Augmented reality (AR) is capturing increasing attention as a way to provide cognitive assistance in many fields. Inspiring from the benefits of AR, architecture, engineering, and construction industries and researchers are interested to apply AR technologies for various construction tasks such as design review, assembly, inspection, or facility maintenance, etc. However, even though AR technologies are designed to support users' cognitive capability by providing superimposed information on real-world scenes, this information from AR may lead to one's cognitive overload, causing an adverse effect on task performance. As a result, it is important to understand how AR would affect one's cognitive load, and in turn, task performance for better use of AR systems in construction. As a preliminary investigation, this research compared task performance and cognitive loads during traditional paper-based and AR-assisted rebar inspection tasks in the laboratory setting. Participants' task performance was measured by task completion time and the number of rebars correctly detected, whereas cognitive load was measured by the NASA task load index (TLX). Based on the result, we discussed the impact of AR application on rebar inspection tasks from a cognitive perspective.