Problem difficulty and waiting time shape the level of detail and temporal organization of visual strategies in human planning

TL;DR

This study investigates how problem difficulty and available time influence visual strategies and planning behavior in human problem solving, revealing that difficulty increases visual coverage and time shapes replanning and gaze-path coherence.

Contribution

It introduces the novel concept of misleadingness to measure problem difficulty and demonstrates how time constraints affect visual and planning strategies in complex tasks.

Findings

Harder problems reduce success rates and increase corrections.

More planning time improves plan coverage and gaze-path coherence.

Immediate action leads to online control compensating for incomplete planning.

Abstract

Planning entails identifying sequences of actions to reach a goal, yet we still have incomplete knowledge of how problem constraints, such as difficulty and available time, influence the visual strategies supporting plan construction, both in terms of coverage of the to-be-executed plans and its temporal organization. To fill this gap, we recorded participants' cursor and eye movements in a multi-target problem solving task on a grid. We manipulated two orthogonal dimensions: problem difficulty, by introducing the novel construct of misleadingness, which measures how nodes' distances on the grid diverged from their relative position along the solution, and waiting time, by allowing participants either to act immediately or wait before moving. We found that difficulty significantly affected both performance and gaze: harder problems reduced success rates, required more corrections and pauses, elicited longer pre-movement inspection that provided higher coverage of the to-be-executed plan, and more re-fixations. When participants could start immediately, they did so without fully consolidating their plan. This led to more pauses and backtracks, but also to more precise gaze-cursor alignment during execution, suggesting improved online control compensating for incomplete planning. With increased planning time, greater difficulty led participants to achieve a better temporal alignment between pre-movement visual inspection and cursor movement during execution. Overall, our results suggest that problem difficulty increases the visual coverage of the upcoming plan, whereas time availability shapes the extent of replanning during execution and determines whether gaze-path coherence emerges before movement or only during execution in difficult problems.