In this study, we investigate the effect of individual and group differences on the efficiency and effectiveness of map-based decision making under varying map use contexts. Specifically, we examine potential interrelationships between spatial ability (individual difference) and gender (group difference) for a map-based road selection task under varying time pressure scenarios. We first report on the results of an experiment involving human map display and map interaction tool preferences, based on people’s background differences. This is followed by results from a second experiment where we assessed participants’ response accuracy and confidence for the same map use context and tasks. We indeed find significant relationships between user background, map type, and inference making tasks. We also replicate the known phenomenon of male over-confidence in spatial decision-making, specifically for a road selection task under severe time pressure. Our results also demonstrate that commonly used classification and aggregation methods to study participant backgrounds can influence the outcomes of empirical map use studies and their respective interpretations.