Eye scanning of multi-element displays: I. Scanpath planning

We recorded oculomotor scanpaths in a task that required individuals to scan through displays consisting of a small number (between 3 and 12) of near-identical items. The task required each item to be fixated at least once and our objective was to explore the principles governing the generation of scanpaths. In general the observers carried out the task efficiently, although omissions occurred quite frequently (about 25% of trials) in the 12-item case. Backtracking occurred rarely except in the case of immediate rescanning back to the previously fixated item. Such immediate backtracking occurred on about 4% of fixations and, in contrast to more distant backtracking, was not associated with increased errors. Evidence was found for both directional (raster-like) scanning strategies and scanning strategies based on the global external contour.