Alexander M Gokan¹ (), Arthur G Shapiro¹; ¹American University

The remote control illusion (RCI) (Hedjar, Cowardin and Shapiro, 2018) is a method for measuring the spatial aspects of contrast perception. The luminance levels of two identical rectangular bars modulate at 2 Hz; when one bar is placed on a bright field and the other on a dark field, observers perceive the bars modulating in antiphase with each other (like contrast between the bars and their surround) and becomes light and dark at the same time (like the luminance of the bars). In RCI, bright rectangular flankers are added to both sides of the dark-field bar and dark flankers on both sides of the bright-field bar. An antiphase appearance occurs when flankers directly adjoin the bars or are separated by > 1°, but appear inphase when flankers are separated from the bars 20’. Here, we examine RCI with lights modulating along the L-M axis. In experiment 1, we compared the effect of luminance and equiluminance modulation. The configuration was similar to Hedjar et. al., and equiluminance was set using motion photometry. We varied the gap between bars and flankers and measured the proportion of antiphase trials each gap size. The luminance configuration replicates the original paper (that is, perception followed a “v” pattern: antiphase–inphase–antiphase as the gap between bar and flanker increased), but this pattern was not shown for the equiluminant configuration (typically, inphase-inphase-antiphase). In Experiment 2, we remeasured the patterns with modulation along color lines ranging from equiluminance to a 6% luminance and show that small shifts in color angles produce a transition between the equiluminance and luminance patterns. In Experiment 3, we show that inphase perception that arose when equiluminant flankers adjoin the bars, disappears when the width of the flankers increases, indicating that the LM contrast integrates over a larger area than luminance contrast.