Is your green my green? Probably not. What appears as pure green to me is likely to look a bit yellowish or bluish to you. This is because visual systems vary from person to person. Moreover, an ...

IF a circle, 2 cm. in diameter, is divided into quadrants and coloured as in Fig. 1, placed on either a black or white ground, and then viewed with one eye from a distance of about 3 m., it will be ...