Fig 1. Examples of potential trial displays are shown.
Saccade demand could be for a voluntary saccade only, a reflexive saccade only, a voluntary saccade followed by reflexive saccade or a reflexive saccade followed by a voluntary saccade. Instructions to participants were as follows: (A) if only an arrow appears make a response to the target it points at; (B) if only a new spot appears make a saccade to the spot; (C & D) if both an arrow and a new spot appear then execute two movements. In the VR block make a saccade to the spot indicated by the arrow first then a saccade to the new spot. In the RV block execute the movements in the other order: saccade to the new spot first then to the spot to which the arrow points.