Abstract
What initiates a change in the direction of travel? In previous studies of goal-directed walking (Cinelli & Warren, VSS 2007), we found that an active head turn toward a peripheral light produced a small path deviation (∼6cm) in the direction of the head. However, a passive head perturbation did not have the same effect, indicating that walkers do not simply follow their heads - at least when walking to a visible goal. Alternatively, the deviation might have resulted from attentional capture by a transient when the light was illuminated.
In the current study, we test which of four factors are sufficient to elicit a change in the direction of travel: (1) a steering synergy in which the eyes and head initiate a turn and the trunk and feet follow; (2) a saccadic eye movement without a head turn; (3) attentional capture by an external transient; and whether (4) a visible goal overrides such effects.
We dissociate these hypotheses by manipulating the following variables during walking straight toward a goal, while eye and head movements are recorded: (a) active head turn to peripheral light or face the goal; (b) saccade to peripheral light or fixate the goal; (c) respond to external transient or verbal command; and (d) goal or no goal. The results allow us to determine whether head turns, saccades, external transients, or some combination are sufficient to initiate a change in the direction of walking, and whether the presence of a goal overrides their influence.
Supported by NIH EY10923, CIHR MFE161734.