Two laboratory experiments evaluated symbolic versus verbal signs, and positive information (permissive) versus negative information (prohibitive) signs. Within each experiment two different forms of response to the signs were used. It was found that symbolic signs were better than verbal signs in perception time, and equal in accuracy of retention. There was no difference between positive and negative signs in retention, but negative symbolic signs were worse than positive and combination (positive plus negative) signs in terms of response time and errors. Combination signs were marginally superior overall, but the result was significantly affected by the subject's target direction and form of response. This paper was presented at session 38 "signing, delineation and guidance". The number of the covering abstract of the conference is IRRD no. 239340.
Samenvatting