Colour Blindness and Semantic Knowledge of Colour Terms
Colour blindness, or more specifically, colour vision deficiency (CVD), is a widespread visual condition affecting a significant proportion of the population, largely due to its X-linked recessive nature. Approximately 8% of men and 0.4% of women worldwide experience some form of this deficiency (Birch, J., 2012). This article explores the effects of CVD on semantic knowledge relating to colour terms, as examined in the recent study by Moreira et al. (2024). The Science Behind Colour Vision Deficiency CVD arises from the malfunctioning or absence of one of the three types of cones in the retina, which are responsible for colour perception. There are various degrees of severity: anomalous trichromacy, dichromacy and monochromacy. Dichromacy, for example, occurs due to the absence of one photopigment cone, leading to conditions such as protanopia and deuteranopia (Neitz & Neitz, 2011). This mainly affects the perc…
Colour blindness, or more specifically, colour vision deficiency (CVD), is a widespread visual condition affecting a significant proportion of the population, largely due to its X-linked recessive nature. Approximately 8% of men and 0.4% of women worldwide experience some form of this deficiency (Birch, J., 2012). This article explores the effects of CVD on semantic knowledge relating to colour terms, as examined in the recent study by Moreira et al. (2024).
The Science Behind Colour Vision Deficiency
CVD arises from the malfunctioning or absence of one of the three types of cones in the retina, which are responsible for colour perception. There are various degrees of severity: anomalous trichromacy, dichromacy and monochromacy. Dichromacy, for example, occurs due to the absence of one photopigment cone, leading to conditions such as protanopia and deuteranopia (Neitz & Neitz, 2011). This mainly affects the perception of colours in the red-green spectrum, drastically reducing the number of discernible colours for dichromats compared to normal trichromats (Linhares et al., 2008a, 2008b).
Research into Semantic Knowledge
The study conducted by Moreira et al. is groundbreaking in its exploration of how dichromats and trichromats perceive and cognitively process colour terms. Using the elicited-list method introduced by Berlin and Kay (1969), the researchers analysed lists of colour names generated by participants with normal colour vision and those with CVD. The aim was to understand whether there is a difference in the structural semantic knowledge of colour terms between these groups.
Methodology
The study involved 32 dichromats and 32 normal trichromats, with a rigorous screening procedure used to diagnose colour vision status by means of tests such as the Ishihara plates and the Rayleigh match on an anomaloscope (Birch, 2001). Participants were asked to write down, over a two-minute period with their eyes closed, all the colour terms they could recall, in order to exclude external visual influences—a novel approach that ensured only semantic memories were elicited.
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