Objective Achilles tendon protective shoes are medical orthoses that must be worn after Achilles tendon rupture surgery. Currently, these shoes predominantly feature black and gray color schemes and lack conspicuous warning markings, making them visually obscure and prone to accidental impacts, thereby increasing the risk of re-rupture. By conducting perceptual research on the application of warning colors and textures in the shoe upper, this study aims to explore design combinations that can effectively enhance visual warning, thereby improving the safety of the product during use and reducing the risk of secondary injury.

Methods Based on the theory of warning colors and combined with the visual warning arousal mechanism and eye-tracking physiological indicators, three typical biological warning textures (dots, cracks, stripes) and three warning color combinations (orange-black, yellow-black, purple-yellow) were selected to create nine experimental combinations. These were applied to a uniform model of Achilles tendon protective shoes as visual stimulus materials for the experiment. After collecting subjective valence ratings and eye-tracking data (including Time to First Fixation and pupil diameter), the data were analyzed using repeated-measures ANOVA, followed by post-hoc multiple comparisons using the LSD method. Pearson correlation analysis was conducted to examine the consistency between subjective and objective indicators, thereby comprehensively evaluating the perceived warning intensity of each combination.

Results The nine combinations of warning textures and colors showed no significant difference in Time to First Fixation, but exhibited significant differences in pupil diameter response and subjective warning valence ratings, with a significant interaction effect between texture and color. A moderate positive correlation was observed between subjective warning valence ratings and the increment of pupil diameter. Among these, subjects exhibited stronger alertness and a greater tendency to make avoidance decisions when viewing striped yellow-black and striped orange-black patterns. In contrast, alertness levels were significantly lower when observing striped purple-yellow or dotted pattern combinations. This indicates that while stripes are superior to dots in eliciting visual alertness, their actual effectiveness is significantly influenced by color interactions. The results of multiple comparisons revealed that the differences identified by subjective warning assessments were not fully captured by the objective physiological indicator of pupil diameter. The striped yellow-black pattern received significantly higher subjective ratings, influenced by cultural learning, symbolic semantics, and individual experience. In contrast, while the cracked-orange-black pattern elicited significant pupil dilation, it was not explicitly perceived as highly alerting. The striped orange-black pattern elicited a pupil diameter response ratio reaching the sympathetic activation threshold, accompanied by high alertness ratings, forming a complete alertness perception cycle that integrates both bottom-up and top-down processing. In contrast, the dotted yellow-black pattern produced a pupil diameter response ratio reaching the parasympathetic activation threshold, which can suppress sympathetic activity during the early stage of alertness stress. The findings suggest that the design of warning colors for Achilles tendon protective footwear should prioritize the selection of colors based on texture, rather than independently selecting texture or color.

Conclusion The stripe pattern in yellow-black serves as the optimal biological warning color paradigm for Achilles tendon protective shoes, significantly enhancing safety. The orange-black stripe pattern can be considered a secondary option, while the dot pattern in yellow-black should be avoided in warning signs.