The Cognitive Load Limits of Multiple Safety Signs

Current construction safety practices heavily rely on the use of multiple safety signs to mitigate potential risks. This study investigates the cognitive load imposed on construction workers by various design characteristics of safety signs, including text-only, pictogram with text, and pictogram-only signs. A comprehensive cognitive assessment of 513 construction workers was conducted to measure recall rates and visual attention. The results revealed that text-only signs led to lower cognitive load compared with pictogram-based signs, with no significant split-attention effect observed when text and pictograms were combined. The average recall rate across all sign types was 3.32 items, with over 95% of participants recalling six or fewer items. Additionally, recall rates for pictogram-based signs decreased significantly when more than nine items were displayed. Visual attention analysis indicated that while color had no significant impact, the order of placement did. These findings highlight the importance of limiting the number of safety signs and carefully designing them to optimize recall and reduce cognitive load. Future research should explore additional factors such as sex, complexity of work, and environmental conditions to develop a more comprehensive understanding of cognitive load in construction settings.