Previous research has examined the effect of display size on distance estimation in static images and demonstrated that display size affects participant's distance estimate task performance. Several other researches have also reported similar outcomes. Examination of the experimental setups of these early researchers suggests that other factors may also contribute to the effect. In this paper, we report our investigations that extend the earlier research by examining the contribution of other factor such as viewing distance and physiological cues. By fixing the viewing distance of the observer, our research indicates that viewing distance (and physiological cues) does influence distance estimation. The large magnitude of effect size for display size factor however suggested that display size still constitutes a major influence in distance estimation task Copyright 2006 ACM.