p090fig03.03 Kanizsa square and reverse-contrast Kanizsa square precepts.  The spatial arrangement of pac-men, lines, and relative contrasts determines the perceived brightness of the squares, and even if they exhibit no brightness difference from their backgrounds, as in (b).  These factors also determine whether pac-men will appear to be amodally completed behind the squares, and how far behind them.<BR>||  p089c2h0.65 "... <BR>a) The percept of the square that abuts the pac-men is a visual illusion that is called the Kanizsa square. The enhanced brightness of the square is also an illusion.<BR>c) shows that these boundaries can be induced by either collinear edges or perpendicular line ends, and that both kinds of inducers cooperate to generate an even stronger boundary.<BR>d) if the perpendicular lines cross the positions of the illusory contours, then they can inhibit the strength of these contours. ..."