achromatic vision

Excerpts from Knut Nordby's autobiography: VISION IN A COMPLETE ACHROMAT

At this time (school) it became very obvious to me that my vision was different from that of other children. They could see things that I could not see; such as recognizing each other at a distance, spotting ripe berries on bushes and trees , reading cars' licence plates at a distance, etc. They could also take part in activities and sports, especially ball-games, that I could not. Hitting a ball with a bat, or catching a ball thrown towards me, was next to impossible for me, except under the most optimal light-conditions, such as in twilight; When teams were set up, I was always the last one to be taken on. I always memorized the colours of my own clothes and of other things around me, and eventually I learned some of the "rules" for "correct' use of colours and the most probable colours of various things: As an example, I learned that glass that was very dark to me usually was a dark cobalt-blue, glass that looked a bit lighter was usually bottlegreen, and so on. In this way, I could fool some people into believing that I had colour-vision and stop them from pestering me.

I only see the world in shades that colour-normals describe as black, white and grey. My subjective spectral sensitivity is not unlike that of orthochrornatic black & white film'. I experience the colour called red as a very dark grey, nearly black, even in very bright light. On a grey-scale the blue and green colours I see as mid-greys, somewhat darker greys if they are saturated, somewhat lighter greys when unsaturated, like pastel colours. Yellow is usually a rather light grey to me, but is usually not confused with white. Brown usually appears as a dark grey and so does a very saturated orange.

Picking berries has always been a big problem for me. I usually have to grope around among the leaves with my fingers, feeling for the berries by their shape, except in the shade or in the evenings when light levels are low. Then I can usually see the berries; the red ones as small "black' spheres among the "grey" leaves. The only berries I can easily see in bright sun-light are the white 'snow-ball" berries of the Guelder-rose bush.

  1. The Achromatopsia web site