Uncertainty in Human-Agent interactions is often studied in terms of transparency and understandability of agent actions. Less work, however, has focused on how Visual Environmental Uncertainty (VEU) that restricts or occludes visual information affects the Human-Agent Teaming (HAT) in terms of trust, reliance, performance, cognitive load and situational awareness. We conducted a mixed-design experiment (n=96) where participants interacted with an agent during a collaborative aiming task under four different types of VEUs involving global and dynamic occlusions. Our results show that while environmental uncertainties led to increases in perceived trust, they induced differences in reliance and performance. Counter to intuition, when participants trusted the agent the most, they relied on the agent more, but performed worst. These findings highlight how trust in agents is also influenced by external environmental conditions and suggest that reported trust in HAT scenarios may not always generalize beyond the environmental factors in which they were studied.
