Measurement of minimum angle of resolution (MAR) for the spatial grating consisting of lines of two colors

Minimum angle of resolution (MAR) was measured for the grating which consisted of lines of two colors selected from Red, Green, Blue, White and Black. Method of two alternative forced choice (2AFC) was used where the participants were asked to answer the direction of the color grating of the horizontal or vertical directions. From the measured psychometric function of the ratio of the correct answers, MAR which corresponded to the threshold of 75% correct answer ratio was determined. MAR of the grating patches with more than one primary color was measured to be affected by the combination of colors and to be 10–30% larger than that of the grating patch of White–Black. While the resolving power for Blue pattern had been known to be worse than those for Green and Red patterns, MAR of the grating including Blue was not always the worst.