In an earlier experiment the conspicuity of disc targets erected along a route in a suburban district was assessed in two field trials. One of the trials required observers to drive a motor vehicle along the route and to report the objects that attracted their attention when they were unaware of the presence of the disc targets. In the other trial, the observers were directed to locate and report the disc targets together with all road traffic control devices. The frequency of reporting the disc targets was taken as a measure of their conspicuity. In the first trial the measure is termed attention conspicuity since the disc target has to attract attention in order to be noticed; in the second trial the measure is termed search conspicuity, since the observers were directed to search for the targets. In order to test whether the result of these field trials of conspicuity could be predicted by laboratory experiment, several laboratory trials replicating the field trials were conducted using movie film and tachistoscopically projected coloured slides. It is shown that the laboratory studies can predict the relative conspicuity of the different disc targets. The movie film experiment provided a good prediction of the field experiment results and the use of tachistoscopically projected slides taken from a distance of 100 m and projected for 250 ms also afforded a satisfactory prediction. The laboratory experiment involving tachistoscopic projection of slides for 1500 ms provided the least satisfactory prediction. (Author/publisher)
Abstract