Prerecognition Sensory and Cognitive Processing of Traffic Signs

The authors reported that sign message (Stop, Left, Right, Slow) and sign format (word vs. symbol) influenced detection accuracy with exposures at which overall sign presence/absence detection was at chance level (24 msdc). Also, a duration judgment task showed that the brain had begun to extract sign message and format information with an exposure duration two standard deviations below that required for chance-level presence/absence detection (8 msec). The present research controlled a previously unsuspected luminance factor in testing (a) effects of sign message and format with 16, 8, 6, 4, and 2 msec exposures and (b) separable effects of sign shape, color and words. Sign message and format information was processed with exposures as brief as 4 msec and was apparently not mediated by prior separate processing of sign shape, color, or words.