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A couple of days ago I was looking at the green tiles while lying in my new bathtub in Bend, Oregon. But they were not green anymore; they were what photographers of Ansel Adams’ zone-system ilk used to call Zone 5 grey. I have normal fully functioning color vision, which has been verified several times over the years. Also, I am quite conscious of color fatigue and what it does to my perceptions. Check out my posts on Experiments with your eyes and brain.

This bathtub color-fatigue experience was different because the color of the tiles was a fairly mild light green. One usually sees color-fatigue experiments done with strong pure colors because that brings on the exhaustion of the rhodopsin over the individual light-sensitive cones more quickly. In this case I was in the hot bath doing a therapeutic 105°F soak, because I had been moving furniture and books all day and was feeling – well, exhausted. The bath was to soothe my hyper-worked muscles.

The green perception was very slow to disappear and it took about half an hour of lying in the tub before I wasn’t seeing any green whatsoever and the tiles looked perfectly middle grey. This condition persisted until I left the light green bathroom and then my color vision seem to return to perfectly normal in a few seconds.

I was sufficiently surprised by this effect that a few days later, when back in my old digs in El Cerrito, California, to pick up more books and furniture, I took an identical bath in my old tub. This tub has tiles of approximately the same intensity but are a mild pink instead of mild green. I ran the temperature up to 105°F again to duplicate the experiment and lay there for the full half hour watching carefully for the color fatigue. Perhaps it was the heat that was causing the effect, but although my body temperature measured under the tongue rose to 102.0°F as it always does when taking these baths, there was no diminution of pink sensation in my eyes.

Okay, so this isn’t much of an earth-shaking discovery, but it is strange. Why does mild green get color fatigued and mild pink not get color fatigued? Is it just me — did I misread my own perceptions? Only conducting a few more tests will prove to me that I even had such an experience.