Deviating to the right: using eyetracking to study the role of attention in navigation asymmetries.

The ability to navigate accurately through the environment and avoid obstacles is essential for effective interactions with the environment. It is therefore surprising that systematic rightward errors are observed when neurologically intact participants navigate through doorways-most likely due to the operation of biases in spatial attention. These rightward errors may arise due to the operation of an extinction-like process, whereby participants overattend to the left doorpost and collide with the right one. Alternatively, rightward biases might reflect a bisection bias, such that the extrapersonal nature of the aperture causes participants to misbisect the aperture slightly to the right of true center. Because eye movements and spatial attention are closely related, in this study we used eyetracking to test the extinction and bisection models in a remote wheelchair navigation task. University students (n = 16) made rightward errors when navigating the wheelchair through a doorway, and fixated more frequently toward the right side of the aperture throughout the trial. These results are inconsistent with an extinction-based theory of navigation asymmetry, which predicts a leftward bias in eye position due to participants overattending to the left side of the doorway. Instead, the observed rightward bias in eye movements strongly supports a bisection-based theory of navigation asymmetry, whereby participants mentally "mark" the midpoint of a doorway toward the right and then head toward that point, resulting in rightward deviations. The rightward nature of participants' navigation errors and eye positions is consistent with the existence of a rightward attentional bias for extrapersonal stimuli.