## 4 Discussion
### Icon Search Task
#### 4.2.2 Color Combination  
(a) High Cognitive load  
At high cognitive load levels, significant differences were identified between response times across the different color combinations. Of note, the response time for white-on-black icons was the shortest (mean = 1446, SD = 291) and significantly outperformed the other five color combinations. It is worthwhile emphasizing that the response time for yellow-on-red icons (mean = 1497, SD = 352) was also significantly lower than the other two color combinations.  
Noteworthily, the white-on-blue color combination showed poorer response time levels, with significantly higher response times than the other six color combinations. Under high cognitive load environments, where participants have limited information processing capabilities, using clear and easily recognizable icons is pivotal. This finding is instructive for interface design in high cognitive load environments; for example, fighter pilots have a high cognitive load due to the large number of tasks they often undertake under unfavorable conditions [33], so white-on-black and yellow-on-red color combinations of icons are chosen for the design of fighter operator interfaces over white-on-blue icons. This recommendation also applies in other high cognitive load scenarios, such as medical surgeries [34] or medical devices.  
(b) Medium Cognitive load  
Significant differences were also noted between response times between the different color combinations under medium cognitive load conditions. The response time for white-on-red icons (mean = 1537, SD = 368) was significantly better than the other five color combinations. Meanwhile, the response times for white-on-black (mean = 1542, SD = 450) and white-on-purple icons (mean = 1543, SD = 414) were superior to the other four color combinations. The yellow-on-blue color combination (mean = 2071, SD = 859), on the other hand, performed the poorest at the medium cognitive load level, with significantly longer response times compared to the other six color combinations. Therefore, white-on-red, white-on-black, and white-on-purple color combinations are recommended for interfaces for medium cognitive load environments, such as driving [35]. In contrast, the yellow-on-blue color combination should be avoided.  
(c) Low Cognitive load  
At the low cognitive load level, the differences between different color combinations were smaller than at the high and medium cognitive load levels, which may be ascribed to the fact that participants had more attentional resources available for lower cognitive loads, allowing them to allocate resources more efficiently [36]. Even though some color combinations had lower performance, participants were able to respond and recognize them quickly. Notwithstanding, superior color combinations were identified in the low cognitive load condition, with the white-on-black (mean = 1523, SD = 435) and white-on-purple (mean = 1533, SD = 364) combinations having significantly lower response times than the other four different color combinations. Therefore, these color combinations are recommended for the design of interfaces for low cognitive load environments. Examples include interface design for videos, chat rooms, and interactive activities [37] when high school students are learning concepts in a Web-based environment.