Single-destination navigation in a multiple-destination environment: a new "later-destination attractor" bias in route choice.

People choose different routes depending on the size of the environment. However, the size of the environment is often confounded by cognitive load. The current study investigated whether changes in route choice varied as a function of memory load while keeping the size of the environment constant. Also, a new situation was used: route choice to a single destination as a function of the location of follow-up destinations. Critically, there were two routes of equal length to the first destination. The results showed that route choice to the first destination was influenced by the locations of later destinations. This (new) "later-destination attractor" bias is the tendency to take a route to the first destination that begins in the direction of subsequent destinations even when the route to the first destination is logically independent of the locations of subsequent destinations. In Experiment 1, all destinations were visible, and the bias was seen for both second and third subsequent destinations. In Experiments 2 and 3, only the first destination was visible, and the locations of the subsequent destinations were indicated on a diagram and had to be remembered by participants. In Experiment 3, the diagrams were misaligned by 180 degrees. Route choice to the first destination was still influenced by later destinations, but only by the nearer, second destination, and the extent of the bias was reduced as memory load increased. Indications are that differences in route choice between small- and large-scale environments may be due more to cognitive load than to environmental size.