Evaluation of Trade-Offs in Augmented Reality Head-Mounted Displays for Construction Assembly: Task Performance and Cognitive and Physical Ergonomics

Augmented reality (AR) head-mounted displays (HMDs) offer the potential to enhance construction task performance by enabling hands-free, real-time access to critical project information. Despite this promise, their impact on cognitive and physical ergonomics of workers remains underexplored due to challenges in creating realistic testing environments. This study investigates the use of AR HMDs with different display modalities in wood frame wall construction with a nail gun, focusing on their effects on task performance, situational awareness (SA), mental workload (MW), and physical movement. Three display conditions are evaluated: (1) a stereoscopic optical see-through HMD displaying registered conformal cues, (2) a monocular HMD showing static nonregistered informational diagrams, and (3) traditional printed documents as a baseline. The experiment was conducted in a full-scale, construction-simulated laboratory to enhance ecological validity, and a within-subjects design and vector-based analysis were employed to address individual variation within a small sample (n = 6) of carefully selected participants. Results show that the nonregistered HMD provided the best balance between task performance and SA in large-scale tasks, while the registered conformal AR HMD reduced specific assembly errors in small-scale tasks but increased MW and constrained physical movement due to visual occlusion. Compared to the paper condition, both AR HMDs resulted in more ergonomic postures and less dispersed motion. These findings highlight the need for AR systems that balance informational clarity with cognitive and physical demands, particularly in dynamic, high-risk environments like construction.