Fig. 2

Vestibular and visual stimuli presented during the execution of the task in R/C conditions for all possible C durations (blue-dark red lines, in black the 1.400 s duration) in the blocks where C stimuli moved downwards (C direction Down); as depicted by the vertical arrows in block icons. VI (a-c), VE (d-f) and VV (g-i) sessions are hereby represented for their chair (a, d, g) and the visual target relative positions (b, e, h) in world reference. From the participant point of view, the visual stimuli visible through the VR-headset, resulting from visual (when present) and vestibular (when present) stimulations, are represented in panels c, f and I for VI, VE and VV sessions, respectively. In this representation the working area is 42 cm in front of the participant, as defined during the calibration phase (see text). In the sessions where the visual (VV) or vestibular (VI) stimulations were static, only a horizontal black line is depicted (as constant were the positions of the visual stimulus, panel h, or the chair, panel a, respectively). In VE no visual stimuli appeared on screen. Consequently, no positions are represented in e and f panels. In each panel from left to right, the three vertical dotted lines represent the beginning and the end of R and the beginning of C stimuli. C/R conditions were identical, changing only the order of presentation of C and R stimuli (not depicted). In C direction Up blocks, the C stimuli moved upwards, while the R stimuli moved downwards (not depicted).