Figure 1.

Experimental setup and procedure. (a) Visually guided walking paradigm and schematic of vector foot-placement error. (b) White two-dimensional Gaussian blob targets for each uncertainty condition. Grey dashed circles show the approximate size of the Medium and High uncertainty targets. These circles are for illustrative purposes only and did not appear during testing. (c) Each trial started with subjects fixating a plus sign on the walkway (at a distance of 50 cm with respect to the start position). After one second, we displayed all three targets at random positions and removed the fixation symbol. This signalled to the subjects to start walking. Examples of the Medium uncertainty condition for the consistent environment and one configuration of the variable environment are shown. Person illustration by Amanda Bakkum in (a) used with permission.