The purpose of this work was to examine performance in detecting traffic signs when subjects had drunk alcohol as compared to when they had not. Five drivers (undergraduate students) performed a detection task with and without ingesting alcohol. The amount of alcohol was close to the legal blood alcohol limit in Spain (up to 0.8 gr/l for non professional drivers). Forty-eight computerized stimuli were presented on a colour screen; half of them were pictures of traffic signs and the other half were signs showing irrelevant objects. A point was centred on the screen and preceding each picture, which was displayed peripherally somewhere around the central point. Subjects were instructed to locate the stimulus and to say `yes' or `no' depending on whether the given stimulus was a traffic sign or not. A record of eye movements using an NAC-EMR 600 allowed for obtaining measures of the time required to locate the stimulus (eye movement velocity from the previous fixation point at the centre of the screen), as well as measures of the duration of eye fixation on the target. Data analysis compared movement velocity and duration of fixation separately for traffic and non-traffic signs in each group of subjects. The results showed that performance is slightly deteriorated after consuming alcohol. Interesting consequences concerning vision during driving were found from these data. If alcohol ingestion affects a very simple task like this, the implications regarding its influence on a highly complex task like driving must obviously be much more important. (A)
Abstract