Consciousness not only consists of sensations but also perception of the components of the external events besides the mental events such as thoughts and memories (Chapter 5). The memory of color exists in our minds and we can easily identify such colors, if we see them properly. However, colorblind individuals can fail to identify certain colors. A test for color blindness employs the ishiara chart, which consists of numbers written in different colors in a background of other colors. When I took a color blindness test and a color blindness test at the periphery, I was able to identify most of the numbers. However, I was not able to see some numbers clearly, even though there are no limitations of my eyes that I am aware of. In fact, there are some slides in which I was not able to identify any number at all, especially the grey slides.
Vision is highly dependent on the stimulation of photoreceptors present in the retina. These photoreceptors are cones, and three types are in existence, the red, the green, and the blue cones. When one views an object as blue, it is because it reflects the blue light but absorbs red and green (Chapter 4). Therefore, the reflected blue light stimulates the blue cones and the object is seen as blue. In color vision, the ratio of stimulation of the three types of cones is a cause of disagreement. A wavelength of red light stimulates only the red cones and so do the others. However, in color blindness, it could stimulate other cones hence giving false impression of the color perception (Zeki, 1993). The fact that I was able to perceive the different colors, especially red, green, and blue, shows that my color vision is normal.
Consciousness not only consists of sensations but also perception of the components of the external events besides the mental events such as thoughts and memories (Chapter 5). The memory of color exists in our minds and we can easily identify such colors, if we see them properly. However, colorblind individuals can fail to identify certain colors. A test for color blindness employs the ishiara chart, which consists of numbers written in different colors in a background of other colors. When I took a color blindness test and a color blindness test at the periphery, I was able to identify most of the numbers. However, I was not able to see some numbers clearly, even though there are no limitations of my eyes that I am aware of. In fact, there are some slides in which I was not able to identify any number at all, especially the grey slides.
Vision is highly dependent on the stimulation of photoreceptors present in the retina. These photoreceptors are cones, and three types are in existence, the red, the green, and the blue cones. When one views an object as blue, it is because it reflects the blue light but absorbs red and green (Chapter 4). Therefore, the reflected blue light stimulates the blue cones and the object is seen as blue. In color vision, the ratio of stimulation of the three types of cones is a cause of disagreement. A wavelength of red light stimulates only the red cones and so do the others. However, in color blindness, it could stimulate other cones hence giving false impression of the color perception (Zeki, 1993). The fact that I was able to perceive the different colors, especially red, green, and blue, shows that my color vision is normal.
- Chapter 4. Sensation and Perception
- Chapter 5. State of Consciousness
- Zeki, S. (1993). A Vision of the Brain. Blackwell scientific publications.