Abstract
When searching for multiple objects, as e.g., in visual foraging, humans intend to interact with the objects, which also requires planning of the appropriate movement, such as reaching, grasping, or object handling. Despite this close link between visual foraging and action planning, their interaction has hardly been investigated in natural environments. To start closing this gap, we asked participants to pick and place LEGO bricks of one color in a non-exhaustive real-world foraging task. Specific instructions (collect, sort, pile) were used to set distinct precision requirements, and differences in task difficulty. We expected movement speed to vary with task difficulty and assumed that participants chose performance strategies to minimize efforts and energy-expenditure. For reach movement toward selected targets, we found higher average and maximum speed in the more difficult piling task compared to the two other tasks. Further, we found two main performance strategies used. First, participants preferred selecting targets closer to them and the placing area. Second, average reach distance toward selected targets increased with reach number (first, intermediate, or last reaches), both showing that participants tried to minimize movements systematically. However, reach distance was also influenced by task difficulty, with largest distances in the piling condition. We presume that larger distances were accepted to select targets particularly needed in the action sequence, e.g., large items early and small items late, to facilitate the overall piling process, and hence, task completion. The results highlight that in real-world studies, target selection heavily interacts with action planning. To conclude, action planning is central to visual search and target selection in natural environments. If task constraints allow, humans bias their target selection to areas and items which enable shorter reach movements and faster task completion.