## 5 Conclusions  
This study investigated the performance of icon color combinations in interfaces using time pressure as an environmental variable based on cognitive load theory. The cognitive load calibration experiment corroborated the results of a previous study, thereby confirming that the use of different time pressures can influence the cognitive load level of participants. Based on this observation, three different levels of cognitive load, i.e., high, medium, and low, were established to conduct an icon search experiment to explore the optimal choice of icon color combinations for varying levels of cognitive load. Our findings confirmed that the choice of background color alone did not affect users' cognitive performance across the three cognitive load environments. Nevertheless, the foreground color of white was superior to that of turquoise under medium cognitive load environments. Moreover, the experimental results demonstrated varying performance differences among different color combinations under different cognitive load environments, with the white-on-black color combination displaying outstanding performance under high cognitive load environments and the white-on-blue combination performing the poorest. In medium cognitive load environments, the white-on-red, white-on-black, and white-on-purple combinations showed excellent performance, whereas yellow-on-blue performed the poorest. In low cognitive load environments, white-on-black and white-on-purple had the best cognitive performance, with marginal differences between color combinations. In summary, different scenarios should be considered during the design of interfaces. Designers typically prioritize white-on-black as the primary color choice owing to its favorable cognitive performance across all three cognitive load environments, and this conclusion is also in line with most of the previous research findings. White-on-purple can be considered in medium and low cognitive load environments. In high cognitive load environments, the white-on-blue color combination is not recommended, given that this combination may limit user cognitive performance. For medium cognitive load environments, the yellow-on-red combination can be considered. The experimental results of this study offer valuable insights into interface design in different scenarios. Nonetheless, there were some limitations in this study; for example, the participants were all between 18 and 24 years old, and there may be cognitive differences across age groups, which may limit the generalizability of the findings. Then again, although different cognitive load conditions were set in the experiment, factors such as whether participants' attention allocation and fatigue level were controlled may have affected the results. Further studies can focus on elucidating attention resource allocation, as well as explore the influence of brightness and contrast properties inherent to different colors. **Author Contributions:** Conceptualization, Q.G. ; methodology, B.Q. and L.Y. ; software, L.Y. ; validation, Q.G. and B.Q. ; formal analysis, B.Q. and L.Y. ; investigation, L.Y. ; resources, L.Y. ; data curation, L.Y. ; writing--original draft preparation, L.Y. ; writing--review and editing, Q.G. and B.Q. ; visualization, L.Y. ; supervision, Q.G. ; project administration, Q.G. ; funding acquisition, Q.G. All authors have read and agreed to the published version of the manuscript. **Funding:** This research was funded by [National Natural Science Foundation of China] grant number [71871056], and The APC was funded by [71871056]. **Institutional Review Board Statement:** The Central Government of the People's Republic of China has issued a Circular on the Measures for Ethical Review, which covers the scope of ethical review that is not involved in our manuscript. And our behavioral experiments were conducted in the form of mouse clicks. Therefore, our study was not ethically involved based on National legal provisions and did not require ethical approval.