Figure 2.

Experimental protocol. Each trial consisted of three phases. First, subjects acquired the target either visually (V) or kinesthetically (K) with the head in an upright position. Next, in the absence of visual feedback about the target, but with vision of a structured visual surround, subjects tilted the head to the right or to the left. Conflict between the kinesthetically and visually perceived head tilt could be introduced at this stage (see Materials and Methods). Finally, subjects aligned the tool to the remembered target orientation under visual control only (V), under kinesthetic control only (K), or both (VK).