Determinants of task difficulty in human route-following tasks

We evaluate the difficulty of route-following in built environments. Participants repeatedly followed a route with 18 or 12 intersections, each with three or two choices. One group saw distinctive visual cues near each intersection, while a second group did not. In both groups, route-following accuracy increased by a similar amount when the number of intersections or choices decreased. Reaction time varied reciprocally to accuracy only with visual cues. Realistic optic flow decreased accuracy only without visual cues. We conclude that the number of intersections and choices were equivalent determinants of task difficulty, and that optic flow interfered with anticipatory decision-making.