Users of modern GUIs routinely engage in visual searches for control items such as buttons and icons. The current research is intended to deepen our understanding of how the spacing between icons affects search times. Two experiments based on previous icon sets (Fleetwood & Byrne, 2002) were conducted in which the spacing between icons was systematically manipulated, and for which there was a computational cognitive model that predicted performance. Although the model's prediction that larger spacing would lead to slower search times was supported, there was an unanticipated finding: users were substantially slower than in similar experiments that employed consistent smaller spacing. The results were better fit with a model that employed a fundamentally different, less efficient search strategy. Eye-tracking data from a third experiment confirmed the effect of spacing on users' visual search behavior, but the system could not provide adequate information to explain the change in search behavior.