter, 60 undergraduate males watched a 5-min film of highway driving as seen from the driver's seat and recorded a moment-by-moment judgment of degree of danger, or caution level. From responses to six discrete hazards and to intervening uneventful periods, several summary scores were derived of which five differentiated significantly by driving record. The Safe Record group remained more cautious during the uneventful (baseline) periods, reacted to hazards sooner but more gradually, relaxed more gradually after their disappearance, and consequently remained alert to each hazard longer. The Violations group were at the other extreme, and the Accidents group intermediate. Hence the Safe group appeared more prompt in detecting danger, but less abrupt in responding to it, than did the groups with infractions. In terms of consistency across six hazards or 10 baselines, reliability (Cronbach's alpha) ranged from 0.48 to 0.99. A composite caution index had an alpha of 0.85 across hazards and correctly classified 77 per cent of subjects as either safe or non-safe. The results were found consistent with those in other studies.
Abstract