Adaptation is the ability of our perceptual system to adjust to the surroundings. Our response to sustained stimulation decreases, indicating that our perceptual system is dynamic and depends on change to elicit a reaction. Therefore, the longer we are surrounded by the same stimulus, the less we notice, and it essentially becomes the new normal.
Our visual system is very adept at two particular types of adaptation: light and chromatic. Light adaptation allows us to adjust to changes in the level of illumination in our surroundings. For example, when viewed side by side, an illuminance difference by a factor of ten would look drastically different. However, if taken to a classroom with only electric lighting and then taken to a different classroom with electric lighting and daylighting, you would probably classify both spaces as having suitable lighting conditions, even though the illuminance in the daylit room could be more than ten times greater in certain areas than the other classroom. This is also a demonstration of Steven’s Power Law, with brightness being a stimulus with an “n” value less than one where the perceived increase is less than the actual increase. The other type of visual adaptation is chromatic adaptation, and this involves our perception of color. Every light source, including the sun, has a distinct spectral power distribution that defines the way colors appear when illuminated by that stimulus. Chromatic adaptation is the ability of our visual system to allow us to see objects and colors similarly under various light sources, and this is the concept behind my real-world example.
To prove the visual system’s ability to adapt, my lighting professor took my class to the lighting laboratory in the engineering units. The room is equipped with different spaces containing various light sources for experimentation. We entered the room and our professor had a discussion with us, telling us to look around at each other and our clothing. We then moved to one of the experimental areas that was dimly lit and shielded from the primary room by a black curtain, and we learned about the type of work that was being conducted there. Once finished, we returned the first room. Upon returning to the space, I looked around once again and noticed nothing out of the ordinary. I looked at my skin, at my clothes, and at the people around me. Only because we had been instructed to look around initially did I notice that the color red that one of my classmates was wearing looked slightly different than before.
Our professor broke the news to us that we were now sitting under completely different light sources than the ones we saw previously. The TA had switched to an alternative set of luminaires after we had left the space. While we had been observing the other space under dim lighting, our visual system had adapted to those lighting conditions. Therefore, upon returning to the primary space, we once again adapted to the new, brighter environment. At no point were we exposed to the different lighting conditions in the primary space in succession. The most interesting part of the experiment was when the lights that were originally illuminating the room were switched back on. The differences in color rendition were incredible. Everything was so much more vibrant under the original stimulus, and as the professor switched back and forth, my skin looked dull, almost sickly under the second stimulus. It was hard to believe that the conditions under the second stimulus had appeared normal to me. However, our eyes quickly adapted to the new lighting conditions, and using chromatic adaption, the colors and objects around us became familiar and appeared normal. However, in a side by side comparison, the two lighting environments were drastically different. It was a great example of adaptation to the surroundings by our perceptual system and how expectations play a role in defining our sensory experiences.
This was a very fun read dealing primarily with chromatic adaptation, or the color adaptation our eyes perform when stimulated with a variety of light sources. As I had written my blog on dark and light adaptation I found this to be an expansion of some of my preceding thoughts. Color adaptation, or chromatic adaptation, is much more interesting and utterly astounding when we consciously attempt to become more aware of it occurring in our environment. This individual wrote about an experience they had in a class under which they went through multiple changes in lighting conditions that greatly affected their perception of color. They went from their classroom in which they were instructed to take note of how people looked and the clothing they had. After which they moved to a dimly lit experimental room to have their eyes adapt to a different level of light stimulus. The next step was to go back into the original classroom and see how their eyes rapidly adapted back in the brighter stimulating environment. However they noticed things looked significantly more vivid and colorful upon them returning. However this was actually due to the TA changing out the previous illuminating lights with stronger ones. Interestingly now when they were exposed to the original lighting of the room everything appeared dull and almost as they explained “sickly,” showing how our visual system responds in swift and very intricate manners. This was an awesome example of chromatic adaptation that I myself would like to experience firsthand. The only similar experience I have had is from transitioning from a room illuminated with normal fluorescent lighting to a room with all black lights, which is certainly another good example of how we have a perceptual chromatic adaptation or change when experiencing changes in illumination.