## 3 Material and Methods
### Stimuli Images, Area-of-Interest (AOI), and Eye-Tracking Activity  
Over 1500 images from various construction sites, fabrication shops, and web scrapes were collected to build a robust dataset of fatal four near-misses. These images were carefully screened to meet the study's requirements for fatal four near-miss recognition, resulting in a shortlist of 106 images with potential fatal four near-misses. AOIs within each image were manually predefined. Experienced safety managers and construction personnel vetted and rectified the assigned AOIs for potentially fatal four near-miss opportunities. A near-miss event is defined as an incident that has a high probability of causing an accident or property loss. Special care was taken to collect images showing four potentially fatal hazards near construction workers. The final dataset comprised 54 images, including 42 images with 48 well-balanced fatal four near-miss AOIs and 12 false positives with no near-misses. Figure 3 illustrates the hierarchical structure of the fatal four near-misses and the image dataset for each trial. AOIs for this research are categorized in one of the following fatal four areas:  
* Slip, Trip, and Fall (falls from the same level, falls from heights, falls from ladders, falls from an elevated scaffolding or other elevated platforms)
* Struck-By (struck-by heavy equipment, vehicles, flying debris, falling objects, machinery, PPE violation, standing under the suspended object, etc.) * Caught-in-Between (such as being trapped under collapsing structures, equipment, material, caught between two mobilized objects, one stationary and one mobilized object, trench or excavation collapse, pinch point for lower and higher extremities)
* Electrocution (involving improper wiring, overloaded circuits, ungrounded equipment, contact with live circuits without PPE, contact with the energized source, improper use of tools or cords, etc.). Researchers have examined the optimal size for areas of interest (AOIs) and recommended that AOIs be large enough to encompass all fixation points for the object of interest. They found that smaller AOI sizes are preferable in studies with overlapping fixation distributions, where objects are closely spaced. Conversely, larger AOIs are recommended when there is a greater distance between objects. They proposed an AOI margin of 0.5\({}^{\circ}\) of visual  
Figure 3: Fatal four near-misses’ stimuli AOI selection process. angle as optimal for fitting models with overlapping fixations. However, other studies on AOI sizes generally suggest a visual angle margin of 1-1.5\({}^{\circ}\) for all experiments [87]. In this study, we employed two-dimensional near-miss scenario images as stimuli for an eye-tracking experiment to accurately assess workers' recognition performance under stressor conditions. The experiments were conducted in a controlled environment. Experimenting on an actual site was limited due to challenges in data acquisition and the potential introduction of noise that could have compromised the results based on the trial study. Participants were tasked with completing an eye-tracking activity as part of an experiment to evaluate their near-miss recognition performance. They observed construction site scenes (stimuli) on a monitor positioned 45 cm away and within their line of sight. The objective was to identify the fatal four near-misses in each scene. Each image was displayed for exactly 15 s, followed by a blank screen for an unspecified period. Participants also answered questions regarding their identification of near-misses in each image. This information was used to correlate their fixation data with their awareness and accuracy in identifying near-misses. This eye-tracking evaluation has been utilized in previous studies that investigate two-dimensional near-miss recognition ability [88]. Different stimuli images were used for each trial to remove the AOI familiarization and redundancy.