Spatial structure triggers systematic foraging: Segmenting search displays leads to searching by segments

Spatial structure often provides information about the likely location of targets in visual search tasks and in real life. However, the extent to which spatial structure affects attention when it provides no information about target locations is less well understood. This is investigated here using a visual foraging task, whereby individuals search for many targets amongst many distractors. In six online experiments, participants foraged for multiple instances of two target types amongst two distractor types, defined by either features or conjunctions. Experiments comprised a series of manipulations of the presence, quantity, visibility, and availability of spatial structure. This was achieved via visibly segmenting displays into areas containing equal numbers of objects. These experiments assessed the effects of spatial structure on foraging using a broad range of measures and across variations including the presence of time limits and visual feedback within the display. Task-irrelevant spatial structure consistently encouraged systematic foraging, whereby participants were more likely to continue foraging within one display segment rather than to move to another. Foraging in this manner was associated with costs to foraging efficiency, and benefits to spatial memory. The general strength of the visual information about spatial structure modified the extent to which this information affected systematic foraging and foraging efficiency. Overall, spatial structure can affect individuals' foraging patterns and strategies even when it provides no information about the potential locations of targets.