Red-green colour blindness, an inherited X-linked anomaly, was analyzed both in its biological aspects (genetic frequency) and its pedagogical and psychological implications (only the latter are the exhaustive subject of this analysis). A mass screening was carried out by means of the Ishihara test between 1998 and 2000 in Calabria and Basilicata (South of Italy). A total of 63,933 male and female schoolchildren were investigated, belonging to 351 towns and 655 secondary schools (age range 11-14 years). Then, a psychological questionnaire was administered to the entire sample, while the psychological statistical analysis was made on the answers given by two sub-samples composed of 34,309 orthochromatic subjects of both sexes and 831 colour-blind subjects of both sexes. Their answers strengthen the hypothesis that dyschromatopsia could affect the human relations of its recipients starting from their childhood, forcing them to manage their diversity in order to adapt to rules, tools and didactic media and, generally, that dyschromates carry a common feeling which presupposes and takes for granted the univocality of the visual experience. Additionally, 3,082 teachers of different subjects have been submitted to a pedagogical questionnaire, consisting of 13 closed-open questions, in order to analyze the behavior of the school toward the colour-blind subject. (C) 2003 Wiley Periodicals, Inc.