THE GAP BETWEEN ROD AND FRAME INFLUENCES THE ROD-AND-FRAME EFFECT WITH SMALL AND LARGE INDUCING DISPLAYS

The role of the spatial separation between the ends of a rod and a fra me's inner edge (gap) in modulating the rod-and-frame effect (RFE) has been studied here with frames subtending either large or small retina l angles. With a large frame, rod settings were always in the directio n of frame tilt (direct effects) and varied inversely with gap size. W ith a small frame, rod settings were in the direction of frame tilt fo r tilts between 7.5-degrees and 15-degrees; with larger frame tilts, r od settings in the direction opposite that of the frame were observed (indirect effects). Increasing gap size produced a tendency toward neg ativity (away from frame tilt). Consequently, direct effects were larg er for small gaps, while the opposite was true for indirect effects. O verall, these results point to the importance of gap size in modulatin g the RFE, for both large and small displays.