Figure 1

Stimuli and viewing conditions. (a) The three components of optic flow (translational, radial and rotational) were defined from RDKs. We used two different viewing conditions: full-field (left column) and peripheral vision (with an artificial scotoma that covered the 20° of the central visual field°, right column). Note that the scotoma is circled in white for illustration only. (b) RDKs were projected on a convex screen at a viewing distance of 180 cm. Younger (n = 42) and older (n = 42) adult participants had to fixate on the central red cross and to report the perceived motion direction of the stimuli. We manipulated motion coherence and estimated thresholds corresponding to 80% of correct detections. For illustration, a translational trial is shown at 20% of coherence. Signal dots are shown in white and noise dots in gray for better visibility on the figure (all the dots were white during the experiment).